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Sfeir A, Tijsterman M, McVey M. Microhomology-Mediated End-Joining Chronicles: Tracing the Evolutionary Footprints of Genome Protection. Annu Rev Cell Dev Biol 2024; 40:195-218. [PMID: 38857538 DOI: 10.1146/annurev-cellbio-111822-014426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2024]
Abstract
The fidelity of genetic information is essential for cellular function and viability. DNA double-strand breaks (DSBs) pose a significant threat to genome integrity, necessitating efficient repair mechanisms. While the predominant repair strategies are usually accurate, paradoxically, error-prone pathways also exist. This review explores recent advances and our understanding of microhomology-mediated end joining (MMEJ), an intrinsically mutagenic DSB repair pathway conserved across organisms. Central to MMEJ is the activity of DNA polymerase theta (Polθ), a specialized polymerase that fuels MMEJ mutagenicity. We examine the molecular intricacies underlying MMEJ activity and discuss its function during mitosis, where the activity of Polθ emerges as a last-ditch effort to resolve persistent DSBs, especially when homologous recombination is compromised. We explore the promising therapeutic applications of targeting Polθ in cancer treatment and genome editing. Lastly, we discuss the evolutionary consequences of MMEJ, highlighting its delicate balance between protecting genome integrity and driving genomic diversity.
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Affiliation(s)
- Agnel Sfeir
- Molecular Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, USA;
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center; Institute of Biology Leiden, Leiden University, Leiden, The Netherlands;
| | - Mitch McVey
- Department of Biology, Tufts University, Medford, Massachusetts, USA;
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2
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Yu Y, Wang X, Fox J, Li Q, Yu Y, Hastings PJ, Chen K, Ira G. RPA and Rad27 limit templated and inverted insertions at DNA breaks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.07.583931. [PMID: 38496432 PMCID: PMC10942419 DOI: 10.1101/2024.03.07.583931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Formation of templated insertions at DNA double-strand breaks (DSBs) is very common in cancer cells. The mechanisms and enzymes regulating these events are largely unknown. Here, we investigated templated insertions in yeast at DSBs using amplicon sequencing across a repaired locus. We document very short (most ∼5-34 bp), templated inverted duplications at DSBs. They are generated through a foldback mechanism that utilizes microhomologies adjacent to the DSB. Enzymatic requirements suggest a hybrid mechanism wherein one end requires Polδ-mediated synthesis while the other end is captured by nonhomologous end joining (NHEJ). This process is exacerbated in mutants with low levels or mutated RPA ( rtt105 Δ; rfa1 -t33) or extensive resection mutant ( sgs1 Δ exo1 Δ). Templated insertions from various distant genomic locations also increase in these mutants as well as in rad27 Δ and originate from fragile regions of the genome. Among complex insertions, common events are insertions of two sequences, originating from the same locus and with inverted orientation. We propose that these inversions are also formed by microhomology-mediated template switching. Taken together, we propose that a shortage of RPA typical in cancer cells is one possible factor stimulating the formation of templated insertions.
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3
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Al-Zain AM, Nester MR, Ahmed I, Symington LS. Double-strand breaks induce inverted duplication chromosome rearrangements by a DNA polymerase δ-dependent mechanism. Nat Commun 2023; 14:7020. [PMID: 37919272 PMCID: PMC10622511 DOI: 10.1038/s41467-023-42640-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2023] [Accepted: 10/17/2023] [Indexed: 11/04/2023] Open
Abstract
Inverted duplications, also known as foldback inversions, are commonly observed in cancers and are the major class of chromosome rearrangement recovered from yeast cells lacking Mre11 nuclease activity. Foldback priming at DNA double-strand breaks (DSBs) is one mechanism proposed for the generation of inverted duplications. However, the other pathway steps have not been fully elucidated. Here, we show that a DSB induced near natural inverted repeats drives high frequency inverted duplication in Sae2 and Mre11-deficient cells. We find that DNA polymerase δ proof-reading activity, but not Rad1 nuclease, trims the heterologous flaps formed after foldback annealing. Additionally, Pol32 is required for the generation of inverted duplications, suggesting that Pol δ catalyzes fill-in synthesis primed from the foldback to create a hairpin-capped chromosome that is subsequently replicated to form a dicentric inversion chromosome. Finally, we show that stabilization of the dicentric chromosome after breakage involves telomere capture by non-reciprocal translocation mediated by repeat sequences or by deletion of one centromere.
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Affiliation(s)
- Amr M Al-Zain
- Program in Biological Sciences, Columbia University, New York, NY, 10027, USA
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Mattie R Nester
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Iffat Ahmed
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, USA.
- Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, 10032, USA.
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4
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Stroik S, Carvajal-Garcia J, Gupta D, Edwards A, Luthman A, Wyatt DW, Dannenberg RL, Feng W, Kunkel TA, Gupta GP, Hedglin M, Wood R, Doublié S, Rothenberg E, Ramsden DA. Stepwise requirements for polymerases δ and θ in theta-mediated end joining. Nature 2023; 623:836-841. [PMID: 37968395 PMCID: PMC10959172 DOI: 10.1038/s41586-023-06729-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 10/06/2023] [Indexed: 11/17/2023]
Abstract
Timely repair of chromosomal double-strand breaks is required for genome integrity and cellular viability. The polymerase theta-mediated end joining pathway has an important role in resolving these breaks and is essential in cancers defective in other DNA repair pathways, thus making it an emerging therapeutic target1. It requires annealing of 2-6 nucleotides of complementary sequence, microhomologies, that are adjacent to the broken ends, followed by initiation of end-bridging DNA synthesis by polymerase θ. However, the other pathway steps remain inadequately defined, and the enzymes required for them are unknown. Here we demonstrate requirements for exonucleolytic digestion of unpaired 3' tails before polymerase θ can initiate synthesis, then a switch to a more accurate, processive and strand-displacing polymerase to complete repair. We show the replicative polymerase, polymerase δ, is required for both steps; its 3' to 5' exonuclease activity for flap trimming, then its polymerase activity for extension and completion of repair. The enzymatic steps that are essential and specific to this pathway are mediated by two separate, sequential engagements of the two polymerases. The requisite coupling of these steps together is likely to be facilitated by physical association of the two polymerases. This pairing of polymerase δ with a polymerase capable of end-bridging synthesis, polymerase θ, may help to explain why the normally high-fidelity polymerase δ participates in genome destabilizing processes such as mitotic DNA synthesis2 and microhomology-mediated break-induced replication3.
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Affiliation(s)
- Susanna Stroik
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Dipika Gupta
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Alyssa Edwards
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Adam Luthman
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - David W Wyatt
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Rachel L Dannenberg
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Wanjuan Feng
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Thomas A Kunkel
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
| | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Mark Hedglin
- Department of Chemistry, The Pennsylvania State University, University Park, PA, USA
| | - Richard Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center and The University of Texas MD Anderson Cancer Center UT Health Graduate School of Biomedical Sciences, Houston, TX, USA
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT, USA
| | - Eli Rothenberg
- Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY, USA
| | - Dale A Ramsden
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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5
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Shaltz S, Jinks-Robertson S. Genetic control of the error-prone repair of a chromosomal double-strand break with 5' overhangs in yeast. Genetics 2023; 225:iyad122. [PMID: 37418686 PMCID: PMC10471200 DOI: 10.1093/genetics/iyad122] [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: 05/03/2023] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 07/09/2023] Open
Abstract
A targeted double-strand break introduced into the genome of Saccharomyces cerevisiae is repaired by the relatively error-prone nonhomologous end joining (NHEJ) pathway when homologous recombination is not an option. A zinc finger nuclease cleavage site was inserted out-of-frame into the LYS2 locus of a haploid yeast strain to study the genetic control of NHEJ when the ends contain 5' overhangs. Repair events that destroyed the cleavage site were identified either as Lys+ colonies on selective medium or as surviving colonies on rich medium. Junction sequences in Lys+ events solely reflected NHEJ and were influenced by the nuclease activity of Mre11 as well as by the presence/absence of the NHEJ-specific polymerase Pol4 and the translesion-synthesis DNA polymerases Pol ζ and Pol η. Although most NHEJ events were dependent on Pol4, a 29-bp deletion with endpoints in 3-bp repeats was an exception. The Pol4-independent deletion required translesion synthesis polymerases as well as the exonuclease activity of the replicative Pol δ DNA polymerase. Survivors were equally split between NHEJ events and 1.2 or 11.7 kb deletions that reflected microhomology-mediated end joining (MMEJ). MMEJ events required the processive resection activity of Exo1/Sgs1, but there unexpectedly was no dependence on the Rad1-Rad10 endonuclease for the removal of presumptive 3' tails. Finally, NHEJ was more efficient in nongrowing than in growing cells and was most efficient in G0 cells. These studies provide novel insights into the flexibility and complexity of error-prone DSB repair in yeast.
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Affiliation(s)
- Samantha Shaltz
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
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6
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Cerqueira PG, Meyer D, Zhang L, Mallory B, Liu J, Hua Fu BX, Zhang X, Heyer WD. Saccharomyces cerevisiae DNA polymerase IV overcomes Rad51 inhibition of DNA polymerase δ in Rad52-mediated direct-repeat recombination. Nucleic Acids Res 2023; 51:5547-5564. [PMID: 37070185 PMCID: PMC10287921 DOI: 10.1093/nar/gkad281] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 03/29/2023] [Accepted: 04/06/2023] [Indexed: 04/19/2023] Open
Abstract
Saccharomyces cerevisiae DNA polymerase IV (Pol4) like its homolog, human DNA polymerase lambda (Polλ), is involved in Non-Homologous End-Joining and Microhomology-Mediated Repair. Using genetic analysis, we identified an additional role of Pol4 also in homology-directed DNA repair, specifically in Rad52-dependent/Rad51-independent direct-repeat recombination. Our results reveal that the requirement for Pol4 in repeat recombination was suppressed by the absence of Rad51, suggesting that Pol4 counteracts the Rad51 inhibition of Rad52-mediated repeat recombination events. Using purified proteins and model substrates, we reconstituted in vitro reactions emulating DNA synthesis during direct-repeat recombination and show that Rad51 directly inhibits Polδ DNA synthesis. Interestingly, although Pol4 was not capable of performing extensive DNA synthesis by itself, it aided Polδ in overcoming the DNA synthesis inhibition by Rad51. In addition, Pol4 dependency and stimulation of Polδ DNA synthesis in the presence of Rad51 occurred in reactions containing Rad52 and RPA where DNA strand-annealing was necessary. Mechanistically, yeast Pol4 displaces Rad51 from ssDNA independent of DNA synthesis. Together our in vitro and in vivo data suggest that Rad51 suppresses Rad52-dependent/Rad51-independent direct-repeat recombination by binding to the primer-template and that Rad51 removal by Pol4 is critical for strand-annealing dependent DNA synthesis.
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Affiliation(s)
- Paula G Cerqueira
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Damon Meyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Lilin Zhang
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Benjamin Mallory
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Jie Liu
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Becky Xu Hua Fu
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Xiaoping Zhang
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
- Department of Molecular and Cellular Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616-8665, USA
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7
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Shaltz S, Jinks-Robertson S. Genetic control of the error-prone repair of a chromosomal double-strand break with 5' overhangs in yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.04.539391. [PMID: 37205473 PMCID: PMC10187297 DOI: 10.1101/2023.05.04.539391] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A targeted double-strand break introduced into the genome of Saccharomyces cerevisiae is repaired by the relatively error-prone nonhomologous-end joining (NHEJ) pathway when homologous recombination is not an option. A ZFN cleavage site was inserted out-of-frame into the LYS2 locus of a haploid yeast strain to study the genetic control of NHEJ when the ends contain 5' overhangs. Repair events that destroyed the cleavage site were identified either as Lys + colonies on selective medium or as surviving colonies on rich medium. Junction sequences in Lys + events solely reflected NHEJ and were influenced by the nuclease activity of Mre11 as well as by the presence/absence of the NHEJ-specific polymerase Pol4 and the translesion-synthesis DNA polymerases Pol σ and Pol 11. Although most NHEJ events were dependent on Pol4, a 29-bp deletion with endpoints in 3-bp repeats was an exception. The Pol4-independent deletion required TLS polymerases as well as the exonuclease activity of the replicative Pol DNA polymerase. Survivors were equally split between NHEJ events and 1 kb or 11 kb deletions that reflected microhomology-mediated end joining (MMEJ). MMEJ events required the processive resection activity of Exo1/Sgs1, but there unexpectedly was no dependence on the Rad1-Rad10 endonuclease for the removal of presumptive 3' tails. Finally, NHEJ was more efficient in non-growing than in growing cells and was most efficient in G0 cells. These studies provide novel insight into the flexibility and complexity of error-prone DSB repair in yeast.
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Affiliation(s)
- Samantha Shaltz
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710
| | - Sue Jinks-Robertson
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710
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8
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Al-Zain A, Nester MR, Symington LS. Double-strand breaks induce inverted duplication chromosome rearrangements by a DNA polymerase δ and Rad51-dependent mechanism. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525421. [PMID: 36747747 PMCID: PMC9900772 DOI: 10.1101/2023.01.24.525421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Inverted duplications, also known as foldback inversions, are commonly observed in cancers and are the major class of chromosome rearrangement recovered from yeast cells lacking Mre11 nuclease. Foldback priming at naturally occurring inverted repeats is one mechanism proposed for the generation of inverted duplications. However, the initiating lesion for these events and the mechanism by which they form has not been fully elucidated. Here, we show that a DNA double-strand break (DSB) induced near natural short, inverted repeats drives high frequency inverted duplication in Sae2 and Mre11-deficient cells. We find that DNA polymerase δ proof-reading activity acts non-redundantly with Rad1 nuclease to remove heterologous tails formed during foldback annealing. Additionally, Pol32 is required for the generation of inverted duplications, suggesting that Pol δ catalyzes fill-in synthesis primed from the foldback to create a hairpin-capped chromosome that is subsequently replicated to form a dicentric isochromosome. Stabilization of the dicentric chromosome after breakage involves telomere capture by non-reciprocal translocation mediated by repeat sequences and requires Rad51.
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9
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Huang J, Cook DE. The contribution of DNA repair pathways to genome editing and evolution in filamentous pathogens. FEMS Microbiol Rev 2022; 46:fuac035. [PMID: 35810003 PMCID: PMC9779921 DOI: 10.1093/femsre/fuac035] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 06/29/2022] [Accepted: 07/06/2022] [Indexed: 01/09/2023] Open
Abstract
DNA double-strand breaks require repair or risk corrupting the language of life. To ensure genome integrity and viability, multiple DNA double-strand break repair pathways function in eukaryotes. Two such repair pathways, canonical non-homologous end joining and homologous recombination, have been extensively studied, while other pathways such as microhomology-mediated end joint and single-strand annealing, once thought to serve as back-ups, now appear to play a fundamental role in DNA repair. Here, we review the molecular details and hierarchy of these four DNA repair pathways, and where possible, a comparison for what is known between animal and fungal models. We address the factors contributing to break repair pathway choice, and aim to explore our understanding and knowledge gaps regarding mechanisms and regulation in filamentous pathogens. We additionally discuss how DNA double-strand break repair pathways influence genome engineering results, including unexpected mutation outcomes. Finally, we review the concept of biased genome evolution in filamentous pathogens, and provide a model, termed Biased Variation, that links DNA double-strand break repair pathways with properties of genome evolution. Despite our extensive knowledge for this universal process, there remain many unanswered questions, for which the answers may improve genome engineering and our understanding of genome evolution.
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Affiliation(s)
- Jun Huang
- Department of Plant Pathology, Kansas State University, 1712 Claflin Road, Throckmorton Hall, Manhattan, KS 66506, United States
| | - David E Cook
- Department of Plant Pathology, Kansas State University, 1712 Claflin Road, Throckmorton Hall, Manhattan, KS 66506, United States
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10
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Zhao M, Gao M, Xiong L, Liu Y, Tao X, Gao B, Liu M, Wang FQ, Wei DZ. CRISPR-Cas Assisted Shotgun Mutagenesis Method for Evolutionary Genome Engineering. ACS Synth Biol 2022; 11:1958-1970. [PMID: 35500195 DOI: 10.1021/acssynbio.2c00112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genome mutagenesis drives the evolution of organisms. Here, we developed a CRISPR-Cas assisted random mutation (CARM) technique for whole-genome mutagenesis. The method leverages an entirely random gRNA library and SpCas9-NG to randomly damage genomes in a controllable shotgunlike manner that then triggers diverse and abundant mutations via low-fidelity repair. As a proof of principle, CARM was applied to evolve the capacity of Saccharomyces cerevisiae BY4741 to produce β-carotene. After seven rounds of iterative evolution over two months, a β-carotene hyperproducing strain, C7-143, was isolated with a 10.5-fold increase in β-carotene production and 857 diverse genomic mutations that comprised indels, duplications, inversions, and chromosomal rearrangements. Transcriptomic analysis revealed that the expression of 2541 genes of strain C7-143 was significantly altered, suggesting that the metabolic landscape of the strain was deeply reconstructed. In addition, CARM was applied to evolve industrially relevant S. cerevisiae CEN.PK2-1C for S-adenosyl-L-methionine production, which was increased 2.28 times after just one round. Thus, CARM can contribute to increasing genetic diversity to identify new phenotypes that could further be investigated by reverse engineering.
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Affiliation(s)
- Ming Zhao
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
- Anhui Engineering Laboratory for Industrial Microbiology Molecular Breeding, College of Biological and Food Engineering, Anhui Polytechnic University, Wuhu 241000, China
| | - Miaomiao Gao
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Liangbin Xiong
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
- Shanghai Key Laboratory of Molecular Imaging, Shanghai University of Medicine and Health Sciences, Shanghai 201318, China
| | - Yongjun Liu
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Xinyi Tao
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Bei Gao
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Min Liu
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Feng-Qing Wang
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
| | - Dong-Zhi Wei
- State Key Laboratory of Bioreactor Engineering, Newworld Institute of Biotechnology, East China University of Science and Technology, 130 Meilong Road, Shanghai 200237, China
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11
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Bai W, Zhao B, Gu M, Dong J. Alternative end-joining in BCR gene rearrangements and translocations. Acta Biochim Biophys Sin (Shanghai) 2022; 54:782-795. [PMID: 35593472 PMCID: PMC9828324 DOI: 10.3724/abbs.2022051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Programmed DNA double-strand breaks (DSBs) occur during antigen receptor gene recombination, namely V(D)J recombination in developing B lymphocytes and class switch recombination (CSR) in mature B cells. Repair of these DSBs by classical end-joining (c-NHEJ) enables the generation of diverse BCR repertoires for efficient humoral immunity. Deletion of or mutation in c-NHEJ genes in mice and humans confer various degrees of primary immune deficiency and predisposition to lymphoid malignancies that often harbor oncogenic chromosomal translocations. In the absence of c-NHEJ, alternative end-joining (A-EJ) catalyzes robust CSR and to a much lesser extent, V(D)J recombination, but the mechanisms of A-EJ are only poorly defined. In this review, we introduce recent advances in the understanding of A-EJ in the context of V(D)J recombination and CSR with emphases on DSB end processing, DNA polymerases and ligases, and discuss the implications of A-EJ to lymphoid development and chromosomal translocations.
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Affiliation(s)
- Wanyu Bai
- Department of ImmunologyZhongshan School of MedicineSun Yat-sen UniversityGuangzhou510080China,Key Laboratory of Tropical Disease Control (Sun Yat-sen University)Ministry of EducationGuangzhou510080China
| | - Bo Zhao
- Department of ImmunologyZhongshan School of MedicineSun Yat-sen UniversityGuangzhou510080China,Key Laboratory of Tropical Disease Control (Sun Yat-sen University)Ministry of EducationGuangzhou510080China
| | - Mingyu Gu
- Department of ImmunologyZhongshan School of MedicineSun Yat-sen UniversityGuangzhou510080China,Key Laboratory of Tropical Disease Control (Sun Yat-sen University)Ministry of EducationGuangzhou510080China
| | - Junchao Dong
- Department of ImmunologyZhongshan School of MedicineSun Yat-sen UniversityGuangzhou510080China,Key Laboratory of Tropical Disease Control (Sun Yat-sen University)Ministry of EducationGuangzhou510080China,Correspondence address. Tel: +86-20-87330571; E-mail:
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12
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Modulating DNA Repair Pathways to Diversify Genomic Alterations in Saccharomyces cerevisiae. Microbiol Spectr 2022; 10:e0232621. [PMID: 35352941 PMCID: PMC9045378 DOI: 10.1128/spectrum.02326-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Nuclease based genome editing systems have emerged as powerful tools to drive genomic alterations and enhance genome evolution via precise engineering in the various human and microbial cells. However, error-prone DNA repair has not been well studied previously to generate diverse genomic alterations and novel phenotypes. Here, we systematically investigated the potential interplay between DNA double strand break (DSB) repair and genome editing tools, and found that modulating the DSB end resection proteins could significantly improve mutational efficiency and diversity without exogenous DNA template in yeast. Deleting SAE2, EXO1, or FUN30, or overexpressing MRE11-H125N (nuclease-dead allele of MRE11), for DSB end resection markedly increased the efficiency of CRISPR/SpCas9 (more than 22-fold) and CRISPR/AsCpf1 (more than 30-fold)-induced mutagenesis. Deleting SAE2 or overexpressing MRE11-H125N substantially diversified CRISPR/SpCas9 or AsCpf1-induced mutation 2–3-fold at URA3 locus, and 3–5-fold at ADE2 locus. Thus, the error-prone DNA repair protein was employed to develop a novel mutagenic genome editing (mGE) strategy, which can increase the mutation numbers and effectively improve the ethanol/glycerol ratio of Saccharomyces cerevisiae through modulating the expression of FPS1 and GPD1. This study highlighted the feasibility of potentially reshaping the capability of genome editing by regulating the different DSB repair proteins and can thus expand the application of genome editing in diversifying gene expression and enhancing genome evolution. IMPORTANCE Most of the published papers about nuclease-assisted genome editing focused on precision engineering in human cells. However, the topic of inducing mutagenesis via error-prone repair has often been ignored in yeast. In this study, we reported that perturbing DNA repair, especially modifications of the various DSB end resection-related proteins, could greatly improve the mutational efficiency and diversity, and thus functionally reshape the capability of the different genome editing tools without requiring an exogenous DNA template in yeast. Specifically, mutagenic genome editing (mGE) was developed based on CRISPR/AsCpf1 and MRE11-H125N overexpression, and used to generate promoters of different strengths more efficiently. Thus, this work provides a novel method to diversify gene expression and enhance genome evolution.
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13
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Ramsden DA, Carvajal-Garcia J, Gupta GP. Mechanism, cellular functions and cancer roles of polymerase-theta-mediated DNA end joining. Nat Rev Mol Cell Biol 2022; 23:125-140. [PMID: 34522048 DOI: 10.1038/s41580-021-00405-2] [Citation(s) in RCA: 87] [Impact Index Per Article: 43.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/21/2021] [Indexed: 02/08/2023]
Abstract
Cellular pathways that repair chromosomal double-strand breaks (DSBs) have pivotal roles in cell growth, development and cancer. These DSB repair pathways have been the target of intensive investigation, but one pathway - alternative end joining (a-EJ) - has long resisted elucidation. In this Review, we highlight recent progress in our understanding of a-EJ, especially the assignment of DNA polymerase theta (Polθ) as the predominant mediator of a-EJ in most eukaryotes, and discuss a potential molecular mechanism by which Polθ-mediated end joining (TMEJ) occurs. We address possible cellular functions of TMEJ in resolving DSBs that are refractory to repair by non-homologous end joining (NHEJ), DSBs generated following replication fork collapse and DSBs present owing to stalling of repair by homologous recombination. We also discuss how these context-dependent cellular roles explain how TMEJ can both protect against and cause genome instability, and the emerging potential of Polθ as a therapeutic target in cancer.
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Affiliation(s)
- Dale A Ramsden
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Juan Carvajal-Garcia
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Radiation Oncology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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14
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Bordelet H, Costa R, Brocas C, Dépagne J, Veaute X, Busso D, Batté A, Guérois R, Marcand S, Dubrana K. Sir3 heterochromatin protein promotes non-homologous end joining by direct inhibition of Sae2. EMBO J 2022; 41:e108813. [PMID: 34817085 PMCID: PMC8724767 DOI: 10.15252/embj.2021108813] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 01/07/2023] Open
Abstract
Heterochromatin is a conserved feature of eukaryotic chromosomes, with central roles in gene expression regulation and maintenance of genome stability. How heterochromatin proteins regulate DNA repair remains poorly described. In the yeast Saccharomyces cerevisiae, the silent information regulator (SIR) complex assembles heterochromatin-like chromatin at sub-telomeric chromosomal regions. SIR-mediated repressive chromatin limits DNA double-strand break (DSB) resection, thus protecting damaged chromosome ends during homologous recombination (HR). As resection initiation represents the crossroads between repair by non-homologous end joining (NHEJ) or HR, we asked whether SIR-mediated heterochromatin regulates NHEJ. We show that SIRs promote NHEJ through two pathways, one depending on repressive chromatin assembly, and the other relying on Sir3 in a manner that is independent of its heterochromatin-promoting function. Via physical interaction with the Sae2 protein, Sir3 impairs Sae2-dependent functions of the MRX (Mre11-Rad50-Xrs2) complex, thereby limiting Mre11-mediated resection, delaying MRX removal from DSB ends, and promoting NHEJ.
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Affiliation(s)
- Hélène Bordelet
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Régulation spatiale des génomes, Institut Pasteur, CNRS UMR3525ParisFrance
| | - Rafaël Costa
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Clémentine Brocas
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Jordane Dépagne
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Xavier Veaute
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Didier Busso
- CIGEx platform. Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Amandine Batté
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
- Center for Integrative GenomicsBâtiment GénopodeUniversity of LausanneLausanneSwitzerland
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC)CEA, CNRS, Université Paris‐Sud, Université Paris‐SaclayGif‐sur‐YvetteFrance
| | - Stéphane Marcand
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
| | - Karine Dubrana
- Université de Paris and Université Paris‐Saclay, INSERM, iRCM/IBFJ CEA, UMR Stabilité Génétique Cellules Souches et RadiationsFontenay‐aux‐RosesFrance
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15
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Clay DE, Fox DT. DNA Damage Responses during the Cell Cycle: Insights from Model Organisms and Beyond. Genes (Basel) 2021; 12:1882. [PMID: 34946831 PMCID: PMC8701014 DOI: 10.3390/genes12121882] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/22/2021] [Accepted: 11/23/2021] [Indexed: 12/25/2022] Open
Abstract
Genome damage is a threat to all organisms. To respond to such damage, DNA damage responses (DDRs) lead to cell cycle arrest, DNA repair, and cell death. Many DDR components are highly conserved, whereas others have adapted to specific organismal needs. Immense progress in this field has been driven by model genetic organism research. This review has two main purposes. First, we provide a survey of model organism-based efforts to study DDRs. Second, we highlight how model organism study has contributed to understanding how specific DDRs are influenced by cell cycle stage. We also look forward, with a discussion of how future study can be expanded beyond typical model genetic organisms to further illuminate how the genome is protected.
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Affiliation(s)
- Delisa E. Clay
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA;
| | - Donald T. Fox
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA;
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
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16
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Bai W, Zhu G, Xu J, Chen P, Meng F, Xue H, Chen C, Dong J. The 3'-flap endonuclease XPF-ERCC1 promotes alternative end joining and chromosomal translocation during B cell class switching. Cell Rep 2021; 36:109756. [PMID: 34592150 DOI: 10.1016/j.celrep.2021.109756] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 07/06/2021] [Accepted: 09/02/2021] [Indexed: 11/17/2022] Open
Abstract
Robust alternative end joining (A-EJ) in classical non-homologous end joining (c-NHEJ)-deficient murine cells features double-strand break (DSB) end resection and microhomology (MH) usage and promotes chromosomal translocation. The activities responsible for removing 3' single-strand overhangs following resection and MH annealing in A-EJ remain unclear. We show that, during class switch recombination (CSR) in mature mouse B cells, the structure-specific endonuclease complex XPF-ERCC1SLX4, although not required for normal CSR, represents a nucleotide-excision-repair-independent 3' flap removal activity for A-EJ-mediated CSR. B cells deficient in DNA ligase 4 and XPF-ERCC1 exhibit further impaired class switching, reducing joining to the resected S region DSBs without altering the MH pattern in S-S junctions. In ERCC1-deficient A-EJ cells, 3' single-stranded DNA (ssDNA) flaps that are generated predominantly in S/G2 phase of the cell cycle are susceptible to nuclease resolution. Moreover, ERCC1 promotes c-myc-IgH translocation in Lig4-/- cells. Our study reveals an important role of the flap endonuclease XPF-ERCC1 in A-EJ and oncogenic translocation in mouse B cells.
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Affiliation(s)
- Wanyu Bai
- Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Guangchao Zhu
- Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Jiejie Xu
- Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Pingyue Chen
- Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China
| | - Feilong Meng
- State Key Laboratory of Molecular Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Hongman Xue
- Department of Pediatrics, the Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong 518107, China
| | - Chun Chen
- Department of Pediatrics, the Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong 518107, China.
| | - Junchao Dong
- Department of Immunology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou 510080, China; Key Laboratory of Tropical Disease Control (Sun Yat-sen University), Ministry of Education, Guangzhou, China; Department of Pediatrics, the Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, Guangdong 518107, China.
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17
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Al-Zain AM, Symington LS. The dark side of homology-directed repair. DNA Repair (Amst) 2021; 106:103181. [PMID: 34311272 DOI: 10.1016/j.dnarep.2021.103181] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/16/2021] [Accepted: 07/16/2021] [Indexed: 10/20/2022]
Abstract
DNA double strand breaks (DSB) are cytotoxic lesions that can lead to genome rearrangements and genomic instability, which are hallmarks of cancer. The two main DSB repair pathways are non-homologous end joining and homologous recombination (HR). While HR is generally highly accurate, it has the potential for rearrangements that occur directly or through intermediates generated during the repair process. Whole genome sequencing of cancers has revealed numerous types of structural rearrangement signatures that are often indicative of repair mediated by sequence homology. However, it can be challenging to delineate repair mechanisms from sequence analysis of rearrangement end products from cancer genomes, or even model systems, because the same rearrangements can be generated by different pathways. Here, we review homology-directed repair pathways and their consequences. Exploring those pathways can lead to a greater understanding of rearrangements that occur in cancer cells.
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Affiliation(s)
- Amr M Al-Zain
- Program in Biological Sciences, Columbia University, New York, NY, 10027, United States; Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY, 10032, United States; Department of Genetics & Development, Columbia University Irving Medical Center, New York, NY, 10032, United States.
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18
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Replication-independent instability of Friedreich's ataxia GAA repeats during chronological aging. Proc Natl Acad Sci U S A 2021; 118:2013080118. [PMID: 33495349 PMCID: PMC7865128 DOI: 10.1073/pnas.2013080118] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The inheritance of long (GAA)n repeats in the frataxin gene causes the debilitating neurodegenerative disease Friedreich’s ataxia. Subsequent expansions of these repeats throughout a patient’s lifetime in the affected tissues, like the nervous system, may contribute to disease onset. We developed an experimental model to characterize the mechanisms of repeat instability in nondividing cells to better understand how mutations can occur as cells age chronologically. We show that repeats can expand in nondividing cells. Notably, however, large deletions are the major type of repeat-mediated genome instability in nondividing cells, implicating the loss of important genetic material with aging in the progression of Friedreich’s ataxia. Nearly 50 hereditary diseases result from the inheritance of abnormally long repetitive DNA microsatellites. While it was originally believed that the size of inherited repeats is the key factor in disease development, it has become clear that somatic instability of these repeats throughout an individual’s lifetime strongly contributes to disease onset and progression. Importantly, somatic instability is commonly observed in terminally differentiated, postmitotic cells, such as neurons. To unravel the mechanisms of repeat instability in nondividing cells, we created an experimental system to analyze the mutability of Friedreich’s ataxia (GAA)n repeats during chronological aging of quiescent Saccharomyces cerevisiae. Unexpectedly, we found that the predominant repeat-mediated mutation in nondividing cells is large-scale deletions encompassing parts, or the entirety, of the repeat and adjacent regions. These deletions are caused by breakage at the repeat mediated by mismatch repair (MMR) complexes MutSβ and MutLα and DNA endonuclease Rad1, followed by end-resection by Exo1 and repair of the resulting double-strand breaks (DSBs) via nonhomologous end joining. We also observed repeat-mediated gene conversions as a result of DSB repair via ectopic homologous recombination during chronological aging. Repeat expansions accrue during chronological aging as well—particularly in the absence of MMR-induced DSBs. These expansions depend on the processivity of DNA polymerase δ while being counteracted by Exo1 and MutSβ, implicating nick repair. Altogether, these findings show that the mechanisms and types of (GAA)n repeat instability differ dramatically between dividing and nondividing cells, suggesting that distinct repeat-mediated mutations in terminally differentiated somatic cells might influence Friedreich’s ataxia pathogenesis.
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19
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Van Vu T, Thi Hai Doan D, Kim J, Sung YW, Thi Tran M, Song YJ, Das S, Kim J. CRISPR/Cas-based precision genome editing via microhomology-mediated end joining. PLANT BIOTECHNOLOGY JOURNAL 2021; 19:230-239. [PMID: 33047464 PMCID: PMC7868975 DOI: 10.1111/pbi.13490] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/11/2020] [Accepted: 10/03/2020] [Indexed: 05/05/2023]
Abstract
Gene editing and/or allele introgression with absolute precision and control appear to be the ultimate goals of genetic engineering. Precision genome editing in plants has been developed through various approaches, including oligonucleotide-directed mutagenesis (ODM), base editing, prime editing and especially homologous recombination (HR)-based gene targeting. With the advent of CRISPR/Cas for the targeted generation of DNA breaks (single-stranded breaks (SSBs) or double-stranded breaks (DSBs)), a substantial advancement in HR-mediated precise editing frequencies has been achieved. Nonetheless, further research needs to be performed for commercially viable applications of precise genome editing; hence, an alternative innovative method for genome editing may be required. Within this scope, we summarize recent progress regarding precision genome editing mediated by microhomology-mediated end joining (MMEJ) and discuss their potential applications in crop improvement.
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Affiliation(s)
- Tien Van Vu
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
- National Key Laboratory for Plant Cell BiotechnologyAgricultural Genetics InstituteKm 02, Pham Van Dong RoadCo Nhue 1, Bac Tu Liem, Hanoi11917Vietnam
| | - Duong Thi Hai Doan
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Jihae Kim
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Yeon Woo Sung
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Mil Thi Tran
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Young Jong Song
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Swati Das
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
| | - Jae‐Yean Kim
- Division of Applied Life Science (BK21 Plus Program)Plant Molecular Biology and Biotechnology Research CenterGyeongsang National UniversityJinju 660‐701Republic of Korea
- Division of Life ScienceGyeongsang National University501 Jinju‐daeroJinju52828Republic of Korea
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20
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Gribble J, Stevens LJ, Agostini ML, Anderson-Daniels J, Chappell JD, Lu X, Pruijssers AJ, Routh AL, Denison MR. The coronavirus proofreading exoribonuclease mediates extensive viral recombination. PLoS Pathog 2021; 17:e1009226. [PMID: 33465137 PMCID: PMC7846108 DOI: 10.1371/journal.ppat.1009226] [Citation(s) in RCA: 156] [Impact Index Per Article: 52.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 01/29/2021] [Accepted: 12/08/2020] [Indexed: 12/14/2022] Open
Abstract
Recombination is proposed to be critical for coronavirus (CoV) diversity and emergence of SARS-CoV-2 and other zoonotic CoVs. While RNA recombination is required during normal CoV replication, the mechanisms and determinants of CoV recombination are not known. CoVs encode an RNA proofreading exoribonuclease (nsp14-ExoN) that is distinct from the CoV polymerase and is responsible for high-fidelity RNA synthesis, resistance to nucleoside analogues, immune evasion, and virulence. Here, we demonstrate that CoVs, including SARS-CoV-2, MERS-CoV, and the model CoV murine hepatitis virus (MHV), generate extensive and diverse recombination products during replication in culture. We show that the MHV nsp14-ExoN is required for native recombination, and that inactivation of ExoN results in decreased recombination frequency and altered recombination products. These results add yet another critical function to nsp14-ExoN, highlight the uniqueness of the evolved coronavirus replicase, and further emphasize nsp14-ExoN as a central, completely conserved, and vulnerable target for inhibitors and attenuation of SARS-CoV-2 and future emerging zoonotic CoVs.
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Affiliation(s)
- Jennifer Gribble
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4), Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Laura J. Stevens
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Maria L. Agostini
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Jordan Anderson-Daniels
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - James D. Chappell
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Xiaotao Lu
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Andrea J. Pruijssers
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
| | - Andrew L. Routh
- Department of Biochemistry and Molecular Biology, University of Texas–Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Structural Biology and Molecular Biophysics, University of Texas–Medical Branch, Galveston, Texas, United States of America
| | - Mark R. Denison
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Vanderbilt Institute for Infection, Immunology, and Inflammation (VI4), Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
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21
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Polymerase δ promotes chromosomal rearrangements and imprecise double-strand break repair. Proc Natl Acad Sci U S A 2020; 117:27566-27577. [PMID: 33077594 DOI: 10.1073/pnas.2014176117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Recent studies have implicated DNA polymerases θ (Pol θ) and β (Pol β) as mediators of alternative nonhomologous end-joining (Alt-NHEJ) events, including chromosomal translocations. Here we identify subunits of the replicative DNA polymerase δ (Pol δ) as promoters of Alt-NHEJ that results in more extensive intrachromosomal mutations at a single double-strand break (DSB) and more frequent translocations between two DSBs. Depletion of the Pol δ accessory subunit POLD2 destabilizes the complex, resulting in degradation of both POLD1 and POLD3 in human cells. POLD2 depletion markedly reduces the frequency of translocations with sequence modifications but does not affect the frequency of translocations with exact joins. Using separation-of-function mutants, we show that both the DNA synthesis and exonuclease activities of the POLD1 subunit contribute to translocations. As described in yeast and unlike Pol θ, Pol δ also promotes homology-directed repair. Codepletion of POLD2 with 53BP1 nearly eliminates translocations. POLD1 and POLD2 each colocalize with phosphorylated H2AX at ionizing radiation-induced DSBs but not with 53BP1. Codepletion of POLD2 with either ligase 3 (LIG3) or ligase 4 (LIG4) does not further reduce translocation frequency compared to POLD2 depletion alone. Together, these data support a model in which Pol δ promotes Alt-NHEJ in human cells at DSBs, including translocations.
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22
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Wu ZJ, Liu JC, Man X, Gu X, Li TY, Cai C, He MH, Shao Y, Lu N, Xue X, Qin Z, Zhou JQ. Cdc13 is predominant over Stn1 and Ten1 in preventing chromosome end fusions. eLife 2020; 9:53144. [PMID: 32755541 PMCID: PMC7406354 DOI: 10.7554/elife.53144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 06/12/2020] [Indexed: 12/16/2022] Open
Abstract
Telomeres define the natural ends of eukaryotic chromosomes and are crucial for chromosomal stability. The budding yeast Cdc13, Stn1 and Ten1 proteins form a heterotrimeric complex, and the inactivation of any of its subunits leads to a uniformly lethal phenotype due to telomere deprotection. Although Cdc13, Stn1 and Ten1 seem to belong to an epistasis group, it remains unclear whether they function differently in telomere protection. Here, we employed the single-linear-chromosome yeast SY14, and surprisingly found that the deletion of CDC13 leads to telomere erosion and intrachromosome end-to-end fusion, which depends on Rad52 but not Yku. Interestingly, the emergence frequency of survivors in the SY14 cdc13Δ mutant was ~29 fold higher than that in either the stn1Δ or ten1Δ mutant, demonstrating a predominant role of Cdc13 in inhibiting telomere fusion. Chromosomal fusion readily occurred in the telomerase-null SY14 strain, further verifying the default role of intact telomeres in inhibiting chromosome fusion.
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Affiliation(s)
- Zhi-Jing Wu
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Jia-Cheng Liu
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Xin Man
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Xin Gu
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Ting-Yi Li
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Chen Cai
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Ming-Hong He
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Yangyang Shao
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Ning Lu
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Xiaoli Xue
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Zhongjun Qin
- Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China
| | - Jin-Qiu Zhou
- The State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences; University of Chinese Academy of Sciences, Shanghai, China.,School of Life Science and Technology, ShanghaiTech University, Shanghai, China
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23
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Hanscom T, McVey M. Regulation of Error-Prone DNA Double-Strand Break Repair and Its Impact on Genome Evolution. Cells 2020; 9:E1657. [PMID: 32660124 PMCID: PMC7407515 DOI: 10.3390/cells9071657] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/06/2020] [Accepted: 07/07/2020] [Indexed: 12/17/2022] Open
Abstract
Double-strand breaks are one of the most deleterious DNA lesions. Their repair via error-prone mechanisms can promote mutagenesis, loss of genetic information, and deregulation of the genome. These detrimental outcomes are significant drivers of human diseases, including many cancers. Mutagenic double-strand break repair also facilitates heritable genetic changes that drive organismal adaptation and evolution. In this review, we discuss the mechanisms of various error-prone DNA double-strand break repair processes and the cellular conditions that regulate them, with a focus on alternative end joining. We provide examples that illustrate how mutagenic double-strand break repair drives genome diversity and evolution. Finally, we discuss how error-prone break repair can be crucial to the induction and progression of diseases such as cancer.
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Affiliation(s)
| | - Mitch McVey
- Department. of Biology, Tufts University, Medford, MA 02155, USA;
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Contractions of the C-Terminal Domain of Saccharomyces cerevisiae Rpb1p Are Mediated by Rad5p. G3-GENES GENOMES GENETICS 2020; 10:2543-2551. [PMID: 32467128 PMCID: PMC7341143 DOI: 10.1534/g3.120.401409] [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: 11/25/2022]
Abstract
The C-terminal domain (CTD) is an essential domain of the largest subunit of RNA polymerase II, Rpb1p, and is composed of 26 tandem repeats of a seven-amino acid sequence, YSPTSPS. Despite being an essential domain within an essential gene, we have previously demonstrated that the CTD coding region is genetically unstable. Furthermore, yeast with a truncated or mutated CTD sequence are capable of promoting spontaneous genetic expansion or contraction of this coding region to improve fitness. We investigated the mechanism by which the CTD contracts using a tet-off reporter system for RPB1 to monitor genetic instability within the CTD coding region. We report that contractions require the post-replication repair factor Rad5p but, unlike expansions, not the homologous recombination factors Rad51p and Rad52p. Sequence analysis of contraction events reveals that deleted regions are flanked by microhomologies. We also find that G-quadruplex forming sequences predicted by the QGRS Mapper are enriched on the noncoding strand of the CTD compared to the body of RPB1. Formation of G-quadruplexes in the CTD coding region could block the replication fork, necessitating post-replication repair. We propose that contractions of the CTD result when microhomologies misalign during Rad5p-dependent template switching via fork reversal.
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25
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Deng Y, Guo W, Xu N, Li F, Li J. CtBP1 transactivates RAD51 and confers cisplatin resistance to breast cancer cells. Mol Carcinog 2020; 59:512-519. [PMID: 32124501 DOI: 10.1002/mc.23175] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 02/15/2020] [Accepted: 02/18/2020] [Indexed: 12/11/2022]
Abstract
Overexpression of RAD51 is found in many cancers including breast cancer and is associated with poor survival. Compared with normal cells, RAD51 promoter is hyperactive in cancer cells indicating that RAD51 is transcriptionally activated. However, little is known about the mechanisms and factors involved in RAD51 transcription regulation. Transcription corepressor, C-terminal binding protein 1 (CtBP1), is an oncogene repressing a panel of tumor suppressors transcription, which contributes to cancer progression. In this study, immunohistochemistry (IHC) revealed that RAD51 expression was positively correlated with CtBP1 expression in breast cancer patient tissues; short hairpin RNA-mediated CtBP1 depletion, chromatin immunoprecipitation, and dual-luciferase reporter assays showed that CtBP1 activated RAD51 transcription in breast cancer cells. Depletion of CtBP1 increased breast cancer cells' sensitivity to cisplatin and, in turn, expression of exogenous RAD51 in the CtBP1-depleted breast cancer cells increased resistance to cisplatin. The results demonstrated that CtBP1 conferred breast cancer cells resistance to cisplatin through transcriptional activation of RAD51.
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Affiliation(s)
- Yu Deng
- School of Medicine, Chengdu University, Chengdu, China.,Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, China
| | - Wanjun Guo
- Department of Dermatology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Ning Xu
- Department of Dermatology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Fulun Li
- Department of Dermatology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Affiliated with Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Jian Li
- School of Medicine, Chengdu University, Chengdu, China.,Institute of Cancer Biology and Drug Discovery, Chengdu University, Chengdu, China
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26
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Bosshard S, Duroy PO, Mermod N. A role for alternative end-joining factors in homologous recombination and genome editing in Chinese hamster ovary cells. DNA Repair (Amst) 2019; 82:102691. [PMID: 31476574 DOI: 10.1016/j.dnarep.2019.102691] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 08/13/2019] [Accepted: 08/14/2019] [Indexed: 12/22/2022]
Abstract
CRISPR technologies greatly foster genome editing in mammalian cells through site-directed DNA double strand breaks (DSBs). However, precise editing outcomes, as mediated by homologous recombination (HR) repair, are typically infrequent and outnumbered by undesired genome alterations. By using knockdown and overexpression studies in Chinese hamster ovary (CHO) cells as well as characterizing repaired DNA junctions, we found that efficient HR-mediated genome editing depends on alternative end-joining (alt-EJ) DNA repair activities, a family of incompletely characterized DNA repair pathways traditionally considered to oppose HR. This dependency was influenced by the CRISPR nuclease type and the DSB-to-mutation distance, but not by the DNA sequence surrounding the DSBs or reporter cell line. We also identified elevated Mre11 and Pari, and low Rad51 expression levels as the most rate-limiting factors for HR in CHO cells. Counteracting these three bottlenecks improved precise genome editing by up to 75%. Altogether, our study provides novel insights into the complex interplay of alt-EJ and HR repair pathways, highlighting their relevance for developing improved genome editing strategies.
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Affiliation(s)
- Sandra Bosshard
- Institute of Biotechnology and Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Pierre-Olivier Duroy
- Institute of Biotechnology and Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland
| | - Nicolas Mermod
- Institute of Biotechnology and Department of Fundamental Microbiology, University of Lausanne, 1015 Lausanne, Switzerland.
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27
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Cassani C, Gobbini E, Vertemara J, Wang W, Marsella A, Sung P, Tisi R, Zampella G, Longhese MP. Structurally distinct Mre11 domains mediate MRX functions in resection, end-tethering and DNA damage resistance. Nucleic Acids Res 2019; 46:2990-3008. [PMID: 29420790 PMCID: PMC5888019 DOI: 10.1093/nar/gky086] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 01/31/2018] [Indexed: 11/27/2022] Open
Abstract
Sae2 cooperates with the Mre11–Rad50-Xrs2 (MRX) complex to initiate resection of DNA double-strand breaks (DSBs) and to maintain the DSB ends in close proximity to allow their repair. How these diverse MRX-Sae2 functions contribute to DNA damage resistance is not known. Here, we describe mre11 alleles that suppress the hypersensitivity of sae2Δ cells to genotoxic agents. By assessing the impact of these mutations at the cellular and structural levels, we found that all the mre11 alleles that restore sae2Δ resistance to both camptothecin and phleomycin affect the Mre11 N-terminus and suppress the resection defect of sae2Δ cells by lowering MRX and Tel1 association to DSBs. As a consequence, the diminished Tel1 persistence potentiates Sgs1-Dna2 resection activity by decreasing Rad9 association to DSBs. By contrast, the mre11 mutations restoring sae2Δ resistance only to phleomycin are located in Mre11 C-terminus and bypass Sae2 function in end-tethering but not in DSB resection, possibly by destabilizing the Mre11–Rad50 open conformation. These findings unmask the existence of structurally distinct Mre11 domains that support resistance to genotoxic agents by mediating different processes.
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Affiliation(s)
- Corinne Cassani
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Elisa Gobbini
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Jacopo Vertemara
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Weibin Wang
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Antonio Marsella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Renata Tisi
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Giuseppe Zampella
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
| | - Maria Pia Longhese
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milano, Italy
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28
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Lee K, Ji JH, Yoon K, Che J, Seol JH, Lee SE, Shim EY. Microhomology Selection for Microhomology Mediated End Joining in Saccharomyces cerevisiae. Genes (Basel) 2019; 10:genes10040284. [PMID: 30965655 PMCID: PMC6523938 DOI: 10.3390/genes10040284] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 03/26/2019] [Accepted: 03/28/2019] [Indexed: 12/03/2022] Open
Abstract
Microhomology-mediated end joining (MMEJ) anneals short, imperfect microhomologies flanking DNA breaks, producing repair products with deletions in a Ku- and RAD52-independent fashion. Puzzlingly, MMEJ preferentially selects certain microhomologies over others, even when multiple microhomologies are available. To define rules and parameters for microhomology selection, we altered the length, the position, and the level of mismatches to the microhomologies flanking homothallic switching (HO) endonuclease-induced breaks and assessed their effect on MMEJ frequency and the types of repair product formation. We found that microhomology of eight to 20 base pairs carrying no more than 20% mismatches efficiently induced MMEJ. Deletion of MSH6 did not impact MMEJ frequency. MMEJ preferentially chose a microhomology pair that was more proximal from the break. Interestingly, MMEJ events preferentially retained the centromere proximal side of the HO break, while the sequences proximal to the telomere were frequently deleted. The asymmetry in the deletional profile among MMEJ products was reduced when HO was induced on the circular chromosome. The results provide insight into how cells search and select microhomologies for MMEJ in budding yeast.
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Affiliation(s)
- Kihoon Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Jae-Hoon Ji
- Genomic Instability Research Center, Ajou University School of Medicine. 164, World Cup-ro, Yeongtong-gu, Suwon 16499, Korea.
| | - Kihoon Yoon
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Jun Che
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Ja-Hwan Seol
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Sang Eun Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.
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Cooperation between non-essential DNA polymerases contributes to genome stability in Saccharomyces cerevisiae. DNA Repair (Amst) 2019; 76:40-49. [PMID: 30818168 DOI: 10.1016/j.dnarep.2019.02.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 02/04/2019] [Accepted: 02/05/2019] [Indexed: 11/21/2022]
Abstract
DNA polymerases influence genome stability through their involvement in DNA replication, response to DNA damage, and DNA repair processes. Saccharomyces cerevisiae possess four non-essential DNA polymerases, Pol λ, Pol η, Pol ζ, and Rev1, which have varying roles in genome stability. In order to assess the contribution of the non-essential DNA polymerases in genome stability, we analyzed the pol4Δ rev1Δ rev3Δ rad30Δ quadruple mutant in microhomology mediated repair, due to recent studies linking some of these DNA polymerases to this repair pathway. Our results suggest that the length and quality of microhomology influence both the overall efficiency of repair and the involvement of DNA polymerases. Furthermore, the non-essential DNA polymerases demonstrate overlapping and redundant functions when repairing double-strand breaks using short microhomologies containing mismatches. Then, we examined genome-wide mutation accumulation in the pol4Δ rev1Δ rev3Δ rad30Δ quadruple mutant compared to wild type cells. We found a significant decrease in the overall rate of mutation accumulation in the quadruple mutant cells compared to wildtype, but an increase in frameshift mutations and a shift towards transversion base-substitution with a preference for G:C to T:A or C:G. Thus, the non-essential DNA polymerases have an impact on the nature of the mutational spectrum. The sequence and functional homology shared between human and S. cerevisiae non-essential DNA polymerases suggest these DNA polymerases may have a similar role in human cells.
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30
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Oh J, Symington LS. Role of the Mre11 Complex in Preserving Genome Integrity. Genes (Basel) 2018; 9:E589. [PMID: 30501098 PMCID: PMC6315862 DOI: 10.3390/genes9120589] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 11/26/2018] [Accepted: 11/27/2018] [Indexed: 12/12/2022] Open
Abstract
DNA double-strand breaks (DSBs) are hazardous lesions that threaten genome integrity and cell survival. The DNA damage response (DDR) safeguards the genome by sensing DSBs, halting cell cycle progression and promoting repair through either non-homologous end joining (NHEJ) or homologous recombination (HR). The Mre11-Rad50-Xrs2/Nbs1 (MRX/N) complex is central to the DDR through its structural, enzymatic, and signaling roles. The complex tethers DNA ends, activates the Tel1/ATM kinase, resolves protein-bound or hairpin-capped DNA ends, and maintains telomere homeostasis. In addition to its role at DSBs, MRX/N associates with unperturbed replication forks, as well as stalled replication forks, to ensure complete DNA synthesis and to prevent chromosome rearrangements. Here, we summarize the significant progress made in characterizing the MRX/N complex and its various activities in chromosome metabolism.
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Affiliation(s)
- Julyun Oh
- Biological Sciences Program, Columbia University, New York, NY 10027, USA.
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
| | - Lorraine S Symington
- Department of Microbiology & Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA.
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31
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Paull TT. 20 Years of Mre11 Biology: No End in Sight. Mol Cell 2018; 71:419-427. [PMID: 30057197 DOI: 10.1016/j.molcel.2018.06.033] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 05/18/2018] [Accepted: 06/21/2018] [Indexed: 01/01/2023]
Abstract
The Mre11 nuclease has been the subject of intensive investigation for the past 20 years because of the central role that Mre11/Rad50 complexes play in genome maintenance. The last two decades of work on this complex has led to a much deeper understanding of the structure, biochemical activities, and regulation of Mre11/Rad50 complexes from archaea, bacteria, and eukaryotic cells. This review will discuss some of the important findings over recent years that have illuminated roles for the Mre11 nuclease in these different contexts as well as the insights from structural biology that have helped us to understand its mechanisms of action.
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Affiliation(s)
- Tanya T Paull
- Howard Hughes Medical Institute; Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, The University of Texas at Austin, Austin, TX 78712, USA.
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32
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GC content elevates mutation and recombination rates in the yeast Saccharomyces cerevisiae. Proc Natl Acad Sci U S A 2018; 115:E7109-E7118. [PMID: 29987035 PMCID: PMC6064992 DOI: 10.1073/pnas.1807334115] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The chromosomes of many eukaryotes have regions of high GC content interspersed with regions of low GC content. In the yeast Saccharomyces cerevisiae, high-GC regions are often associated with high levels of meiotic recombination. In this study, we constructed URA3 genes that differ substantially in their base composition [URA3-AT (31% GC), URA3-WT (43% GC), and URA3-GC (63% GC)] but encode proteins with the same amino acid sequence. The strain with URA3-GC had an approximately sevenfold elevated rate of ura3 mutations compared with the strains with URA3-WT or URA3-AT About half of these mutations were single-base substitutions and were dependent on the error-prone DNA polymerase ζ. About 30% were deletions or duplications between short (5-10 base) direct repeats resulting from DNA polymerase slippage. The URA3-GC gene also had elevated rates of meiotic and mitotic recombination relative to the URA3-AT or URA3-WT genes. Thus, base composition has a substantial effect on the basic parameters of genome stability and evolution.
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33
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Interdependent and separable functions of Caenorhabditis elegans MRN-C complex members couple formation and repair of meiotic DSBs. Proc Natl Acad Sci U S A 2018; 115:E4443-E4452. [PMID: 29686104 DOI: 10.1073/pnas.1719029115] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Faithful inheritance of genetic information through sexual reproduction relies on the formation of crossovers between homologous chromosomes during meiosis, which, in turn, relies on the formation and repair of numerous double-strand breaks (DSBs). As DSBs pose a potential threat to the genome, mechanisms that ensure timely and error-free DSB repair are crucial for successful meiosis. Here, we identify NBS-1, the Caenorhabditis elegans ortholog of the NBS1 (mutated in Nijmegen Breakage Syndrome) subunit of the conserved MRE11-RAD50-NBS1/Xrs2 (MRN) complex, as a key mediator of DSB repair via homologous recombination (HR) during meiosis. Loss of nbs-1 leads to severely reduced loading of recombinase RAD-51, ssDNA binding protein RPA, and pro-crossover factor COSA-1 during meiotic prophase progression; aggregated and fragmented chromosomes at the end of meiotic prophase; and 100% progeny lethality. These phenotypes reflect a role for NBS-1 in processing of meiotic DSBs for HR that is shared with its interacting partners MRE-11-RAD-50 and COM-1 (ortholog of Com1/Sae2/CtIP). Unexpectedly, in contrast to MRE-11 and RAD-50, NBS-1 is not required for meiotic DSB formation. Meiotic defects of the nbs-1 mutant are partially suppressed by abrogation of the nonhomologous end-joining (NHEJ) pathway, indicating a role for NBS-1 in antagonizing NHEJ during meiosis. Our data further reveal that NBS-1 and COM-1 play distinct roles in promoting HR and antagonizing NHEJ. We propose a model in which different components of the MRN-C complex work together to couple meiotic DSB formation with efficient and timely engagement of HR, thereby ensuring crossover formation and restoration of genome integrity before the meiotic divisions.
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34
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Poyedinok NL, Blume YB. Advances, Problems, and Prospects of Genetic Transformation of Fungi. CYTOL GENET+ 2018. [DOI: 10.3103/s009545271802007x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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35
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Ku DNA End-Binding Activity Promotes Repair Fidelity and Influences End-Processing During Nonhomologous End-Joining in Saccharomyces cerevisiae. Genetics 2018; 209:115-128. [PMID: 29500182 DOI: 10.1534/genetics.117.300672] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Accepted: 02/25/2018] [Indexed: 12/21/2022] Open
Abstract
The Ku heterodimer acts centrally in nonhomologous end-joining (NHEJ) of DNA double-strand breaks (DSB). Saccharomyces cerevisiae Ku, like mammalian Ku, binds and recruits NHEJ factors to DSB ends. Consequently, NHEJ is virtually absent in yeast Ku null (yku70∆ or yku80∆) strains. Previously, we unexpectedly observed imprecise NHEJ proficiency in a yeast Ku mutant with impaired DNA end-binding (DEB). However, how DEB impairment supported imprecise NHEJ was unknown. Here, we found imprecise NHEJ proficiency to be a feature of a panel of DEB-impaired Ku mutants and that DEB impairment resulted in a deficiency in precise NHEJ. These results suggest that DEB-impaired Ku specifically promotes error-prone NHEJ. Epistasis analysis showed that classical NHEJ factors, as well as novel and previously characterized NHEJ-specific residues of Ku, are required for the distinct error-prone repair in a Ku DEB mutant. However, sequencing of repair junctions revealed that imprecise repair in Ku DEB mutants was almost exclusively characterized by small deletions, in contrast to the majority of insertions that define imprecise repair in wild-type strains. Notably, while sequencing indicated a lack of Pol4-dependent insertions at the site of repair, Pol2 exonuclease activity, which mediates small deletions in NHEJ, contributed to imprecise NHEJ in a Ku DEB mutant. The deletions were smaller than in Ku-independent microhomology-mediated end-joining (MMEJ) and were neither promoted by Mre11 nuclease activity nor Sae2 Thus, the quality of Ku's engagement at the DNA end influences end-processing during NHEJ and DEB impairment unmasks a Ku-dependent error-prone pathway of end-joining distinct from MMEJ.
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Abstract
The mechanistic understanding of how DNA double-strand breaks (DSB) are repaired is rapidly advancing in part due to the advent of inducible site-specific break model systems as well as the employment of next-generation sequencing (NGS) technologies to sequence repair junctions at high depth. Unfortunately, the sheer volume of data produced by these methods makes it difficult to analyze the structure of repair junctions manually or with other general-purpose software. Here, we describe methods to produce amplicon libraries of DSB repair junctions for sequencing, to map the sequencing reads, and then to use a robust, custom python script, Hi-FiBR, to analyze the sequence structure of mapped reads. The Hi-FiBR analysis processes large data sets quickly and provides information such as number and type of repair events, size of deletion, size of insertion and inserted sequence, microhomology usage, and whether mismatches are due to sequencing error or biological effect. The analysis also corrects for common alignment errors generated by sequencing read mapping tools, allowing high-throughput analysis of DSB break repair fidelity to be accurately conducted regardless of which suite of NGS analysis software is available.
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Khodaverdian VY, Hanscom T, Yu AM, Yu TL, Mak V, Brown AJ, Roberts SA, McVey M. Secondary structure forming sequences drive SD-MMEJ repair of DNA double-strand breaks. Nucleic Acids Res 2018; 45:12848-12861. [PMID: 29121353 PMCID: PMC5728401 DOI: 10.1093/nar/gkx1056] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 10/18/2017] [Indexed: 12/29/2022] Open
Abstract
Alternative end-joining (alt-EJ) repair of DNA double-strand breaks is associated with deletions, chromosome translocations, and genome instability. Alt-EJ frequently uses annealing of microhomologous sequences to tether broken ends. When accessible pre-existing microhomologies do not exist, we have postulated that new microhomologies can be created via limited DNA synthesis at secondary-structure forming sequences. This model, called synthesis-dependent microhomology-mediated end joining (SD-MMEJ), predicts that differences between DNA sequences near double-strand breaks should alter repair outcomes in predictable ways. To test this hypothesis, we injected plasmids with sequence variations flanking an I-SceI endonuclease recognition site into I-SceI expressing Drosophila embryos and used Illumina amplicon sequencing to compare repair junctions. As predicted by the model, we found that small changes in sequences near the I-SceI site had major impacts on the spectrum of repair junctions. Bioinformatic analyses suggest that these repair differences arise from transiently forming loops and hairpins within 30 nucleotides of the break. We also obtained evidence for ‘trans SD-MMEJ,’ involving at least two consecutive rounds of microhomology annealing and synthesis across the break site. These results highlight the importance of sequence context for alt-EJ repair and have important implications for genome editing and genome evolution.
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Affiliation(s)
- Varandt Y Khodaverdian
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
| | - Terrence Hanscom
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
| | - Amy Marie Yu
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
| | - Taylor L Yu
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
| | - Victoria Mak
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
| | - Alexander J Brown
- School of Molecular Biosciences, Washington State University, P100 Dairy Road, Pullman, WA 99164, USA
| | - Steven A Roberts
- School of Molecular Biosciences, Washington State University, P100 Dairy Road, Pullman, WA 99164, USA
| | - Mitch McVey
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA 02155, USA
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38
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Omidi K, Jessulat M, Hooshyar M, Burnside D, Schoenrock A, Kazmirchuk T, Hajikarimlou M, Daniel M, Moteshareie H, Bhojoo U, Sanders M, Ramotar D, Dehne F, Samanfar B, Babu M, Golshani A. Uncharacterized ORF HUR1 influences the efficiency of non-homologous end-joining repair in Saccharomyces cerevisiae. Gene 2018; 639:128-136. [DOI: 10.1016/j.gene.2017.10.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 06/25/2017] [Accepted: 10/02/2017] [Indexed: 01/05/2023]
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39
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Genetic Separation of Sae2 Nuclease Activity from Mre11 Nuclease Functions in Budding Yeast. Mol Cell Biol 2017; 37:MCB.00156-17. [PMID: 28970327 DOI: 10.1128/mcb.00156-17] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2017] [Accepted: 09/25/2017] [Indexed: 02/01/2023] Open
Abstract
Sae2 promotes the repair of DNA double-strand breaks in Saccharomyces cerevisiae The role of Sae2 is linked to the Mre11/Rad50/Xrs2 (MRX) complex, which is important for the processing of DNA ends into single-stranded substrates for homologous recombination. Sae2 has intrinsic endonuclease activity, but the role of this activity has not been assessed independently from its functions in promoting Mre11 nuclease activity. Here we identify and characterize separation-of-function mutants that lack intrinsic nuclease activity or the ability to promote Mre11 endonucleolytic activity. We find that the ability of Sae2 to promote MRX nuclease functions is important for DNA damage survival, particularly in the absence of Dna2 nuclease activity. In contrast, Sae2 nuclease activity is essential for DNA repair when the Mre11 nuclease is compromised. Resection of DNA breaks is impaired when either Sae2 activity is blocked, suggesting roles for both Mre11 and Sae2 nuclease activities in promoting the processing of DNA ends in vivo Finally, both activities of Sae2 are important for sporulation, indicating that the processing of meiotic breaks requires both Mre11 and Sae2 nuclease activities.
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40
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Han J, Ruan C, Huen MSY, Wang J, Xie A, Fu C, Liu T, Huang J. BRCA2 antagonizes classical and alternative nonhomologous end-joining to prevent gross genomic instability. Nat Commun 2017; 8:1470. [PMID: 29133916 PMCID: PMC5684403 DOI: 10.1038/s41467-017-01759-y] [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: 07/06/2017] [Accepted: 10/13/2017] [Indexed: 12/27/2022] Open
Abstract
BRCA2-deficient cells exhibit gross genomic instability, but the underlying mechanisms are not fully understood. Here we report that inactivation of BRCA2 but not RAD51 destabilizes RPA-coated single-stranded DNA (ssDNA) structures at resected DNA double-strand breaks (DSBs) and greatly enhances the frequency of nuclear fragmentation following cell exposure to DNA damage. Importantly, these BRCA2-associated deficits are fueled by the aberrant activation of classical (c)- and alternative (alt)- nonhomologous end-joining (NHEJ), and rely on the well-defined DNA damage signaling pathway involving the pro-c-NHEJ factor 53BP1 and its downstream effector RIF1. We further show that the 53BP1–RIF1 axis promotes toxic end-joining events via the retention of Artemis at DNA damage sites. Accordingly, loss of 53BP1, RIF1, or Artemis prolongs the stability of RPA-coated DSB intermediates in BRCA2-deficient cells and restores nuclear integrity. We propose that BRCA2 antagonizes 53BP1, RIF1, and Artemis-dependent c-NHEJ and alt-NHEJ to prevent gross genomic instability in a RAD51-independent manner. The genomic instability phenotype characteristic of BRCA2-deficient cells is not fully mechanistically understood. Here the authors show BRCA2 inactivation destabilizes RPA-coated single-stranded DNA and leads to toxic non homologous end-joining events.
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Affiliation(s)
- Jinhua Han
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Chunyan Ruan
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Michael S Y Huen
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pok Fu Lam, Hong Kong, China
| | - Jiadong Wang
- Institute of Systems Biomedicine, Department of Radiation Medicine, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Anyong Xie
- Institute of Translational Medicine, College of Medicine, Zhejiang University, Hangzhou, Zhejiang, 310058, China
| | - Chun Fu
- Department of Obstetrics and Gynecology, The Second Xiangya Hospital of Central South University, Changsha, Hunan, 410011, China
| | - Ting Liu
- Department of Cell Biology, Zhejiang University School of Medicine, Hangzhou, Zhejiang, 310058, China
| | - Jun Huang
- Life Sciences Institute and Innovation Center for Cell Signaling Network, Zhejiang University, Hangzhou, Zhejiang, 310058, China.
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Seol JH, Shim EY, Lee SE. Microhomology-mediated end joining: Good, bad and ugly. Mutat Res 2017; 809:81-87. [PMID: 28754468 DOI: 10.1016/j.mrfmmm.2017.07.002] [Citation(s) in RCA: 149] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 06/21/2017] [Accepted: 07/03/2017] [Indexed: 01/06/2023]
Abstract
DNA double-strand breaks (DSBs) are induced by a variety of genotoxic agents, including ionizing radiation and chemotherapy drugs for treating cancers. The elimination of DSBs proceeds via distinctive error-free and error-prone pathways. Repair by homologous recombination (HR) is largely error-free and mediated by RAD51/BRCA2 gene products. Classical non-homologous end joining (C-NHEJ) requires the Ku heterodimer and can efficiently rejoin breaks, with occasional loss or gain of DNA information. Recently, evidence has unveiled another DNA end-joining mechanism that is independent of recombination factors and Ku proteins, termed alternative non-homologous end joining (A-NHEJ). While A-NHEJ-mediated repair does not require homology, in a subtype of A-NHEJ, DSB breaks are sealed by microhomology (MH)-mediated base-pairing of DNA single strands, followed by nucleolytic trimming of DNA flaps, DNA gap filling, and DNA ligation, yielding products that are always associated with DNA deletion. This highly error-prone DSB repair pathway is termed microhomology-mediated end joining (MMEJ). Dissecting the mechanisms of MMEJ is of great interest because of its potential to destabilize the genome through gene deletions and chromosomal rearrangements in cells deficient in canonical repair pathways, including HR and C-NHEJ. In addition, evidence now suggests that MMEJ plays a physiological role in normal cells.
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Affiliation(s)
- Ja-Hwan Seol
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States
| | - Sang Eun Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States; Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, United States.
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McVey M, Khodaverdian VY, Meyer D, Cerqueira PG, Heyer WD. Eukaryotic DNA Polymerases in Homologous Recombination. Annu Rev Genet 2017; 50:393-421. [PMID: 27893960 DOI: 10.1146/annurev-genet-120215-035243] [Citation(s) in RCA: 103] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Homologous recombination (HR) is a central process to ensure genomic stability in somatic cells and during meiosis. HR-associated DNA synthesis determines in large part the fidelity of the process. A number of recent studies have demonstrated that DNA synthesis during HR is conservative, less processive, and more mutagenic than replicative DNA synthesis. In this review, we describe mechanistic features of DNA synthesis during different types of HR-mediated DNA repair, including synthesis-dependent strand annealing, break-induced replication, and meiotic recombination. We highlight recent findings from diverse eukaryotic organisms, including humans, that suggest both replicative and translesion DNA polymerases are involved in HR-associated DNA synthesis. Our focus is to integrate the emerging literature about DNA polymerase involvement during HR with the unique aspects of these repair mechanisms, including mutagenesis and template switching.
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Affiliation(s)
- Mitch McVey
- Department of Biology, Tufts University, Medford, Massachusetts 02155;
| | | | - Damon Meyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616; .,College of Health Sciences, California Northstate University, Rancho Cordova, California 95670
| | - Paula Gonçalves Cerqueira
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616;
| | - Wolf-Dietrich Heyer
- Department of Microbiology and Molecular Genetics, University of California, Davis, California 95616; .,Department of Molecular and Cellular Biology, University of California, Davis, California 95616
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Sinha S, Li F, Villarreal D, Shim JH, Yoon S, Myung K, Shim EY, Lee SE. Microhomology-mediated end joining induces hypermutagenesis at breakpoint junctions. PLoS Genet 2017; 13:e1006714. [PMID: 28419093 PMCID: PMC5413072 DOI: 10.1371/journal.pgen.1006714] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 05/02/2017] [Accepted: 03/24/2017] [Indexed: 01/12/2023] Open
Abstract
Microhomology (MH) flanking a DNA double-strand break (DSB) drives chromosomal rearrangements but its role in mutagenesis has not yet been analyzed. Here we determined the mutation frequency of a URA3 reporter gene placed at multiple locations distal to a DSB, which is flanked by different sizes (15-, 18-, or 203-bp) of direct repeat sequences for efficient repair in budding yeast. Induction of a DSB accumulates mutations in the reporter gene situated up to 14-kb distal to the 15-bp MH, but more modestly to those carrying 18- and 203-bp or no homology. Increased mutagenesis in MH-mediated end joining (MMEJ) appears coupled to its slower repair kinetics and the extensive resection occurring at flanking DNA. Chromosomal translocations via MMEJ also elevate mutagenesis of the flanking DNA sequences 7.1 kb distal to the breakpoint junction as compared to those without MH. The results suggest that MMEJ could destabilize genomes by triggering structural alterations and increasing mutation burden. Recurrent chromosome translocations juxtapose chromosomal fragments and alter expression of tumor suppressors or oncogenes at or near breakpoint junctions to develop distinct types of leukemias and childhood sarcomas. The prevalence of 2–20 bp of imperfect overlapping sequences (a.k.a. microhomology [MH]) at the breakpoint junctions suggests the type of repair events joining two chromosomal fragments and the formation of oncogenic chromosomal translocations. In this study, we discovered that MH-mediated end joining (MMEJ) operates with kinetics markedly slower than other repair options. The slower kinetics leads to extensive resection and drives hypermutagenesis at sequences flanking the break site. We also found that MH-mediated chromosomal translocations accumulate mutations at sequences up to several kilobases distal to the breakpoint junction as compared to those without MH. Our results revealed that MH contributes to genetic instability by facilitating chromosomal translocations and increasing mutational load at the sequences flanking the breakpoints.
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Affiliation(s)
- Supriya Sinha
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America
| | - Fuyang Li
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America
| | - Diana Villarreal
- Children's Hospital of San Antonio, Baylor College of Medicine, San Antonio, TX, United States of America
| | - Jae Hoon Shim
- Korea Institute of Radiological & Medical Sciences (KIRAMS), 75 Nowon-ro, Nowon-gu, Seoul, Republic of Korea
| | - Suhyeon Yoon
- Department of Biological Science, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44818, Republic of Korea
| | - Kyungjae Myung
- Center for Genomic Integrity, Institute for Basic Science, Ulsan 44818, Republic of Korea
- Department of Biological Science, School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44818, Republic of Korea
| | - Eun Yong Shim
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America
| | - Sang Eun Lee
- Department of Molecular Medicine, Institute of Biotechnology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America
- Department of Radiation Oncology, University of Texas Health Science Center at San Antonio, San Antonio, TX, United States of America
- * E-mail:
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Genetic and biochemical evidences reveal novel insights into the mechanism underlying Saccharomyces cerevisiae Sae2-mediated abrogation of DNA replication stress. J Biosci 2017; 41:615-641. [PMID: 27966484 DOI: 10.1007/s12038-016-9642-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
In Saccharomyces cerevisiae, the Mre11-Rad50-Xrs2 (MRX) protein complex plays pivotal roles in double-strand break (DSB) repair, replication stress and telomere length maintenance. Another protein linked to DSB repair is Sae2, which regulates MRX persistence at DSBs. However, very little is known about its role in DNA replication stress and repair. Here, we reveal a crucial role for Sae2 in DNA replication stress. We show that different mutant alleles of SAE2 cause hypersensitivity to genotoxic agents, and when combined with Δmre11 or nuclease-defective mre11 mutant alleles, the double mutants are considerably more sensitive suggesting that the sae2 mutations synergize with mre11 mutations. Biochemical studies demonstrate that Sae2 exists as a dimer in solution, associates preferentially with single-stranded and branched DNA structures, exhibits structure-specific endonuclease activity and cleaves these substrates from the 5' end. Furthermore, we show that the nuclease activity is indeed intrinsic to Sae2. Interestingly, sae2G270D protein possesses DNA-binding activity, but lacks detectable nuclease activity. Altogether, our data suggest a direct role for Sae2 nuclease activity in processing of the DNA structures that arise during replication and DNA damage and provide insights into the mechanism underlying Mre11-Sae2-mediated abrogation of replication stressrelated defects in S. cerevisiae.
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45
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Control of DNA end resection by yeast Hmo1p affects efficiency of DNA end-joining. DNA Repair (Amst) 2017; 53:15-23. [PMID: 28336179 DOI: 10.1016/j.dnarep.2017.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/03/2017] [Accepted: 03/07/2017] [Indexed: 11/20/2022]
Abstract
The primary pathways for DNA double strand break (DSB) repair are homologous recombination (HR) and non-homologous end-joining (NHEJ). The choice between HR and NHEJ is influenced by the extent of DNA end resection, as extensive resection is required for HR but repressive to NHEJ. Conversely, association of the DNA end-binding protein Ku, which is integral to classical NHEJ, inhibits resection. In absence of key NHEJ components, a third repair pathway is exposed; this alternative-end joining (A-EJ) is a highly error-prone process that uses micro-homologies at the breakpoints and is initiated by DNA end resection. In Saccharomyces cerevisiae, the high mobility group protein Hmo1p has been implicated in controlling DNA end resection, suggesting its potential role in repair pathway choice. Using a plasmid end-joining assay, we show here that absence of Hmo1p results in reduced repair efficiency and accuracy, indicating that Hmo1p promotes end-joining; this effect is only observed on DNA with protruding ends. Notably, inhibition of DNA end resection in an hmo1Δ strain restores repair efficiency to the levels observed in wild-type cells. In absence of Ku, HMO1 deletion also reduces repair efficiency further, while inhibition of resection restores repair efficiency to the levels observed in kuΔ. We suggest that Hmo1p functions to control DNA end resection, thereby preventing error-prone A-EJ repair and directing repairs towards classical NHEJ. The very low efficiency of DSB repair in kuΔhmo1Δ cells further suggests that excessive DNA resection is inhibitory for A-EJ.
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46
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Regulation of non-homologous end joining via post-translational modifications of components of the ligation step. Curr Genet 2016; 63:591-605. [PMID: 27915381 DOI: 10.1007/s00294-016-0670-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 11/25/2016] [Accepted: 11/26/2016] [Indexed: 12/29/2022]
Abstract
DNA double-strand breaks are the most serious type of DNA damage and non-homologous end joining (NHEJ) is an important pathway for their repair. In Saccharomyces cerevisiae, three complexes mediate the canonical NHEJ pathway, Ku (Ku70/Ku80), MRX (Mre11/Rad50/Xrs2) and DNA ligase IV (Dnl4/Lif1). Mammalian NHEJ is more complex, primarily as a consequence of the fact that more factors are involved in the process, and also because higher chromatin organization and more complex regulatory networks exist in mammals. In addition, a stronger interconnection between the NHEJ and DNA damage response (DDR) pathways seems to occur in mammals compared to yeast. DDR employs multiple post-translational modifications (PTMs) of the target proteins and mutual crosstalk among them to ensure highly efficient down-stream effects. Checkpoint-mediated phosphorylation is the best understood PTM that regulates DDR, although recently SUMOylation has also been shown to be involved. Both phosphorylation and SUMOylation affect components of NHEJ. In this review, we discuss a role of these two PTMs in regulation of NHEJ via targeting the components of the ligation step.
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47
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Wyatt DW, Feng W, Conlin MP, Yousefzadeh MJ, Roberts SA, Mieczkowski P, Wood RD, Gupta GP, Ramsden DA. Essential Roles for Polymerase θ-Mediated End Joining in the Repair of Chromosome Breaks. Mol Cell 2016; 63:662-673. [PMID: 27453047 PMCID: PMC4992412 DOI: 10.1016/j.molcel.2016.06.020] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/20/2016] [Accepted: 06/14/2016] [Indexed: 01/04/2023]
Abstract
DNA polymerase theta (Pol θ)-mediated end joining (TMEJ) has been implicated in the repair of chromosome breaks, but its cellular mechanism and role relative to canonical repair pathways are poorly understood. We show that it accounts for most repairs associated with microhomologies and is made efficient by coupling a microhomology search to removal of non-homologous tails and microhomology-primed synthesis across broken ends. In contrast to non-homologous end joining (NHEJ), TMEJ efficiently repairs end structures expected after aborted homology-directed repair (5' to 3' resected ends) or replication fork collapse. It typically does not compete with canonical repair pathways but, in NHEJ-deficient cells, is engaged more frequently and protects against translocation. Cell viability is also severely impaired upon combined deficiency in Pol θ and a factor that antagonizes end resection (Ku or 53BP1). TMEJ thus helps to sustain cell viability and genome stability by rescuing chromosome break repair when resection is misregulated or NHEJ is compromised.
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Affiliation(s)
- David W Wyatt
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Wanjuan Feng
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Michael P Conlin
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Matthew J Yousefzadeh
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX 78597, USA
| | - Steven A Roberts
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA
| | - Piotr Mieczkowski
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, TX 78597, USA
| | - Gaorav P Gupta
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Radiation Oncology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Dale A Ramsden
- Lineberger Comprehensive Cancer Center, Curriculum in Genetics and Molecular Biology, and Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA.
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48
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Abstract
DNA polymerase theta (pol θ) is encoded in the genomes of many eukaryotes, though not in fungi. Pol θ is encoded by the POLQ gene in mammalian cells. The C-terminal third of the protein is a family A DNA polymerase with additional insertion elements relative to prokaryotic homologs. The N-terminal third is a helicase-like domain with DNA-dependent ATPase activity. Pol θ is important in the repair of genomic double-strand breaks (DSBs) from many sources. These include breaks formed by ionizing radiation and topoisomerase inhibitors, breaks arising at stalled DNA replication forks, breaks introduced during diversification steps of the mammalian immune system, and DSB induced by CRISPR-Cas9. Pol θ participates in a route of DSB repair termed "alternative end-joining" (altEJ). AltEJ is independent of the DNA binding Ku protein complex and requires DNA end resection. Pol θ is able to mediate joining of two resected 3' ends harboring DNA sequence microhomology. "Signatures" of Pol θ action during altEJ are the frequent utilization of longer microhomologies, and the insertion of additional sequences at joining sites. The mechanism of end-joining employs the ability of Pol θ to tightly grasp a 3' terminus through unique contacts in the active site, allowing extension from minimally paired primers. Pol θ is involved in controlling the frequency of chromosome translocations and preserves genome integrity by limiting large deletions. It may also play a backup role in DNA base excision repair. POLQ is a member of a cluster of similarly upregulated genes that are strongly correlated with poor clinical outcome for breast cancer, ovarian cancer and other cancer types. Inhibition of pol θ is a compelling approach for combination therapy of radiosensitization.
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Affiliation(s)
- Richard D Wood
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA; Graduate School of Biomedical Sciences at Houston, USA.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave, Burlington, VT 05405, USA.
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Bhargava R, Onyango DO, Stark JM. Regulation of Single-Strand Annealing and its Role in Genome Maintenance. Trends Genet 2016; 32:566-575. [PMID: 27450436 DOI: 10.1016/j.tig.2016.06.007] [Citation(s) in RCA: 311] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 06/28/2016] [Accepted: 06/29/2016] [Indexed: 01/19/2023]
Abstract
Single-strand annealing (SSA) is a DNA double-strand break (DSB) repair pathway that uses homologous repeats to bridge DSB ends. SSA involving repeats that flank a single DSB causes a deletion rearrangement between the repeats, and hence is relatively mutagenic. Nevertheless, this pathway is conserved, in that SSA events have been found in several organisms. In this review, we describe the mechanism of SSA and its regulation, including the cellular conditions that may favor SSA versus other DSB repair events. We will also evaluate the potential contribution of SSA to cancer-associated genome rearrangements, and to DSB-induced gene targeting.
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Affiliation(s)
- Ragini Bhargava
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA, USA; Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - David O Onyango
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA, USA
| | - Jeremy M Stark
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of the City of Hope, Duarte, CA, USA; Irell and Manella Graduate School of Biological Sciences, Beckman Research Institute of the City of Hope, Duarte, CA, USA.
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50
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Tsai RYL. Balancing self-renewal against genome preservation in stem cells: How do they manage to have the cake and eat it too? Cell Mol Life Sci 2016; 73:1803-23. [PMID: 26886024 PMCID: PMC5040593 DOI: 10.1007/s00018-016-2152-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Revised: 01/18/2016] [Accepted: 01/28/2016] [Indexed: 01/22/2023]
Abstract
Stem cells are endowed with the awesome power of self-renewal and multi-lineage differentiation that allows them to be major contributors to tissue homeostasis. Owing to their longevity and self-renewal capacity, they are also faced with a higher risk of genomic damage compared to differentiated cells. Damage on the genome, if not prevented or repaired properly, will threaten the survival of stem cells and culminate in organ failure, premature aging, or cancer formation. It is therefore of paramount importance that stem cells remain genomically stable throughout life. Given their unique biological and functional requirement, stem cells are thought to manage genotoxic stress somewhat differently from non-stem cells. The focus of this article is to review the current knowledge on how stem cells escape the barrage of oxidative and replicative DNA damage to stay in self-renewal. A clear statement on this subject should help us better understand tissue regeneration, aging, and cancer.
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Affiliation(s)
- Robert Y L Tsai
- Center for Translational Cancer Research, Institute of Biosciences and Technology, Texas A&M University Health Science Center, 2121 W. Holcombe Blvd, Houston, TX, 77030, USA.
- Department of Molecular and Cellular Medicine, Texas A&M University Health Science Center, College Station, TX, 77843, USA.
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