1
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Pavani R, Tripathi V, Vrtis KB, Zong D, Chari R, Callen E, Pankajam AV, Zhen G, Matos-Rodrigues G, Yang J, Wu S, Reginato G, Wu W, Cejka P, Walter JC, Nussenzweig A. Structure and repair of replication-coupled DNA breaks. Science 2024; 385:eado3867. [PMID: 38900911 DOI: 10.1126/science.ado3867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 05/14/2024] [Accepted: 06/10/2024] [Indexed: 06/22/2024]
Abstract
Using CRISPR-Cas9 nicking enzymes, we examined the interaction between the replication machinery and single-strand breaks, one of the most common forms of endogenous DNA damage. We show that replication fork collapse at leading-strand nicks generates resected single-ended double-strand breaks (seDSBs) that are repaired by homologous recombination (HR). If these seDSBs are not promptly repaired, arrival of adjacent forks creates double-ended DSBs (deDSBs), which could drive genomic scarring in HR-deficient cancers. deDSBs can also be generated directly when the replication fork bypasses lagging-strand nicks. Unlike deDSBs produced independently of replication, end resection at nick-induced seDSBs and deDSBs is BRCA1-independent. Nevertheless, BRCA1 antagonizes 53BP1 suppression of RAD51 filament formation. These results highlight distinctive mechanisms that maintain replication fork stability.
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Affiliation(s)
- Raphael Pavani
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Veenu Tripathi
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Kyle B Vrtis
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Dali Zong
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Raj Chari
- Genome Modification Core, Frederick National Lab for Cancer Research, Frederick, MD, USA
| | - Elsa Callen
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Ajith V Pankajam
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | - Gang Zhen
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
| | | | - Jiajie Yang
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Shuheng Wu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Giordano Reginato
- Institute for Research in Biomedicine, Universita della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland
| | - Wei Wu
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, Shanghai, China
| | - Petr Cejka
- Institute for Research in Biomedicine, Universita della Svizzera italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland
| | - Johannes C Walter
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Harvard University, Boston, MA, USA
| | - André Nussenzweig
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, MD, USA
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2
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Otarbayev D, Myung K. Exploring factors influencing choice of DNA double-strand break repair pathways. DNA Repair (Amst) 2024; 140:103696. [PMID: 38820807 DOI: 10.1016/j.dnarep.2024.103696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 06/02/2024]
Abstract
DNA double-strand breaks (DSBs) represent one of the most severe threats to genomic integrity, demanding intricate repair mechanisms within eukaryotic cells. A diverse array of factors orchestrates the complex choreography of DSB signaling and repair, encompassing repair pathways, such as non-homologous end-joining, homologous recombination, and polymerase-θ-mediated end-joining. This review looks into the intricate decision-making processes guiding eukaryotic cells towards a particular repair pathway, particularly emphasizing the processing of two-ended DSBs. Furthermore, we elucidate the transformative role of Cas9, a site-specific endonuclease, in revolutionizing our comprehension of DNA DSB repair dynamics. Additionally, we explore the burgeoning potential of Cas9's remarkable ability to induce sequence-specific DSBs, offering a promising avenue for precise targeting of tumor cells. Through this comprehensive exploration, we unravel the intricate molecular mechanisms of cellular responses to DSBs, shedding light on both fundamental repair processes and cutting-edge therapeutic strategies.
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Affiliation(s)
- Daniyar Otarbayev
- Center for Genomic Integrity, Institute for Basic Science, Ulsan 44919, South Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science, Ulsan 44919, South Korea; Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, South Korea.
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3
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Budzko L, Hoffa-Sobiech K, Jackowiak P, Figlerowicz M. Engineered deaminases as a key component of DNA and RNA editing tools. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 34:102062. [PMID: 38028200 PMCID: PMC10661471 DOI: 10.1016/j.omtn.2023.102062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
Over recent years, zinc-dependent deaminases have attracted increasing interest as key components of nucleic acid editing tools that can generate point mutations at specific sites in either DNA or RNA by combining a targeting module (such as a catalytically impaired CRISPR-Cas component) and an effector module (most often a deaminase). Deaminase-based molecular tools are already being utilized in a wide spectrum of therapeutic and research applications; however, their medical and biotechnological potential seems to be much greater. Recent reports indicate that the further development of nucleic acid editing systems depends largely on our ability to engineer the substrate specificity and catalytic activity of the editors themselves. In this review, we summarize the current trends and achievements in deaminase engineering. The presented data indicate that the potential of these enzymes has not yet been fully revealed or understood. Several examples show that even relatively minor changes in the structure of deaminases can give them completely new and unique properties.
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Affiliation(s)
- Lucyna Budzko
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Karolina Hoffa-Sobiech
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Paulina Jackowiak
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
| | - Marek Figlerowicz
- Institute of Bioorganic Chemistry, Polish Academy of Sciences, Noskowskiego 12/14, 61-704 Poznan, Poland
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4
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Tabassum T, Pietrogrande G, Healy M, Wolvetang EJ. CRISPR-Cas9 Direct Fusions for Improved Genome Editing via Enhanced Homologous Recombination. Int J Mol Sci 2023; 24:14701. [PMID: 37834150 PMCID: PMC10572186 DOI: 10.3390/ijms241914701] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 09/27/2023] [Accepted: 09/27/2023] [Indexed: 10/15/2023] Open
Abstract
DNA repair in mammalian cells involves the coordinated action of a range of complex cellular repair machinery. Our understanding of these DNA repair processes has advanced to the extent that they can be leveraged to improve the efficacy and precision of Cas9-assisted genome editing tools. Here, we review how the fusion of CRISPR-Cas9 to functional domains of proteins that directly or indirectly impact the DNA repair process can enhance genome editing. Such studies have allowed the development of diverse technologies that promote efficient gene knock-in for safer genome engineering practices.
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Affiliation(s)
- Tahmina Tabassum
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia; (T.T.); (G.P.)
| | - Giovanni Pietrogrande
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia; (T.T.); (G.P.)
| | - Michael Healy
- Institute for Molecular Biosciences, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia;
| | - Ernst J. Wolvetang
- Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia; (T.T.); (G.P.)
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5
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Hamaker NK, Lee KH. High-efficiency and multilocus targeted integration in CHO cells using CRISPR-mediated donor nicking and DNA repair inhibitors. Biotechnol Bioeng 2023; 120:2419-2440. [PMID: 37039773 PMCID: PMC10524319 DOI: 10.1002/bit.28393] [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: 11/23/2022] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 04/12/2023]
Abstract
Efforts to leverage clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) for targeted genomic modifications in mammalian cells are limited by low efficiencies and heterogeneous outcomes. To aid method optimization, we developed an all-in-one reporter system, including a novel superfolder orange fluorescent protein (sfOrange), to simultaneously quantify gene disruption, site-specific integration (SSI), and random integration (RI). SSI strategies that utilize different donor plasmid formats and Cas9 nuclease variants were evaluated for targeting accuracy and efficiency in Chinese hamster ovary cells. Double-cut and double-nick donor formats significantly improved targeting accuracy by 2.3-8.3-fold and 19-22-fold, respectively, compared to standard circular donors. Notably, Cas9-mediated donor linearization was associated with increased RI events, whereas donor nicking minimized RI without sacrificing SSI efficiency and avoided low-fidelity outcomes. A screen of 10 molecules that modulate the major mammalian DNA repair pathways identified two inhibitors that further enhance targeting accuracy and efficiency to achieve SSI in 25% of transfected cells without selection. The optimized methods integrated transgene expression cassettes with 96% efficiency at a single locus and with 53%-55% efficiency at two loci simultaneously in selected clones. The CRISPR-based tools and methods developed here could inform the use of CRISPR/Cas9 in mammalian cell lines, accelerate mammalian cell line engineering, and support advanced recombinant protein production applications.
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Affiliation(s)
- Nathaniel K. Hamaker
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
| | - Kelvin H. Lee
- Department of Chemical and Biomolecular Engineering, University of Delaware, Newark, DE, 19716, USA
- The National Institute for Innovation in Manufacturing Biopharmaceuticals (NIIMBL), University of Delaware, Newark, DE, 19713, USA
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6
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Collias D, Vialetto E, Yu J, Co K, Almási ÉDH, Rüttiger AS, Achmedov T, Strowig T, Beisel CL. Systematically attenuating DNA targeting enables CRISPR-driven editing in bacteria. Nat Commun 2023; 14:680. [PMID: 36754958 PMCID: PMC9908933 DOI: 10.1038/s41467-023-36283-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Accepted: 01/25/2023] [Indexed: 02/10/2023] Open
Abstract
Bacterial genome editing commonly relies on chromosomal cleavage with Cas nucleases to counter-select against unedited cells. However, editing normally requires efficient recombination and high transformation efficiencies, which are unavailable in most strains. Here, we show that systematically attenuating DNA targeting activity enables RecA-mediated repair in different bacteria, allowing chromosomal cleavage to drive genome editing. Attenuation can be achieved by altering the format or expression strength of guide (g)RNAs; using nucleases with reduced cleavage activity; or engineering attenuated gRNAs (atgRNAs) with disruptive hairpins, perturbed nuclease-binding scaffolds, non-canonical PAMs, or guide mismatches. These modifications greatly increase cell counts and even improve the efficiency of different types of edits for Cas9 and Cas12a in Escherichia coli and Klebsiella oxytoca. We further apply atgRNAs to restore ampicillin sensitivity in Klebsiella pneumoniae, establishing a resistance marker for genetic studies. Attenuating DNA targeting thus offers a counterintuitive means to achieve CRISPR-driven editing across bacteria.
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Affiliation(s)
- Daphne Collias
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany.,Department of Chemical and Biomolecular Engineering, North Carolina State University, 27695, Raleigh, NC, USA
| | - Elena Vialetto
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany
| | - Jiaqi Yu
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany
| | - Khoa Co
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany
| | - Éva D H Almási
- Helmholtz Centre for Infection Research (HZI), 38124, Braunschweig, Germany
| | - Ann-Sophie Rüttiger
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany
| | - Tatjana Achmedov
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany
| | - Till Strowig
- Helmholtz Centre for Infection Research (HZI), 38124, Braunschweig, Germany.,German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Braunschweig, Germany
| | - Chase L Beisel
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080, Würzburg, Germany. .,Department of Chemical and Biomolecular Engineering, North Carolina State University, 27695, Raleigh, NC, USA. .,Medical Faculty, University of Würzburg, 97080, Würzburg, Germany.
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7
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Li J, Zhao H, McMahon A, Yan S. APE1 assembles biomolecular condensates to promote the ATR-Chk1 DNA damage response in nucleolus. Nucleic Acids Res 2022; 50:10503-10525. [PMID: 36200829 PMCID: PMC9561277 DOI: 10.1093/nar/gkac853] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 09/14/2022] [Accepted: 10/03/2022] [Indexed: 11/13/2022] Open
Abstract
Multifunctional protein APE1/APEX1/HAP1/Ref-1 (designated as APE1) plays important roles in nuclease-mediated DNA repair and redox regulation in transcription. However, it is unclear how APE1 regulates the DNA damage response (DDR) pathways. Here we show that siRNA-mediated APE1-knockdown or APE1 inhibitor treatment attenuates the ATR–Chk1 DDR under stress conditions in multiple immortalized cell lines. Congruently, APE1 overexpression (APE1-OE) activates the ATR DDR under unperturbed conditions, which is independent of APE1 nuclease and redox functions. Structural and functional analysis reveals a direct requirement of the extreme N-terminal motif within APE1 in the assembly of distinct biomolecular condensates in vitro and DNA/RNA-independent activation of the ATR DDR. Overexpressed APE1 co-localizes with nucleolar NPM1 and assembles biomolecular condensates in nucleoli in cancer but not non-malignant cells, which recruits ATR and activator molecules TopBP1 and ETAA1. APE1 protein can directly activate ATR to phosphorylate its substrate Chk1 in in vitro kinase assays. W119R mutant of APE1 is deficient in nucleolar condensation, and is incapable of activating nucleolar ATR DDR in cells and ATR kinase in vitro. APE1-OE-induced nucleolar ATR DDR activation leads to compromised ribosomal RNA transcription and reduced cell viability. Taken together, we propose distinct mechanisms by which APE1 regulates ATR DDR pathways.
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Affiliation(s)
- Jia Li
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Haichao Zhao
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Anne McMahon
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.,School of Data Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.,Center for Biomedical Engineering and Science, University of North Carolina at Charlotte, Charlotte, NC 28223, USA
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8
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Savitskaya VY, Monakhova MV, Iakushkina IV, Borovikova II, Kubareva EA. Neisseria gonorrhoeae: DNA Repair Systems and Their Role in Pathogenesis. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:965-982. [PMID: 36180987 DOI: 10.1134/s0006297922090097] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 07/12/2022] [Accepted: 07/12/2022] [Indexed: 06/16/2023]
Abstract
Neisseria gonorrhoeae (a Gram-negative diplococcus) is a human pathogen and causative agent of gonorrhea, a sexually transmitted infection. The bacterium uses various approaches for adapting to environmental conditions and multiplying efficiently in the human body, such as regulation of expression of gene expression of surface proteins and lipooligosaccharides (e.g., expression of various forms of pilin). The systems of DNA repair play an important role in the bacterium ability to survive in the host body. This review describes DNA repair systems of N. gonorrhoeae and their role in the pathogenicity of this bacterium. A special attention is paid to the mismatch repair system (MMR) and functioning of the MutS and MutL proteins, as well as to the role of these proteins in regulation of the pilin antigenic variation of the N. gonorrhoeae pathogen.
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Affiliation(s)
| | - Mayya V Monakhova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Iuliia V Iakushkina
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Irina I Borovikova
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Elena A Kubareva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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9
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Roy S, Juste SS, Sneider M, Auradkar A, Klanseck C, Li Z, Julio AHF, Lopez del Amo V, Bier E, Guichard A. Cas9/Nickase-induced allelic conversion by homologous chromosome-templated repair in Drosophila somatic cells. SCIENCE ADVANCES 2022; 8:eabo0721. [PMID: 35776792 PMCID: PMC10883370 DOI: 10.1126/sciadv.abo0721] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Repair of double-strand breaks (DSBs) in somatic cells is primarily accomplished by error-prone nonhomologous end joining and less frequently by precise homology-directed repair preferentially using the sister chromatid as a template. Here, a Drosophila system performs efficient somatic repair of both DSBs and single-strand breaks (SSBs) using intact sequences from the homologous chromosome in a process we refer to as homologous chromosome-templated repair (HTR). Unexpectedly, HTR-mediated allelic conversion at the white locus was more efficient (40 to 65%) in response to SSBs induced by Cas9-derived nickases D10A or H840A than to DSBs induced by fully active Cas9 (20 to 30%). Repair phenotypes elicited by Nickase versus Cas9 differ in both developmental timing (late versus early stages, respectively) and the production of undesired mutagenic events (rare versus frequent). Nickase-mediated HTR represents an efficient and unanticipated mechanism for allelic correction, with far-reaching potential applications in the field of gene editing.
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Affiliation(s)
- Sitara Roy
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Sara Sanz Juste
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Marketta Sneider
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Ankush Auradkar
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Carissa Klanseck
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Zhiqian Li
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Alison Henrique Ferreira Julio
- Instituto de Ciências Biomédicas (ICB), Universidade Federal do Rio de Janeiro, Av. Carlos Chagas Filho 373, Ilha do Fundão, Rio de Janeiro, 21941-902 RJ, Brazil
| | - Victor Lopez del Amo
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
| | - Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
- Tata Institute for Genetics and Society-UCSD, La Jolla, CA 92093-0335, USA
| | - Annabel Guichard
- Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0335, USA
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10
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Castellanos M, Verhey TB, Goldstein M, Chaconas G. The Putative Endonuclease Activity of MutL Is Required for the Segmental Gene Conversion Events That Drive Antigenic Variation of the Lyme Disease Spirochete. Front Microbiol 2022; 13:888494. [PMID: 35663861 PMCID: PMC9159922 DOI: 10.3389/fmicb.2022.888494] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 04/18/2022] [Indexed: 11/30/2022] Open
Abstract
The Lyme disease spirochete Borrelia burgdorferi, encodes an elaborate antigenic variation system that promotes the ongoing variation of a major surface lipoprotein, VlsE. Changes in VlsE are continual and always one step ahead of the host acquired immune system, which requires 1–2 weeks to generate specific antibodies. By the time this happens, new VlsE variants have arisen that escape immunosurveillance, providing an avenue for persistent infection. This antigenic variation system is driven by segmental gene conversion events that transfer information from a series of silent cassettes (vls2-16) to the expression locus, vlsE. The molecular details of this process remain elusive. Recombinational switching at vlsE is RecA-independent and the only required factor identified to date is the RuvAB branch migrase. In this work we have used next generation long-read sequencing to analyze the effect of several DNA replication/recombination/repair gene disruptions on the frequency of gene conversions at vlsE and report a requirement for the mismatch repair protein MutL. Site directed mutagenesis of mutL suggests that the putative MutL endonuclease activity is required for recombinational switching at vlsE. This is the first report of an unexpected essential role for MutL in a bacterial recombination system and expands the known function of this protein as well as our knowledge of the details of the novel recombinational switching mechanism for vlsE variation.
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Affiliation(s)
- Mildred Castellanos
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Theodore B. Verhey
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - Madeleine Goldstein
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
| | - George Chaconas
- Department of Biochemistry and Molecular Biology, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, Snyder Institute for Chronic Diseases, University of Calgary, Calgary, AB, Canada
- *Correspondence: George Chaconas,
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11
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dCas9-based gene editing for cleavage-free genomic knock-in of long sequences. Nat Cell Biol 2022; 24:268-278. [PMID: 35145221 PMCID: PMC8843813 DOI: 10.1038/s41556-021-00836-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Accepted: 12/21/2021] [Indexed: 12/14/2022]
Abstract
Gene editing is a powerful tool for genome and cell engineering. Exemplified by CRISPR–Cas, gene editing could cause DNA damage and trigger DNA repair processes that are often error-prone. Such unwanted mutations and safety concerns can be exacerbated when altering long sequences. Here we couple microbial single-strand annealing proteins (SSAPs) with catalytically inactive dCas9 for gene editing. This cleavage-free gene editor, dCas9–SSAP, promotes the knock-in of long sequences in mammalian cells. The dCas9–SSAP editor has low on-target errors and minimal off-target effects, showing higher accuracy than canonical Cas9 methods. It is effective for inserting kilobase-scale sequences, with an efficiency of up to approximately 20% and robust performance across donor designs and cell types, including human stem cells. We show that dCas9–SSAP is less sensitive to inhibition of DNA repair enzymes than Cas9 references. We further performed truncation and aptamer engineering to minimize its size to fit into a single adeno-associated-virus vector for future application. Together, this tool opens opportunities towards safer long-sequence genome engineering. Wang, Qu et al. developed a genome-editing system, utilizing catalytically inactive Cas9 fused to microbial single-strand annealing proteins, for kilobase-scale insertion in human cells without introducing DNA nicks or breaks.
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12
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Nambiar TS, Baudrier L, Billon P, Ciccia A. CRISPR-based genome editing through the lens of DNA repair. Mol Cell 2022; 82:348-388. [PMID: 35063100 PMCID: PMC8887926 DOI: 10.1016/j.molcel.2021.12.026] [Citation(s) in RCA: 76] [Impact Index Per Article: 38.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 01/22/2023]
Abstract
Genome editing technologies operate by inducing site-specific DNA perturbations that are resolved by cellular DNA repair pathways. Products of genome editors include DNA breaks generated by CRISPR-associated nucleases, base modifications induced by base editors, DNA flaps created by prime editors, and integration intermediates formed by site-specific recombinases and transposases associated with CRISPR systems. Here, we discuss the cellular processes that repair CRISPR-generated DNA lesions and describe strategies to obtain desirable genomic changes through modulation of DNA repair pathways. Advances in our understanding of the DNA repair circuitry, in conjunction with the rapid development of innovative genome editing technologies, promise to greatly enhance our ability to improve food production, combat environmental pollution, develop cell-based therapies, and cure genetic and infectious diseases.
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Affiliation(s)
- Tarun S Nambiar
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Lou Baudrier
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada
| | - Pierre Billon
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, 3330 Hospital Drive N.W., Calgary, Alberta T2N 4N1, Canada.
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY 10032, USA.
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13
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Wolter F, Schindele P, Beying N, Scheben A, Puchta H. Different DNA repair pathways are involved in single-strand break-induced genomic changes in plants. THE PLANT CELL 2021; 33:3454-3469. [PMID: 34375428 PMCID: PMC8566284 DOI: 10.1093/plcell/koab204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/04/2021] [Indexed: 05/03/2023]
Abstract
In nature, single-strand breaks (SSBs) in DNA occur more frequently (by orders of magnitude) than double-strand breaks (DSBs). SSBs induced by the CRISPR/Cas9 nickase at a distance of 50-100 bp on opposite strands are highly mutagenic, leading to insertions/deletions (InDels), with insertions mainly occurring as direct tandem duplications. As short tandem repeats are overrepresented in plant genomes, this mechanism seems to be important for genome evolution. We investigated the distance at which paired 5'-overhanging SSBs are mutagenic and which DNA repair pathways are essential for insertion formation in Arabidopsis thaliana. We were able to detect InDel formation up to a distance of 250 bp, although with much reduced efficiency. Surprisingly, the loss of the classical nonhomologous end joining (NHEJ) pathway factors KU70 or DNA ligase 4 completely abolished tandem repeat formation. The microhomology-mediated NHEJ factor POLQ was required only for patch-like insertions, which are well-known from DSB repair as templated insertions from ectopic sites. As SSBs can also be repaired using homology, we furthermore asked whether the classical homologous recombination (HR) pathway is involved in this process in plants. The fact that RAD54 is not required for homology-mediated SSB repair demonstrates that the mechanisms for DSB- and SSB-induced HR differ in plants.
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Affiliation(s)
- Felix Wolter
- Botanical Institute, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Patrick Schindele
- Botanical Institute, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Natalja Beying
- Botanical Institute, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
| | - Armin Scheben
- Simons Center for Quantitative Biology, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA
| | - Holger Puchta
- Botanical Institute, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany
- Author for correspondence:
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14
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Cantor SB. Revisiting the BRCA-pathway through the lens of replication gap suppression: "Gaps determine therapy response in BRCA mutant cancer". DNA Repair (Amst) 2021; 107:103209. [PMID: 34419699 PMCID: PMC9049047 DOI: 10.1016/j.dnarep.2021.103209] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 08/06/2021] [Accepted: 08/07/2021] [Indexed: 12/12/2022]
Abstract
The toxic lesion emanating from chemotherapy that targets the DNA was initially debated, but eventually the DNA double strand break (DSB) ultimately prevailed. The reasoning was in part based on the perception that repairing a fractured chromosome necessitated intricate processing or condemned the cell to death. Genetic evidence for the DSB model was also provided by the extreme sensitivity of cells that were deficient in DSB repair. In particular, sensitivity characterized cells harboring mutations in the hereditary breast/ovarian cancer genes, BRCA1 or BRCA2, that function in the repair of DSBs by homologous recombination (HR). Along with functions in HR, BRCA proteins were found to prevent DSBs by protecting stalled replication forks from nuclease degradation. Coming full-circle, BRCA mutant cancer cells that gained resistance to genotoxic chemotherapy often displayed restored DNA repair by HR and/or restored fork protection (FP) implicating that the therapy was tolerated when DSB repair was intact or DSBs were prevented. Despite this well-supported paradigm that has been the impetus for targeted cancer therapy, here we argue that the toxic DNA lesion conferring response is instead single stranded DNA (ssDNA) gaps. We discuss the evidence that persistent ssDNA gaps formed in the wake of DNA replication rather than DSBs are responsible for cell killing following treatment with genotoxic chemotherapeutic agents. We also highlight that proteins, such as BRCA1, BRCA2, and RAD51 known for canonical DSB repair also have critical roles in normal replication as well as replication gap suppression (RGS) and repair. We review the literature that supports the idea that widespread gap induction proximal to treatment triggers apoptosis in a process that does not need or stem from DSB induction. Lastly, we discuss the clinical evidence for gaps and how to exploit them to enhance genotoxic chemotherapy response.
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Affiliation(s)
- Sharon B Cantor
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, LRB 415, 364 Plantation St., Worcester, MA 01605, USA.
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15
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Aquino-Jarquin G. Current advances in overcoming obstacles of CRISPR/Cas9 off-target genome editing. Mol Genet Metab 2021; 134:77-86. [PMID: 34391646 DOI: 10.1016/j.ymgme.2021.08.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 08/03/2021] [Accepted: 08/03/2021] [Indexed: 12/14/2022]
Abstract
CRISPR/Cas9-based technology has revolutionized biomedical research by providing a high-fidelity gene-editing method, foreshadowing a significant impact on the therapeutics of many human genetic disorders previously considered untreatable. However, off-target events represent a critical hurdle before genome editing can be fully established in clinical practice. This mini-review recapitulates some recent advances for detecting and overcoming off-target effects mediated by the CRISPR/Cas9 system that could increase the likelihood of clinical success of the CRISPR-based approaches.
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Affiliation(s)
- Guillermo Aquino-Jarquin
- Laboratorio de Investigación en Genómica, Genética y Bioinformática, Hospital Infantil de México, Federico Gómez, Ciudad de México, Mexico; Departamento de Ciencias Naturales, Unidad Cuajimalpa, Universidad Autónoma Metropolitana, Ciudad de México, Mexico.
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16
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Poggi L, Emmenegger L, Descorps-Declère S, Dumas B, Richard GF. Differential efficacies of Cas nucleases on microsatellites involved in human disorders and associated off-target mutations. Nucleic Acids Res 2021; 49:8120-8134. [PMID: 34233005 PMCID: PMC8373144 DOI: 10.1093/nar/gkab569] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 06/11/2021] [Accepted: 07/06/2021] [Indexed: 11/13/2022] Open
Abstract
Microsatellite expansions are the cause of >20 neurological or developmental human disorders. Shortening expanded repeats using specific DNA endonucleases may be envisioned as a gene editing approach. Here, we measured the efficacy of several CRISPR-Cas nucleases to induce recombination within disease-related microsatellites, in Saccharomyces cerevisiae. Broad variations in nuclease performances were detected on all repeat tracts. Wild-type Streptococcus pyogenes Cas9 (SpCas9) was more efficient than Staphylococcus aureus Cas9 on all repeats tested, except (CAG)33. Cas12a (Cpf1) was the most efficient on GAA trinucleotide repeats, whereas GC-rich repeats were more efficiently cut by SpCas9. The main genetic factor underlying Cas efficacy was the propensity of the recognition part of the sgRNA to form a stable secondary structure, independently of its structural part. This suggests that such structures form in vivo and interfere with sgRNA metabolism. The yeast genome contains 221 natural CAG/CTG and GAA/CTT trinucleotide repeats. Deep sequencing after nuclease induction identified three of them as carrying statistically significant low frequency mutations, corresponding to SpCas9 off-target double-strand breaks.
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Affiliation(s)
- Lucie Poggi
- Institut Pasteur, CNRS, UMR3525, 25 rue du Dr Roux, F-75015 Paris, France.,Sorbonne Université, Collège Doctoral, 4 Place Jussieu, F-75005 Paris, France.,Biologics Research, Sanofi R&D, 13 Quai Jules Guesde, 94403 Vitry sur Seine, France
| | - Lisa Emmenegger
- Institut Pasteur, CNRS, UMR3525, 25 rue du Dr Roux, F-75015 Paris, France
| | - Stéphane Descorps-Declère
- Institut Pasteur, CNRS, UMR3525, 25 rue du Dr Roux, F-75015 Paris, France.,Institut Pasteur, Bioinformatics and Biostatistics Hub, Department of Computational Biology, USR3756 CNRS, F-75015 Paris, France
| | - Bruno Dumas
- Biologics Research, Sanofi R&D, 13 Quai Jules Guesde, 94403 Vitry sur Seine, France
| | - Guy-Franck Richard
- Institut Pasteur, CNRS, UMR3525, 25 rue du Dr Roux, F-75015 Paris, France.,Sorbonne Université, Collège Doctoral, 4 Place Jussieu, F-75005 Paris, France
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17
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Penth M, Schellnhuber K, Bennewitz R, Blass J. Nanomechanics of self-assembled DNA building blocks. NANOSCALE 2021; 13:9371-9380. [PMID: 33999986 DOI: 10.1039/d0nr06865a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
DNA has become a powerful platform to design functional nanodevices. DNA nanodevices are often composed of self-assembled DNA building blocks that differ significantly from the structure of native DNA. In this study, we present Flow Force Microscopy as a massively parallel approach to study the nanomechanics of DNA self-assemblies on the single-molecular level. The high-throughput experiments performed in a simple microfluidic channel enable statistically meaningful studies with nanometer scale precision in a time frame of several minutes. A surprisingly high flexibility was observed for a typical construct used in DNA origami, reflected in a persistence length of 10.2 nm, a factor of five smaller than for native DNA. The enhanced flexibility is attributed to the discontinuous backbone of DNA self-assemblies that facilitate base pair opening by thermal fluctuations at the end of hybridized oligomers. We believe that the results will contribute to the fundamental understanding of DNA nanomechanics and help to improve the design of DNA nanodevices with applications in biological analysis and clinical research.
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Affiliation(s)
- Michael Penth
- INM - Leibniz Institute for New Materials, Campus D22, 66123 Saarbrücken, Germany. and Physics Department, Campus D22, 66123 Saarbrücken, Germany
| | - Kordula Schellnhuber
- INM - Leibniz Institute for New Materials, Campus D22, 66123 Saarbrücken, Germany. and Physics Department, Campus D22, 66123 Saarbrücken, Germany
| | - Roland Bennewitz
- INM - Leibniz Institute for New Materials, Campus D22, 66123 Saarbrücken, Germany. and Physics Department, Campus D22, 66123 Saarbrücken, Germany
| | - Johanna Blass
- INM - Leibniz Institute for New Materials, Campus D22, 66123 Saarbrücken, Germany.
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18
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Zhang Y, Davis L, Maizels N. Pathways and signatures of mutagenesis at targeted DNA nicks. PLoS Genet 2021; 17:e1009329. [PMID: 33857147 PMCID: PMC8078790 DOI: 10.1371/journal.pgen.1009329] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/27/2021] [Accepted: 03/16/2021] [Indexed: 12/19/2022] Open
Abstract
Nicks are the most frequent form of DNA damage and a potential source of mutagenesis in human cells. By deep sequencing, we have identified factors and pathways that promote and limit mutagenic repair at a targeted nick in human cells. Mutations were distributed asymmetrically around the nick site. BRCA2 inhibited all categories of mutational events, including indels, SNVs and HDR. DNA2 and RPA promoted resection. DNA2 inhibited 1 bp deletions but contributed to longer deletions, as did REV7. POLQ stimulated SNVs. Parallel analysis of DSBs targeted to the same site identified similar roles for DNA2 and POLQ (but not REV7) in promoting deletions and for POLQ in stimulating SNVs. Insertions were infrequent at nicks, and most were 1 bp in length, as at DSBs. The translesion polymerase REV1 stimulated +1 insertions at one nick site but not another, illustrating the potential importance of sequence context in determining the outcome of mutagenic repair. These results highlight the potential for nicks to promote mutagenesis, especially in BRCA-deficient cells, and identify mutagenic signatures of DNA2, REV1, REV3, REV7 and POLQ.
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Affiliation(s)
- Yinbo Zhang
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
| | - Luther Davis
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
| | - Nancy Maizels
- Department of Immunology, University of Washington Medical School, Seattle, Washington, United States of America
- Department of Biochemistry, University of Washington Medical School, Seattle, Washington, United States of America
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19
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Hughes NW, Cong L. A CRISPR Landing for Genome Rewriting at Locus-Scale. CRISPR J 2021; 4:163-166. [PMID: 33876954 DOI: 10.1089/crispr.2021.29124.lec] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Nicholas W Hughes
- Department of Pathology and Wu Tsai Neuroscience Institute, Stanford Cancer Institute, Stanford University School of Medicine, 265 Campus Dr, Stanford, CA 94305, USA. .,Department of Genetics, Wu Tsai Neuroscience Institute, Stanford Cancer Institute, Stanford University School of Medicine, 265 Campus Dr, Stanford, CA 94305, USA.
| | - Le Cong
- Department of Pathology and Wu Tsai Neuroscience Institute, Stanford Cancer Institute, Stanford University School of Medicine, 265 Campus Dr, Stanford, CA 94305, USA. .,Department of Genetics, Wu Tsai Neuroscience Institute, Stanford Cancer Institute, Stanford University School of Medicine, 265 Campus Dr, Stanford, CA 94305, USA.
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20
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Direct unfolding of RuvA-HJ complex at the single-molecule level. Biophys J 2021; 120:1894-1902. [PMID: 33737156 DOI: 10.1016/j.bpj.2021.03.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Revised: 03/03/2021] [Accepted: 03/09/2021] [Indexed: 11/20/2022] Open
Abstract
The repair of double-stranded DNA breaks via homologous recombination involves a four-way cross-strand intermediate known as Holliday junction (HJ), which is recognized, processed, and resolved by a specific set of proteins. RuvA, a prokaryotic HJ-binding protein, is known to stabilize the square-planar conformation of the HJ, which is otherwise a short-lived intermediate. Despite much progress being made regarding the molecular mechanism of RuvA-HJ interactions, the mechanochemical aspect of this protein-HJ complex is yet to be investigated. Here, we employed an optical-tweezers-based, single-molecule manipulation assay to detect the formation of RuvA-HJ complex and determined its mechanical and thermodynamic properties in a manner that would be impossible with traditional ensemble techniques. We found that the binding of RuvA increases the unfolding force (Funfold) of the HJ by ∼2-fold. Compared with the ΔGunfold of the HJ alone (54 ± 13 kcal/mol), the increased free energy of the RuvA-HJ complex (101 ± 20 kcal/mol) demonstrates that the RuvA protein stabilizes HJs. Interestingly, the protein remains bound to the mechanically melted HJ, facilitating its refolding at an unusually high force when the stretched DNA molecule is relaxed. These results suggest that the RuvA protein not only stabilizes the HJs but also induces refolding of the HJs. The single-molecule platform that we employed here for studying the RuvA-HJ interaction is broadly applicable to study other HJ-binding proteins involved in the critical DNA repair process.
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21
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Akkaya Ö, Aparicio T, Pérez-Pantoja D, de Lorenzo V. The faulty SOS response of Pseudomonas putida KT2440 stems from an inefficient RecA-LexA interplay. Environ Microbiol 2021; 23:1608-1619. [PMID: 33393180 DOI: 10.1111/1462-2920.15384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2020] [Revised: 12/28/2020] [Accepted: 12/29/2020] [Indexed: 11/29/2022]
Abstract
Despite its environmental robustness Pseudomonas putida strain KT2440 is very sensitive to DNA damage and displays poor homologous recombination efficiencies. To gain an insight into this deficiency isogenic ∆recA and ∆lexA1 derivatives of prophage-free strain P. putida EM173 were generated and responses of the recA and lexA1 promoters to DNA damage tested with GFP reporter technology. Basal expression of recA and lexA1 of P. putida were high in the absence of DNA damage and only moderately induced by norfloxacin. A similar behaviour was observed when equivalent GFP fusions to the recA and lexA promoters of E. coli were placed in P. putida EM173. In contrast, all SOS promoters were subject to strong repression in E. coli, which was released only when cells were treated with the antibiotic. Replacement of P. putida's native LexA1 and RecA by E. coli homologues did not improve the responsiveness of the indigenous functions to DNA damage. Taken together, it seems that P. putida fails to mount a strong SOS response due to the inefficacy of the crucial RecA-LexA interplay largely tractable to the weakness of the corresponding promoters and the inability of the repressor to shut them down entirely in the absence of DNA damage.
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Affiliation(s)
- Özlem Akkaya
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, 28049, Spain.,Department of Molecular Biology and Genetics, Gebze Technical University, Kocaeli, Turkey
| | - Tomás Aparicio
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, 28049, Spain
| | - Danilo Pérez-Pantoja
- Programa Institucional de Fomento a la Investigación, Desarrollo e Innovación (PIDi), Universidad Tecnológica Metropolitana, Santiago, Chile
| | - Víctor de Lorenzo
- Systems Biology Program, Centro Nacional de Biotecnología (CNB-CSIC), Campus de Cantoblanco, Madrid, 28049, Spain
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22
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Bosch JA, Birchak G, Perrimon N. Precise genome engineering in Drosophila using prime editing. Proc Natl Acad Sci U S A 2021; 118:e2021996118. [PMID: 33443210 PMCID: PMC7817132 DOI: 10.1073/pnas.2021996118] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Precise genome editing is a valuable tool to study gene function in model organisms. Prime editing, a precise editing system developed in mammalian cells, does not require double-strand breaks or donor DNA and has low off-target effects. Here, we applied prime editing for the model organism Drosophila melanogaster and developed conditions for optimal editing. By expressing prime editing components in cultured cells or somatic cells of transgenic flies, we precisely introduce premature stop codons in three classical visible marker genes, ebony, white, and forked Furthermore, by restricting editing to germ cells, we demonstrate efficient germ-line transmission of a precise edit in ebony to 36% of progeny. Our results suggest that prime editing is a useful system in Drosophila to study gene function, such as engineering precise point mutations, deletions, or epitope tags.
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Affiliation(s)
- Justin A Bosch
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115;
| | - Gabriel Birchak
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115
| | - Norbert Perrimon
- Department of Genetics, Blavatnik Institute, Harvard Medical School, Boston, MA 02115;
- HHMI, Harvard Medical School, Boston, MA 02115
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23
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Kim HJ, Oh SY, Lee SJ. Single-Base Genome Editing in Corynebacterium glutamicum with the Help of Negative Selection by Target-Mismatched CRISPR/Cpf1. J Microbiol Biotechnol 2020; 30:1583-1591. [PMID: 32807756 PMCID: PMC9728170 DOI: 10.4014/jmb.2006.06036] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 08/09/2020] [Accepted: 08/10/2020] [Indexed: 12/15/2022]
Abstract
CRISPR/Cpf1 has emerged as a new CRISPR-based genome editing tool because, in comparison with CRIPSR/Cas9, it has a different T-rich PAM sequence to expand the target DNA sequence. Single-base editing in the microbial genome can be facilitated by oligonucleotide-directed mutagenesis (ODM) followed by negative selection with the CRISPR/Cpf1 system. However, single point mutations aided by Cpf1 negative selection have been rarely reported in Corynebacterium glutamicum. This study aimed to introduce an amber stop codon in crtEb encoding lycopene hydratase, through ODM and Cpf1-mediated negative selection; deficiency of this enzyme causes pink coloration due to lycopene accumulation in C. glutamicum. Consequently, on using double-, triple-, and quadruple-basemutagenic oligonucleotides, 91.5-95.3% pink cells were obtained among the total live C. glutamicum cells. However, among the negatively selected live cells, 0.6% pink cells were obtained using single-base-mutagenic oligonucleotides, indicating that very few single-base mutations were introduced, possibly owing to mismatch tolerance. This led to the consideration of various targetmismatched crRNAs to prevent the death of single-base-edited cells. Consequently, we obtained 99.7% pink colonies after CRISPR/Cpf1-mediated negative selection using an appropriate singlemismatched crRNA. Furthermore, Sanger sequencing revealed that single-base mutations were successfully edited in the 99.7% of pink cells, while only two of nine among 0.6% of pink cells were correctly edited. The results indicate that the target-mismatched Cpf1 negative selection can assist in efficient and accurate single-base genome editing methods in C. glutamicum.
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Affiliation(s)
- Hyun Ju Kim
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
| | - Se Young Oh
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea
| | - Sang Jun Lee
- Department of Systems Biotechnology, Chung-Ang University, Anseong 17546, Republic of Korea,Corresponding author Phone: +82-31-670-3356 E-mail:
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24
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Li S, Shi B, Liu X, An HX. Acetylation and Deacetylation of DNA Repair Proteins in Cancers. Front Oncol 2020; 10:573502. [PMID: 33194676 PMCID: PMC7642810 DOI: 10.3389/fonc.2020.573502] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Hundreds of DNA repair proteins coordinate together to remove the diverse damages for ensuring the genomic integrity and stability. The repair system is an extensive network mainly encompassing cell cycle arrest, chromatin remodeling, various repair pathways, and new DNA fragment synthesis. Acetylation on DNA repair proteins is a dynamic epigenetic modification orchestrated by lysine acetyltransferases (HATs) and lysine deacetylases (HDACs), which dramatically affects the protein functions through multiple mechanisms, such as regulation of DNA binding ability, protein activity, post-translational modification (PTM) crosstalk, and protein–protein interaction. Accumulating evidence has indicated that the aberrant acetylation of DNA repair proteins contributes to the dysfunction of DNA repair ability, the pathogenesis and progress of cancer, as well as the chemosensitivity of cancer cells. In the present scenario, targeting epigenetic therapy is being considered as a promising method at par with the conventional cancer therapeutic strategies. This present article provides an overview of the recent progress in the functions and mechanisms of acetylation on DNA repair proteins involved in five major repair pathways, which warrants the possibility of regulating acetylation on repair proteins as a therapeutic target in cancers.
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Affiliation(s)
- Shiqin Li
- Department of Medical Oncology, Xiang'an Hospital of Xiamen University, Xiamen, China
| | - Bingbing Shi
- Department of Medical Oncology, Xiang'an Hospital of Xiamen University, Xiamen, China
| | - Xinli Liu
- Department of Medical Oncology, Xiang'an Hospital of Xiamen University, Xiamen, China
| | - Han-Xiang An
- Department of Medical Oncology, Xiang'an Hospital of Xiamen University, Xiamen, China
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25
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Davis L, Khoo KJ, Zhang Y, Maizels N. POLQ suppresses interhomolog recombination and loss of heterozygosity at targeted DNA breaks. Proc Natl Acad Sci U S A 2020; 117:22900-22909. [PMID: 32873648 PMCID: PMC7502765 DOI: 10.1073/pnas.2008073117] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Interhomolog recombination (IHR) occurs spontaneously in somatic human cells at frequencies that are low but sufficient to ameliorate some genetic diseases caused by heterozygous mutations or autosomal dominant mutations. Here we demonstrate that DNA nicks or double-strand breaks (DSBs) targeted by CRISPR-Cas9 to both homologs can stimulate IHR and associated copy-neutral loss of heterozygosity (cnLOH) in human cells. The frequency of IHR is 10-fold lower at nicks than at DSBs, but cnLOH is evident in a greater fraction of recombinants. IHR at DSBs occurs predominantly via reciprocal end joining. At DSBs, depletion of POLQ caused a dramatic increase in IHR and in the fraction of recombinants exhibiting cnLOH, suggesting that POLQ promotes end joining in cis, which limits breaks available for recombination in trans These results define conditions that may produce cnLOH as a mutagenic signature in cancer and may, conversely, promote therapeutic correction of both compound heterozygous and dominant negative mutations associated with genetic disease.
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Affiliation(s)
- Luther Davis
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195
| | - Kevin J Khoo
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195
| | - Yinbo Zhang
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195
| | - Nancy Maizels
- Department of Immunology, University of Washington School of Medicine, Seattle, WA 98195;
- Department of Biochemistry, University of Washington School of Medicine, Seattle, WA 98195
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26
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Swiatczak B. Genomic Stress Responses Drive Lymphocyte Evolvability: An Ancient and Ubiquitous Mechanism. Bioessays 2020; 42:e2000032. [PMID: 32767393 DOI: 10.1002/bies.202000032] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 07/03/2020] [Indexed: 12/15/2022]
Abstract
Somatic diversification of antigen receptor genes depends on the activity of enzymes whose homologs participate in a mutagenic DNA repair in unicellular species. Indeed, by engaging error-prone polymerases, gap filling molecules and altered mismatch repair pathways, lymphocytes utilize conserved components of genomic stress response systems, which can already be found in bacteria and archaea. These ancient systems of mutagenesis and repair act to increase phenotypic diversity of microbial cell populations and operate to enhance their ability to produce fit variants during stress. Coopted by lymphocytes, the ancient mutagenic processing systems retained their diversification functions instilling the adaptive immune cells with enhanced evolvability and defensive capacity to resist infection and damage. As reviewed here, the ubiquity and conserved character of specialized variation-generating mechanisms from bacteria to lymphocytes highlight the importance of these mechanisms for evolution of life in general.
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Affiliation(s)
- Bartlomiej Swiatczak
- Department of History of Science and Scientific Archeology, University of Science and Technology of China, 96 Jinzhai Rd., Hefei, 230026, China
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27
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28
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Strand with mutagenic lesion is preferentially used as a template in the region of a bi-stranded clustered DNA damage site in Escherichia coli. Sci Rep 2020; 10:9737. [PMID: 32546758 PMCID: PMC7297740 DOI: 10.1038/s41598-020-66651-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 05/20/2020] [Indexed: 11/08/2022] Open
Abstract
The damaging potential of ionizing radiation arises largely from the generation of clustered DNA damage sites within cells. Previous studies using synthetic DNA lesions have demonstrated that models of clustered DNA damage exhibit enhanced mutagenic potential of the comprising lesions. However, little is known regarding the processes that lead to mutations in these sites, apart from the fact that base excision repair of lesions within the cluster is compromised. Unique features of the mutation frequencies within bi-stranded clusters have led researchers to speculate that the strand containing the mutagenic lesion is preferentially used as the template for DNA synthesis. To gain further insights into the processing of clustered DNA damage sites, we used a plasmid-based assay in E. coli cells. Our findings revealed that the strand containing a mutagenic lesion within a bi-stranded clustered DNA damage site is frequently used as the template. This suggests the presence of an, as yet unknown, strand synthesis process that is unrelated to base excision repair, and that this process plays an important role in mutagenesis. The length of the region of strand preference was found to be determined by DNA polymerase I.
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Qin Z, Bi L, Hou XM, Zhang S, Zhang X, Lu Y, Li M, Modesti M, Xi XG, Sun B. Human RPA activates BLM's bidirectional DNA unwinding from a nick. eLife 2020; 9:54098. [PMID: 32101168 PMCID: PMC7065910 DOI: 10.7554/elife.54098] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 02/25/2020] [Indexed: 01/12/2023] Open
Abstract
BLM is a multifunctional helicase that plays critical roles in maintaining genome stability. It processes distinct DNA substrates, but not nicked DNA, during many steps in DNA replication and repair. However, how BLM prepares itself for diverse functions remains elusive. Here, using a combined single-molecule approach, we find that a high abundance of BLMs can indeed unidirectionally unwind dsDNA from a nick when an external destabilizing force is applied. Strikingly, human replication protein A (hRPA) not only ensures that limited quantities of BLMs processively unwind nicked dsDNA under a reduced force but also permits the translocation of BLMs on both intact and nicked ssDNAs, resulting in a bidirectional unwinding mode. This activation necessitates BLM targeting on the nick and the presence of free hRPAs in solution whereas direct interactions between them are dispensable. Our findings present novel DNA unwinding activities of BLM that potentially facilitate its function switching in DNA repair.
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Affiliation(s)
- Zhenheng Qin
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xi-Miao Hou
- College of Life Sciences, Northwest A&F University, Yangling, China
| | - Siqi Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.,Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ying Lu
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Ming Li
- University of Chinese Academy of Sciences, Beijing, China.,Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Mauro Modesti
- Cancer Research Center of Marseille, CNRS UMR7258, Inserm U1068, Institut Paoli-Calmettes, Aix-Marseille Université, Marseille, France
| | - Xu-Guang Xi
- The LBPA, Ecole Normale Supérieure Paris-Saclay, CNRS, Université Paris Saclay, Gif-sur-Yvette, France
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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30
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Rees HA, Yeh WH, Liu DR. Development of hRad51-Cas9 nickase fusions that mediate HDR without double-stranded breaks. Nat Commun 2019; 10:2212. [PMID: 31101808 PMCID: PMC6525190 DOI: 10.1038/s41467-019-09983-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 04/04/2019] [Indexed: 12/20/2022] Open
Abstract
In mammalian cells, double-stranded DNA breaks (DSBs) are preferentially repaired through end-joining processes that generally lead to mixtures of insertions and deletions (indels) or other rearrangements at the cleavage site. In the presence of homologous DNA, homology-directed repair (HDR) can generate specific mutations, albeit typically with modest efficiency and a low ratio of HDR products:indels. Here, we develop hRad51 mutants fused to Cas9(D10A) nickase (RDN) that mediate HDR while minimizing indels. We use RDN to install disease-associated point mutations in HEK293T cells with comparable or better efficiency than Cas9 nuclease and a 2.7-to-53-fold higher ratio of desired HDR product:undesired byproducts. Across five different human cell types, RDN variants generally result in higher HDR:indel ratios and lower off-target activity than Cas9 nuclease, although HDR efficiencies remain strongly site- and cell type-dependent. RDN variants provide precision editing options in cell types amenable to HDR, especially when byproducts of DSBs must be minimized.
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Affiliation(s)
- Holly A Rees
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Wei-Hsi Yeh
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
- Program in Speech and Hearing Bioscience and Technology, Harvard Medical School, Boston, MA, 02115, USA
| | - David R Liu
- Merkin Institute of Transformative Technologies in Healthcare, Broad Institute of Harvard and MIT, Cambridge, MA, 02142, USA.
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA, 02142, USA.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA.
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31
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Hossain MA, Lin Y, Yan S. Single-Strand Break End Resection in Genome Integrity: Mechanism and Regulation by APE2. Int J Mol Sci 2018; 19:ijms19082389. [PMID: 30110897 PMCID: PMC6122073 DOI: 10.3390/ijms19082389] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/07/2018] [Accepted: 08/11/2018] [Indexed: 12/22/2022] Open
Abstract
DNA single-strand breaks (SSBs) occur more than 10,000 times per mammalian cell each day, representing the most common type of DNA damage. Unrepaired SSBs compromise DNA replication and transcription programs, leading to genome instability. Unrepaired SSBs are associated with diseases such as cancer and neurodegenerative disorders. Although canonical SSB repair pathway is activated to repair most SSBs, it remains unclear whether and how unrepaired SSBs are sensed and signaled. In this review, we propose a new concept of SSB end resection for genome integrity. We propose a four-step mechanism of SSB end resection: SSB end sensing and processing, as well as initiation, continuation, and termination of SSB end resection. We also compare different mechanisms of SSB end resection and DSB end resection in DNA repair and DNA damage response (DDR) pathways. We further discuss how SSB end resection contributes to SSB signaling and repair. We focus on the mechanism and regulation by APE2 in SSB end resection in genome integrity. Finally, we identify areas of future study that may help us gain further mechanistic insight into the process of SSB end resection. Overall, this review provides the first comprehensive perspective on SSB end resection in genome integrity.
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Affiliation(s)
- Md Akram Hossain
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
| | - Yunfeng Lin
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
| | - Shan Yan
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, NC 28223, USA.
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