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Merker L, Feller L, Dorn A, Puchta H. Deficiency of both classical and alternative end-joining pathways leads to a synergistic defect in double-strand break repair but not to an increase in homology-dependent gene targeting in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2024; 118:242-254. [PMID: 38179887 DOI: 10.1111/tpj.16604] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 10/13/2023] [Accepted: 12/12/2023] [Indexed: 01/06/2024]
Abstract
In eukaryotes, double-strand breaks (DSBs) are either repaired by homologous recombination (HR) or non-homologous end-joining (NHEJ). In somatic plant cells, HR is very inefficient. Therefore, the vast majority of DSBs are repaired by two different pathways of NHEJ. The classical (cNHEJ) pathway depends on the heterodimer KU70/KU80, while polymerase theta (POLQ) is central to the alternative (aNHEJ) pathway. Surprisingly, Arabidopsis plants are viable, even when both pathways are impaired. However, they exhibit severe growth retardation and reduced fertility. Analysis of mitotic anaphases indicates that the double mutant is characterized by a dramatic increase in chromosome fragmentation due to defective DSB repair. In contrast to the single mutants, the double mutant was found to be highly sensitive to the DSB-inducing genotoxin bleomycin. Thus, both pathways can complement for each other efficiently in DSB repair. We speculated that in the absence of both NHEJ pathways, HR might be enhanced. This would be especially attractive for gene targeting (GT) in which predefined changes are introduced using a homologous template. Unexpectedly, the polq single mutant as well as the double mutant showed significantly lower GT frequencies in comparison to wildtype plants. Accordingly, we were able to show that elimination of both NHEJ pathways does not pose an attractive approach for Agrobacterium-mediated GT. However, our results clearly indicate that a loss of cNHEJ leads to an increase in GT frequency, which is especially drastic and attractive for practical applications, in which the in planta GT strategy is used.
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Affiliation(s)
- Laura Merker
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Laura Feller
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Annika Dorn
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
| | - Holger Puchta
- Joseph Gottlieb Kölreuter Institute for Plant Sciences, Karlsruhe Institute of Technology, Fritz-Haber-Weg 4, Karlsruhe, 76131, Germany
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2
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Lim PX, Zaman M, Feng W, Jasin M. BRCA2 promotes genomic integrity and therapy resistance primarily through its role in homology-directed repair. Mol Cell 2024; 84:447-462.e10. [PMID: 38244544 PMCID: PMC11188060 DOI: 10.1016/j.molcel.2023.12.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 10/10/2023] [Accepted: 12/15/2023] [Indexed: 01/22/2024]
Abstract
Tumor suppressor BRCA2 functions in homology-directed repair (HDR), the protection of stalled replication forks, and the suppression of replicative gaps, but their relative contributions to genome integrity and chemotherapy response are under scrutiny. Here, we report that mouse and human cells require a RAD51 filament stabilization motif in BRCA2 for fork protection and gap suppression but not HDR. In mice, the loss of fork protection/gap suppression does not compromise genome stability or shorten tumor latency. By contrast, HDR deficiency increases spontaneous and replication stress-induced chromosome aberrations and tumor predisposition. Unlike with HDR, fork protection/gap suppression defects are also observed in Brca2 heterozygous cells, likely due to reduced RAD51 stabilization at stalled forks/gaps. Gaps arise from PRIMPOL activity, which is associated with 5-hydroxymethyl-2'-deoxyuridine sensitivity due to the formation of SMUG1-generated abasic sites and is exacerbated by poly(ADP-ribose) polymerase (PARP) inhibition. However, HDR proficiency has the major role in mitigating sensitivity to chemotherapeutics, including PARP inhibitors.
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Affiliation(s)
- Pei Xin Lim
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Mahdia Zaman
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Weiran Feng
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA
| | - Maria Jasin
- Developmental Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA; Louis V. Gerstner Jr. Graduate School of Biomedical Sciences, Memorial Sloan Kettering Cancer Center, New York, NY, 10065, USA.
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3
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van Vugt MATM, Tijsterman M. POLQ to the rescue for double-strand break repair during mitosis. Nat Struct Mol Biol 2023; 30:1828-1830. [PMID: 37996664 DOI: 10.1038/s41594-023-01168-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Affiliation(s)
- Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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4
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Rogers CB, Kram RE, Lin K, Myers CL, Sobeck A, Hendrickson EA, Bielinsky AK. Fanconi anemia-associated chromosomal radial formation is dependent on POLθ-mediated alternative end joining. Cell Rep 2023; 42:112428. [PMID: 37086407 DOI: 10.1016/j.celrep.2023.112428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 01/25/2023] [Accepted: 04/07/2023] [Indexed: 04/23/2023] Open
Abstract
Activation of the Fanconi anemia (FA) pathway after treatment with mitomycin C (MMC) is essential for preventing chromosome translocations termed "radials." When replication forks stall at MMC-induced interstrand crosslinks (ICLs), the FA pathway is activated to orchestrate ICL unhooking and repair of the DNA break intermediates. However, in FA-deficient cells, how ICL-associated breaks are resolved in a manner that leads to radials is unclear. Here, we demonstrate that MMC-induced radials are dependent on DNA polymerase theta (POLθ)-mediated alternative end joining (A-EJ). Specifically, we show that radials observed in FANCD2-/- cells are dependent on POLθ and DNA ligase III and occur independently of classical non-homologous end joining. Furthermore, treatment of FANCD2-/- cells with POLθ inhibitors abolishes radials and leads to the accumulation of breaks co-localizing with common fragile sites. Uniformly, these observations implicate A-EJ in radial formation and provide mechanistic insights into the treatment of FA pathway-deficient cancers with POLθ inhibitors.
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Affiliation(s)
- Colette B Rogers
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Rachel E Kram
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kevin Lin
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Chad L Myers
- Department of Computer Science and Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alexandra Sobeck
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Anja-Katrin Bielinsky
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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5
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Lim PX, Zaman M, Jasin M. BRCA2 promotes genomic integrity and therapy resistance primarily through its role in homology-directed repair. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.11.536470. [PMID: 37090587 PMCID: PMC10120702 DOI: 10.1101/2023.04.11.536470] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Highlights Gap suppression requires BRCA2 C-terminal RAD51 binding in mouse and human cells Brca2 heterozygosity in mice results in fork protection and gap suppression defects Gap suppression mitigates sensitivity to hmdU, but only when HDR is unperturbedHDR deficiency is the primary driver of chemotherapeutic sensitivity. eTOC blurb Lim et al . report that gap suppression as well as fork protection require BRCA2 stabilization of RAD51 filaments in human and mouse cells but have minimal impact on genome integrity, oncogenesis, and drug resistance. BRCA2 suppression of PRIMPOL-mediated replication gaps confers resistance to the nucleotide hmdU, incorporation of which leads to cytotoxic abasic sites.This effect is diminished when HDR is abrogated. Summary Tumor suppressor BRCA2 functions in homology-directed repair (HDR), protection of stalled replication forks, and suppression of replicative gaps. The relative contributions of these pathways to genome integrity and chemotherapy response are under scrutiny. Here, we report that mouse and human cells require a RAD51 filament stabilization motif in BRCA2 for both fork protection and gap suppression, but not HDR. Loss of fork protection and gap suppression do not compromise genome instability or shorten tumor latency in mice or cause replication stress in human mammary cells. By contrast, HDR deficiency increases spontaneous and replication stress-induced chromosome aberrations and tumor predisposition. Unlike with HDR, fork protection and gap suppression defects are also observed in Brca2 heterozygous mouse cells, likely due to reduced RAD51 stabilization at stalled forks and gaps. Gaps arise from PRIMPOL activity, which is associated with sensitivity to 5-hydroxymethyl-2’-deoxyuridine due to the formation of abasic sites by SMUG1 glycosylase and is exacerbated by poly(ADP-ribose) polymerase inhibition. However, HDR deficiency ultimately modulates sensitivity to chemotherapeutics, including PARP inhibitors.
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6
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Patterson-Fortin J, Jadhav H, Pantelidou C, Phan T, Grochala C, Mehta AK, Guerriero JL, Wulf GM, Wolpin BM, Stanger BZ, Aguirre AJ, Cleary JM, D'Andrea AD, Shapiro GI. Polymerase θ inhibition activates the cGAS-STING pathway and cooperates with immune checkpoint blockade in models of BRCA-deficient cancer. Nat Commun 2023; 14:1390. [PMID: 36914658 PMCID: PMC10011609 DOI: 10.1038/s41467-023-37096-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/02/2023] [Indexed: 03/16/2023] Open
Abstract
Recently developed inhibitors of polymerase theta (POLθ) have demonstrated synthetic lethality in BRCA-deficient tumor models. To examine the contribution of the immune microenvironment to antitumor efficacy, we characterized the effects of POLθ inhibition in immunocompetent models of BRCA1-deficient triple-negative breast cancer (TNBC) or BRCA2-deficient pancreatic ductal adenocarcinoma (PDAC). We demonstrate that genetic POLQ depletion or pharmacological POLθ inhibition induces both innate and adaptive immune responses in these models. POLθ inhibition resulted in increased micronuclei, cGAS/STING pathway activation, type I interferon gene expression, CD8+ T cell infiltration and activation, local paracrine activation of dendritic cells and upregulation of PD-L1 expression. Depletion of CD8+ T cells compromised the efficacy of POLθ inhibition, whereas antitumor effects were augmented in combination with anti-PD-1 immunotherapy. Collectively, our findings demonstrate that POLθ inhibition induces immune responses in a cGAS/STING-dependent manner and provide a rationale for combining POLθ inhibition with immune checkpoint blockade for the treatment of HR-deficient cancers.
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Affiliation(s)
- Jeffrey Patterson-Fortin
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA
| | - Heta Jadhav
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Constantia Pantelidou
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Bayer Pharmaceuticals, Cambridge, MA, USA
| | - Tin Phan
- Department of Radiation Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, 02215, USA
| | - Carter Grochala
- Department of Radiation Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, 02215, USA
- Arpeggio, Boulder, CO, USA
| | - Anita K Mehta
- Department of Surgical Oncology and Harvard Medical School, Brigham and Women's Hospital, Boston, MA, 02115, USA
- Sanofi, Cambridge, MA, USA
| | - Jennifer L Guerriero
- Department of Surgical Oncology and Harvard Medical School, Brigham and Women's Hospital, Boston, MA, 02115, USA
| | - Gerburg M Wulf
- Department of Medicine, Division of Hematology-Oncology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, 02215, USA
| | - Brian M Wolpin
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA
- Hale Family Center for Pancreatic Cancer Research, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Ben Z Stanger
- Department of Medicine, Division of Gastroenterology, Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, 19104, USA
| | - Andrew J Aguirre
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA
- Hale Family Center for Pancreatic Cancer Research, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - James M Cleary
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA
- Hale Family Center for Pancreatic Cancer Research, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute and Harvard Medical School, Boston, MA, 02215, USA
- Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Geoffrey I Shapiro
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
- Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, 02115, USA.
- Center for DNA Damage and Repair, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
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7
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Patterson-Fortin J, D'Andrea AD. Targeting Polymerase Theta (POLθ) for Cancer Therapy. Cancer Treat Res 2023; 186:285-298. [PMID: 37978141 DOI: 10.1007/978-3-031-30065-3_15] [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: 11/19/2023]
Abstract
Polymerase theta (POLθ) is the critical multi-domain enzyme in microhomology-mediated end-joining DNA double-stranded break repair. POLθ is expressed at low levels in normal tissue but is often overexpressed in cancers, especially in DNA repair deficient cancers, such as homologous-recombination cancers, rendering them exquisitely sensitive to POLθ inhibition secondary to synthetic lethality. Development of POLθ inhibitors is an active area of investigation with inhibitors of the N-terminal helicase domain or the C-terminal polymerase domain currently in clinical trial. Here, we review POLθ-mediated microhomology-mediated end-joining, the development of POLθ inhibitors, and the potential clinical uses of POLθ inhibitors.
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Affiliation(s)
- Jeffrey Patterson-Fortin
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA
| | - Alan D D'Andrea
- Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
- Harvard Medical School, Center for DNA Damage and Repair, Susan F. Smith Center for Women's Cancers (SFSCWC), The Fuller-American Cancer Society, Dana-Farber Cancer Institute, HIM 243, 450 Brookline Ave., Boston, MA, 02215, USA.
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8
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Zhao S, Goewey Ruiz JA, Sebastian M, Kidane D. Defective DNA polymerase beta invoke a cytosolic DNA mediated inflammatory response. Front Immunol 2022; 13:1039009. [PMID: 36624848 PMCID: PMC9823925 DOI: 10.3389/fimmu.2022.1039009] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 12/05/2022] [Indexed: 12/24/2022] Open
Abstract
Base excision repair (BER) has evolved to maintain the genomic integrity of DNA following endogenous and exogenous agent induced DNA base damage. In contrast, aberrant BER induces genomic instability, promotes malignant transformation and can even trigger cancer development. Previously, we have shown that deoxyribo-5'-phosphate (dRP) lyase deficient DNA polymerase beta (POLB) causes replication associated genomic instability and sensitivity to both endogenous and exogenous DNA damaging agents. Specifically, it has been established that this loss of dRP lyase function promotes inflammation associated gastric cancer. However, the way that aberrant POLB impacts the immune signaling and inflammatory responses is still unknown. Here we show that a dRP lyase deficient variant of POLB (Leu22Pro, or L22P) increases mitotic dysfunction associated genomic instability, which eventually leads to a cytosolic DNA mediated inflammatory response. Furthermore, poly(ADP-ribose) polymerase 1 inhibition exacerbates chromosomal instability and enhances the cytosolic DNA mediated inflammatory response. Our results suggest that POLB plays a significant role in modulating inflammatory signaling, and they provide a mechanistic basis for future potential cancer immunotherapies.
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Affiliation(s)
- Shengyuan Zhao
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, TX, United States
| | - Julia A. Goewey Ruiz
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, TX, United States
| | - Manu Sebastian
- Dept. of Veterinary Medicine & Surgery, University of Texas (UT) MD Anderson Cancer Center, Houston, TX, United States
- Dept. of Translational Molecular Pathology, University of Texas (UT) MD Anderson Cancer Center, Houston, TX, United States
| | - Dawit Kidane
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Dell Pediatric Research Institute, Austin, TX, United States
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Abstract
DNA polymerase θ (Pol θ) is a DNA repair enzyme widely conserved in animals and plants. Pol θ uses short DNA sequence homologies to initiate repair of double-strand breaks by theta-mediated end joining. The DNA polymerase domain of Pol θ is at the C terminus and is connected to an N-terminal DNA helicase-like domain by a central linker. Pol θ is crucial for maintenance of damaged genomes during development, protects DNA against extensive deletions, and limits loss of heterozygosity. The cost of using Pol θ for genome protection is that a few nucleotides are usually deleted or added at the repair site. Inactivation of Pol θ often enhances the sensitivity of cells to DNA strand-breaking chemicals and radiation. Since some homologous recombination-defective cancers depend on Pol θ for growth, inhibitors of Pol θ may be useful in treating such tumors.
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Affiliation(s)
- Richard D Wood
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Center, Houston, Texas, USA;
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA;
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10
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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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11
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Drzewiecka M, Barszczewska-Pietraszek G, Czarny P, Skorski T, Śliwiński T. Synthetic Lethality Targeting Polθ. Genes (Basel) 2022; 13:genes13061101. [PMID: 35741863 PMCID: PMC9223150 DOI: 10.3390/genes13061101] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 06/06/2022] [Accepted: 06/11/2022] [Indexed: 01/27/2023] Open
Abstract
Research studies regarding synthetic lethality (SL) in human cells are primarily motivated by the potential of this phenomenon to be an effective, but at the same time, safe to the patient's anti-cancer chemotherapy. Among the factors that are targets for the induction of the synthetic lethality effect, those involved in DNA repair seem to be the most relevant. Specifically, when mutation in one of the canonical DNA double-strand break (DSB) repair pathways occurs, which is a frequent event in cancer cells, the alternative pathways may be a promising target for the elimination of abnormal cells. Currently, inhibiting RAD52 and/or PARP1 in the tumor cells that are deficient in the canonical repair pathways has been the potential target for inducing the effect of synthetic lethality. Unfortunately, the development of resistance to commonly used PARP1 inhibitors (PARPi) represents the greatest obstacle to working out a successful treatment protocol. DNA polymerase theta (Polθ), encoded by the POLQ gene, plays a key role in an alternative DSB repair pathway-theta-mediated end joining (TMEJ). Thus, it is a promising target in the treatment of tumors harboring deficiencies in homologous recombination repair (HRR), where its inhibition can induce SL. In this review, the authors discuss the current state of knowledge on Polθ as a potential target for synthetic lethality-based anticancer therapies.
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Affiliation(s)
- Małgorzata Drzewiecka
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland; (M.D.); (G.B.-P.)
| | - Gabriela Barszczewska-Pietraszek
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland; (M.D.); (G.B.-P.)
| | - Piotr Czarny
- Department of Medical Biochemistry, Medical University of Lodz, 92-216 Lodz, Poland;
| | - Tomasz Skorski
- Fels Cancer Institute for Personalized Medicine, Departament of Cancer and Cellular Biology, Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
- Correspondence: (T.S.); (T.Ś.); Tel.: +1-215-707-9157 (T.S.); +48-42-635-44-86 (T.Ś.)
| | - Tomasz Śliwiński
- Laboratory of Medical Genetics, Faculty of Biology and Environmental Protection, University of Lodz, 90-236 Lodz, Poland; (M.D.); (G.B.-P.)
- Correspondence: (T.S.); (T.Ś.); Tel.: +1-215-707-9157 (T.S.); +48-42-635-44-86 (T.Ś.)
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12
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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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13
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Zahn KE, Jensen RB, Wood RD, Doublié S. RETRACTED: Human DNA polymerase θ harbors DNA end-trimming activity critical for DNA repair. Mol Cell 2021; 81:1534-1547.e4. [PMID: 33577776 PMCID: PMC8231307 DOI: 10.1016/j.molcel.2021.01.021] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 11/24/2020] [Accepted: 01/15/2021] [Indexed: 12/12/2022]
Abstract
Cancers with hereditary defects in homologous recombination rely on DNA polymerase θ (pol θ) for repair of DNA double-strand breaks. During end joining, pol θ aligns microhomology tracts internal to 5'-resected broken ends. An unidentified nuclease trims the 3' ends before synthesis can occur. Here we report that a nuclease activity, which differs from the proofreading activity often associated with DNA polymerases, is intrinsic to the polymerase domain of pol θ. Like the DNA synthesis activity, the nuclease activity requires conserved metal-binding residues, metal ions, and dNTPs and is inhibited by ddNTPs or chain-terminated DNA. Our data indicate that pol θ repurposes metal ions in the polymerase active site for endonucleolytic cleavage and that the polymerase-active and end-trimming conformations of the enzyme are distinct. We reveal a nimble strategy of substrate processing that allows pol θ to trim or extend DNA depending on the DNA repair context.
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Affiliation(s)
- Karl E Zahn
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA; Department of Therapeutic Radiology, Yale University, New Haven, CT 06510, USA
| | - Ryan B Jensen
- Department of Therapeutic Radiology, Yale University, New Haven, CT 06510, USA
| | - Richard D Wood
- Department of Epigenetics & Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 78957, USA.
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, 89 Beaumont Ave., Burlington, VT 05405, USA.
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Jilderda LJ, Zhou L, Foijer F. Understanding How Genetic Mutations Collaborate with Genomic Instability in Cancer. Cells 2021; 10:342. [PMID: 33562057 PMCID: PMC7914657 DOI: 10.3390/cells10020342] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2020] [Revised: 01/25/2021] [Accepted: 02/03/2021] [Indexed: 01/23/2023] Open
Abstract
Chromosomal instability is the process of mis-segregation for ongoing chromosomes, which leads to cells with an abnormal number of chromosomes, also known as an aneuploid state. Induced aneuploidy is detrimental during development and in primary cells but aneuploidy is also a hallmark of cancer cells. It is therefore believed that premalignant cells need to overcome aneuploidy-imposed stresses to become tumorigenic. Over the past decade, some aneuploidy-tolerating pathways have been identified through small-scale screens, which suggest that aneuploidy tolerance pathways can potentially be therapeutically exploited. However, to better understand the processes that lead to aneuploidy tolerance in cancer cells, large-scale and unbiased genetic screens are needed, both in euploid and aneuploid cancer models. In this review, we describe some of the currently known aneuploidy-tolerating hits, how large-scale genome-wide screens can broaden our knowledge on aneuploidy specific cancer driver genes, and how we can exploit the outcomes of these screens to improve future cancer therapy.
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Affiliation(s)
| | | | - Floris Foijer
- European Research Institute for the Biology of Ageing (ERIBA), University of Groningen, University Medical Centre Groningen, 9713 AV Groningen, The Netherlands; (L.J.J.); (L.Z.)
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15
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Schimmel J, van Schendel R, den Dunnen JT, Tijsterman M. Templated Insertions: A Smoking Gun for Polymerase Theta-Mediated End Joining. Trends Genet 2019; 35:632-644. [PMID: 31296341 DOI: 10.1016/j.tig.2019.06.001] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2019] [Revised: 05/27/2019] [Accepted: 06/06/2019] [Indexed: 01/23/2023]
Abstract
A recognized source of disease-causing genome alterations is erroneous repair of broken chromosomes, which can be executed by two distinct mechanisms: non-homologous end joining (NHEJ) and the recently discovered polymerase theta-mediated end joining (TMEJ) pathway. While TMEJ has previously been considered to act as an alternative mechanism backing up NHEJ, recent work points to a role for TMEJ in the repair of replication-associated DNA breaks that are excluded from repair through homologous recombination. Because of its mode of action, TMEJ is intrinsically mutagenic and sometimes leaves behind a recognizable genomic scar when joining chromosome break ends (i.e., 'templated insertions'). This review article focuses on the intriguing observation that this polymerase theta signature is frequently observed in disease alleles, arguing for a prominent role of this double-strand break repair pathway in genome diversification and disease-causing spontaneous mutagenesis in humans.
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Affiliation(s)
- Joost Schimmel
- Department of Human Genetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Johan T den Dunnen
- Department of Human Genetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
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16
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Wang Z, Song Y, Li S, Kurian S, Xiang R, Chiba T, Wu X. DNA polymerase θ (POLQ) is important for repair of DNA double-strand breaks caused by fork collapse. J Biol Chem 2019; 294:3909-3919. [PMID: 30655289 PMCID: PMC6422074 DOI: 10.1074/jbc.ra118.005188] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2018] [Revised: 01/05/2019] [Indexed: 12/31/2022] Open
Abstract
DNA polymerase θ (POLQ) plays an important role in alternative nonhomologous end joining or microhomology-mediated end joining (alt-NHEJ/MMEJ). Here, we show that POLQ is not only required for MMEJ to repair DNA double-strand breaks (DSBs) generated by endonucleases such as I-SceI or Cas9, but is also needed for repair of DSBs derived from DNA nicks generated by Cas9 nickase. Consistently, we found that POLQ deficiency leads to sensitivity to topoisomerase inhibitors that cause DNA single-strand break (SSB) accumulation at replication forks and to ATR inhibitors that induce replication fork collapse. These studies support the function of POLQ in coping with replication stress and repairing DSBs upon fork collapse. POLQ overexpression is present in many cancer types and is associated with poor prognosis, including breast cancer regardless of BRCA1 status. We provide proof-of-concept evidence to support a novel cancer treatment strategy that combines POLQ inhibition with administration of topoisomerase or ATR inhibitors, which induces replication stress and fork collapse. Given the prevalence of POLQ overexpression in tumors, such strategy may have a significant impact on developing targeted cancer treatment.
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Affiliation(s)
- Zi Wang
- From the Department of Molecular Medicine, Scripps Research Institute, La Jolla, California 92037
- the Biomedical Gerontology Laboratory, Faculty of Human Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa 359-1192, Japan
| | - Yadong Song
- From the Department of Molecular Medicine, Scripps Research Institute, La Jolla, California 92037
- the School of Medicine, Nankai University, 94 Weijin Road, Tianjin 300071, China, and
| | - Shibo Li
- From the Department of Molecular Medicine, Scripps Research Institute, La Jolla, California 92037
| | - Sunil Kurian
- the Division of Organ Transplant, Scripps Health, La Jolla, California 92037
| | - Rong Xiang
- the School of Medicine, Nankai University, 94 Weijin Road, Tianjin 300071, China, and
| | - Takuya Chiba
- the Biomedical Gerontology Laboratory, Faculty of Human Sciences, Waseda University, 2-579-15 Mikajima, Tokorozawa 359-1192, Japan
| | - Xiaohua Wu
- From the Department of Molecular Medicine, Scripps Research Institute, La Jolla, California 92037,
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17
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Sakamoto AN. Translesion Synthesis in Plants: Ultraviolet Resistance and Beyond. FRONTIERS IN PLANT SCIENCE 2019; 10:1208. [PMID: 31649692 PMCID: PMC6794406 DOI: 10.3389/fpls.2019.01208] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 09/03/2019] [Indexed: 05/06/2023]
Abstract
Plant genomes sustain various forms of DNA damage that stall replication forks. Translesion synthesis (TLS) is one of the pathways to overcome stalled replication in which specific polymerases (TLS polymerase) perform bypass synthesis across DNA damage. This article gives a brief overview of plant TLS polymerases. In Arabidopsis, DNA polymerase (Pol) ζ, η, κ, θ, and λ and Reversionless1 (Rev1) are shown to be involved in the TLS. For example, AtPolη bypasses ultraviolet (UV)-induced cyclobutane pyrimidine dimers in vitro. Disruption of AtPolζ or AtPolη increases root stem cell death after UV irradiation. These results suggest that AtPolζ and ATPolη bypass UV-induced damage, prevent replication arrest, and allow damaged cells to survive and grow. In general, TLS polymerases have low fidelity and often induce mutations. Accordingly, disruption of AtPolζ or AtRev1 reduces somatic mutation frequency, whereas disruption of AtPolη elevates it, suggesting that plants have both mutagenic and less mutagenic TLS activities. The stalled replication fork can be resolved by a strand switch pathway involving a DNA helicase Rad5. Disruption of both AtPolζ and AtRAD5a shows synergistic or additive effects in the sensitivity to DNA-damaging agents. Moreover, AtPolζ or AtRev1 disruption elevates homologous recombination frequencies in somatic tissues. These results suggest that the Rad5-dependent pathway and TLS are parallel. Plants grown in the presence of heat shock protein 90 (HSP90) inhibitor showed lower mutation frequencies, suggesting that HSP90 regulates mutagenic TLS in plants. Hypersensitivities of TLS-deficient plants to γ-ray and/or crosslink damage suggest that plant TLS polymerases have multiple roles, as reported in other organisms.
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18
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Nébor D, Graber JH, Ciciotte SL, Robledo RF, Papoin J, Hartman E, Gillinder KR, Perkins AC, Bieker JJ, Blanc L, Peters LL. Mutant KLF1 in Adult Anemic Nan Mice Leads to Profound Transcriptome Changes and Disordered Erythropoiesis. Sci Rep 2018; 8:12793. [PMID: 30143664 PMCID: PMC6109071 DOI: 10.1038/s41598-018-30839-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/02/2018] [Indexed: 12/31/2022] Open
Abstract
Anemic Nan mice carry a mutation (E339D) in the second zinc finger of erythroid transcription factor KLF1. Nan-KLF1 fails to bind a subset of normal KLF1 targets and ectopically binds a large set of genes not normally engaged by KLF1, resulting in a corrupted fetal liver transcriptome. Here, we performed RNAseq using flow cytometric-sorted spleen erythroid precursors from adult Nan and WT littermates rendered anemic by phlebotomy to identify global transcriptome changes specific to the Nan Klf1 mutation as opposed to anemia generally. Mutant Nan-KLF1 leads to extensive and progressive transcriptome corruption in adult spleen erythroid precursors such that stress erythropoiesis is severely compromised. Terminal erythroid differentiation is defective in the bone marrow as well. Principle component analysis reveals two major patterns of differential gene expression predicting that defects in basic cellular processes including translation, cell cycle, and DNA repair could contribute to disordered erythropoiesis and anemia in Nan. Significant erythroid precursor stage specific changes were identified in some of these processes in Nan. Remarkably, however, despite expression changes in large numbers of associated genes, most basic cellular processes were intact in Nan indicating that developing red cells display significant physiological resiliency and establish new homeostatic set points in vivo.
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Affiliation(s)
| | - Joel H Graber
- The Jackson Laboratory, Bar Harbor, ME, 04609, USA.,MDI Biological Laboratory, Salisbury Cove, ME, 04672, USA
| | | | | | - Julien Papoin
- Feinstein Institute for Medical Research, Manhasset, NY, 11030, USA
| | - Emily Hartman
- Feinstein Institute for Medical Research, Manhasset, NY, 11030, USA
| | - Kevin R Gillinder
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, 3004, Australia.,The Alfred Hospital, Melbourne, VIC, 3004, Australia
| | - Andrew C Perkins
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC, 3004, Australia.,The Alfred Hospital, Melbourne, VIC, 3004, Australia
| | - James J Bieker
- Department of Cell, Developmental and Regenerative Biology, Mount Sinai School of Medicine, New York, NY, 10029, USA
| | - Lionel Blanc
- Feinstein Institute for Medical Research, Manhasset, NY, 11030, USA
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19
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Seo YS, Kang YH. The Human Replicative Helicase, the CMG Complex, as a Target for Anti-cancer Therapy. Front Mol Biosci 2018; 5:26. [PMID: 29651420 PMCID: PMC5885281 DOI: 10.3389/fmolb.2018.00026] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/12/2018] [Indexed: 12/14/2022] Open
Abstract
DNA helicases unwind or rearrange duplex DNA during replication, recombination and repair. Helicases of many pathogenic organisms such as viruses, bacteria, and protozoa have been studied as potential therapeutic targets to treat infectious diseases, and human DNA helicases as potential targets for anti-cancer therapy. DNA replication machineries perform essential tasks duplicating genome in every cell cycle, and one of the important functions of these machineries are played by DNA helicases. Replicative helicases are usually multi-subunit protein complexes, and the minimal complex active as eukaryotic replicative helicase is composed of 11 subunits, requiring a functional assembly of two subcomplexes and one protein. The hetero-hexameric MCM2-7 helicase is activated by forming a complex with Cdc45 and the hetero-tetrameric GINS complex; the Cdc45-Mcm2-7-GINS (CMG) complex. The CMG complex can be a potential target for a treatment of cancer and the feasibility of this replicative helicase as a therapeutic target has been tested recently. Several different strategies have been implemented and are under active investigations to interfere with helicase activity of the CMG complex. This review focuses on the molecular function of the CMG helicase during DNA replication and its relevance to cancers based on data published in the literature. In addition, current efforts made to identify small molecules inhibiting the CMG helicase to develop anti-cancer therapeutic strategies were summarized, with new perspectives to advance the discovery of the CMG-targeting drugs.
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Affiliation(s)
- Yeon-Soo Seo
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, South Korea
| | - Young-Hoon Kang
- Core Protein Resources Center, Daegu Gyeongbuk Institute of Science and Technology, Daegu, South Korea
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20
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Abstract
The number of DNA polymerases identified in each organism has mushroomed in the past two decades. Most newly found DNA polymerases specialize in translesion synthesis and DNA repair instead of replication. Although intrinsic error rates are higher for translesion and repair polymerases than for replicative polymerases, the specialized polymerases increase genome stability and reduce tumorigenesis. Reflecting the numerous types of DNA lesions and variations of broken DNA ends, translesion and repair polymerases differ in structure, mechanism, and function. Here, we review the unique and general features of polymerases specialized in lesion bypass, as well as in gap-filling and end-joining synthesis.
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Affiliation(s)
- Wei Yang
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA;
| | - Yang Gao
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA;
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21
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Quinet A, Lerner LK, Martins DJ, Menck CFM. Filling gaps in translesion DNA synthesis in human cells. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2018; 836:127-142. [PMID: 30442338 DOI: 10.1016/j.mrgentox.2018.02.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 02/21/2018] [Indexed: 01/06/2023]
Abstract
During DNA replication, forks may encounter unrepaired lesions that hamper DNA synthesis. Cells have universal strategies to promote damage bypass allowing cells to survive. DNA damage tolerance can be performed upon template switch or by specialized DNA polymerases, known as translesion (TLS) polymerases. Human cells count on more than eleven TLS polymerases and this work reviews the functions of some of these enzymes: Rev1, Pol η, Pol ι, Pol κ, Pol θ and Pol ζ. The mechanisms of damage bypass vary according to the lesion, as well as to the TLS polymerases available, and may occur directly at the fork during replication. Alternatively, the lesion may be skipped, leaving a single-stranded DNA gap that will be replicated later. Details of the participation of these enzymes are revised for the replication of damaged template. TLS polymerases also have functions in other cellular processes. These include involvement in somatic hypermutation in immunoglobulin genes, direct participation in recombination and repair processes, and contributing to replicating noncanonical DNA structures. The importance of DNA damage replication to cell survival is supported by recent discoveries that certain genes encoding TLS polymerases are induced in response to DNA damaging agents, protecting cells from a subsequent challenge to DNA replication. We retrace the findings on these genotoxic (adaptive) responses of human cells and show the common aspects with the SOS responses in bacteria. Paradoxically, although TLS of DNA damage is normally an error prone mechanism, in general it protects from carcinogenesis, as evidenced by increased tumorigenesis in xeroderma pigmentosum variant patients, who are deficient in Pol η. As these TLS polymerases also promote cell survival, they constitute an important mechanism by which cancer cells acquire resistance to genotoxic chemotherapy. Therefore, the TLS polymerases are new potential targets for improving therapy against tumors.
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Affiliation(s)
- Annabel Quinet
- Saint Louis University School of Medicine, St. Louis, MO, United States.
| | - Leticia K Lerner
- MRC Laboratory of Molecular Biology,Francis Crick Avenue, Cambridge CB2 0QH, UK.
| | - Davi J Martins
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Carlos F M Menck
- Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
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22
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Family A and B DNA Polymerases in Cancer: Opportunities for Therapeutic Interventions. BIOLOGY 2018; 7:biology7010005. [PMID: 29301327 PMCID: PMC5872031 DOI: 10.3390/biology7010005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/14/2017] [Accepted: 12/29/2017] [Indexed: 02/07/2023]
Abstract
DNA polymerases are essential for genome replication, DNA repair and translesion DNA synthesis (TLS). Broadly, these enzymes belong to two groups: replicative and non-replicative DNA polymerases. A considerable body of data suggests that both groups of DNA polymerases are associated with cancer. Many mutations in cancer cells are either the result of error-prone DNA synthesis by non-replicative polymerases, or the inability of replicative DNA polymerases to proofread mismatched nucleotides due to mutations in 3'-5' exonuclease activity. Moreover, non-replicative, TLS-capable DNA polymerases can negatively impact cancer treatment by synthesizing DNA past lesions generated from treatments such as cisplatin, oxaliplatin, etoposide, bleomycin, and radiotherapy. Hence, the inhibition of DNA polymerases in tumor cells has the potential to enhance treatment outcomes. Here, we review the association of DNA polymerases in cancer from the A and B families, which participate in lesion bypass, and conduct gene replication. We also discuss possible therapeutic interventions that could be used to maneuver the role of these enzymes in tumorigenesis.
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23
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Bournique E, Dall'Osto M, Hoffmann JS, Bergoglio V. Role of specialized DNA polymerases in the limitation of replicative stress and DNA damage transmission. Mutat Res 2017; 808:62-73. [PMID: 28843435 DOI: 10.1016/j.mrfmmm.2017.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 01/31/2023]
Abstract
Replication stress is a strong and early driving force for genomic instability and tumor development. Beside replicative DNA polymerases, an emerging group of specialized DNA polymerases is involved in the technical assistance of the replication machinery in order to prevent replicative stress and its deleterious consequences. During S-phase, altered progression of the replication fork by endogenous or exogenous impediments induces replicative stress, causing cells to reach mitosis with genomic regions not fully duplicated. Recently, specific mechanisms to resolve replication intermediates during mitosis with the aim of limiting DNA damage transmission to daughter cells have been identified. In this review, we detail the two major actions of specialized DNA polymerases that limit DNA damage transmission: the prevention of replicative stress by non-B DNA replication and the recovery of stalled replication forks.
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Affiliation(s)
- Elodie Bournique
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Marina Dall'Osto
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Jean-Sébastien Hoffmann
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France
| | - Valérie Bergoglio
- CRCT, Université de Toulouse, Inserm, CNRS, UPS Equipe Labellisée Ligue Contre le Cancer, Laboratoire d'Excellence Toulouse Cancer, 2 Avenue Hubert Curien, 31037, Toulouse, France.
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24
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Shima N, Pederson KD. Dormant origins as a built-in safeguard in eukaryotic DNA replication against genome instability and disease development. DNA Repair (Amst) 2017; 56:166-173. [PMID: 28641940 PMCID: PMC5547906 DOI: 10.1016/j.dnarep.2017.06.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
DNA replication is a prerequisite for cell proliferation, yet it can be increasingly challenging for a eukaryotic cell to faithfully duplicate its genome as its size and complexity expands. Dormant origins now emerge as a key component for cells to successfully accomplish such a demanding but essential task. In this perspective, we will first provide an overview of the fundamental processes eukaryotic cells have developed to regulate origin licensing and firing. With a special focus on mammalian systems, we will then highlight the role of dormant origins in preventing replication-associated genome instability and their functional interplay with proteins involved in the DNA damage repair response for tumor suppression. Lastly, deficiencies in the origin licensing machinery will be discussed in relation to their influence on stem cell maintenance and human diseases.
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Affiliation(s)
- Naoko Shima
- The University of Minnesota, Twin Cities, Department of Genetics, Cell Biology and Development, Masonic Cancer Center, 6-160 Jackson Hall, 321 Church St SE., Minneapolis, MN 55455, United States.
| | - Kayla D Pederson
- The University of Minnesota, Twin Cities, Department of Genetics, Cell Biology and Development, Masonic Cancer Center, 6-160 Jackson Hall, 321 Church St SE., Minneapolis, MN 55455, United States
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25
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Analysis of DNA polymerase ν function in meiotic recombination, immunoglobulin class-switching, and DNA damage tolerance. PLoS Genet 2017; 13:e1006818. [PMID: 28570559 PMCID: PMC5472330 DOI: 10.1371/journal.pgen.1006818] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Revised: 06/15/2017] [Accepted: 05/13/2017] [Indexed: 11/20/2022] Open
Abstract
DNA polymerase ν (pol ν), encoded by the POLN gene, is an A-family DNA polymerase in vertebrates and some other animal lineages. Here we report an in-depth analysis of pol ν–defective mice and human cells. POLN is very weakly expressed in most tissues, with the highest relative expression in testis. We constructed multiple mouse models for Poln disruption and detected no anatomic abnormalities, alterations in lifespan, or changed causes of mortality. Mice with inactive Poln are fertile and have normal testis morphology. However, pol ν–disrupted mice have a modestly reduced crossover frequency at a meiotic recombination hot spot harboring insertion/deletion polymorphisms. These polymorphisms are suggested to generate a looped-out primer and a hairpin structure during recombination, substrates on which pol ν can operate. Pol ν-defective mice had no alteration in DNA end-joining during immunoglobulin class-switching, in contrast to animals defective in the related DNA polymerase θ (pol θ). We examined the response to DNA crosslinking agents, as purified pol ν has some ability to bypass major groove peptide adducts and residues of DNA crosslink repair. Inactivation of Poln in mouse embryonic fibroblasts did not alter cellular sensitivity to mitomycin C, cisplatin, or aldehydes. Depletion of POLN from human cells with shRNA or siRNA did not change cellular sensitivity to mitomycin C or alter the frequency of mitomycin C-induced radial chromosomes. Our results suggest a function of pol ν in meiotic homologous recombination in processing specific substrates. The restricted and more recent evolutionary appearance of pol ν (in comparison to pol θ) supports such a specialized role. The work described here fills a current gap in the study of the 16 known DNA polymerases in vertebrate genomes. Until now, experiments with genetically disrupted mice have been reported for all but pol ν, encoded by the POLN gene. To intensively analyze the role of mammalian pol ν we generated multiple Poln-deficient murine models. We discovered that Poln is uniquely upregulated during testicular development and that it is enriched in spermatocytes. This, and phylogenetic analysis indicate a testis-specific function. We observed a modest reduction in meiotic recombination at a recombination hotspot in Poln-deficient mice. Pol ν has been suggested to function in DNA crosslink repair. However, we found no increased DNA crosslink sensitivity in Poln-deficient mice or POLN-depleted human cells. This is a major difference from some previous findings, and we support our conclusion by multiple experimental approaches, and by the very low or absent expression of functional pol ν in mammalian somatic cells. The present work represents the first description and comprehensive analysis of mice deficient in pol ν, and the first thorough phenotypic analysis in human cells.
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26
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Black SJ, Kashkina E, Kent T, Pomerantz RT. DNA Polymerase θ: A Unique Multifunctional End-Joining Machine. Genes (Basel) 2016; 7:E67. [PMID: 27657134 PMCID: PMC5042397 DOI: 10.3390/genes7090067] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 09/02/2016] [Accepted: 09/08/2016] [Indexed: 01/01/2023] Open
Abstract
The gene encoding DNA polymerase θ (Polθ) was discovered over ten years ago as having a role in suppressing genome instability in mammalian cells. Studies have now clearly documented an essential function for this unique A-family polymerase in the double-strand break (DSB) repair pathway alternative end-joining (alt-EJ), also known as microhomology-mediated end-joining (MMEJ), in metazoans. Biochemical and cellular studies show that Polθ exhibits a unique ability to perform alt-EJ and during this process the polymerase generates insertion mutations due to its robust terminal transferase activity which involves template-dependent and independent modes of DNA synthesis. Intriguingly, the POLQ gene also encodes for a conserved superfamily 2 Hel308-type ATP-dependent helicase domain which likely assists in alt-EJ and was reported to suppress homologous recombination (HR) via its anti-recombinase activity. Here, we review our current knowledge of Polθ-mediated end-joining, the specific activities of the polymerase and helicase domains, and put into perspective how this multifunctional enzyme promotes alt-EJ repair of DSBs formed during S and G2 cell cycle phases.
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Affiliation(s)
- Samuel J Black
- Fels Institute for Cancer Research, Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
| | - Ekaterina Kashkina
- Fels Institute for Cancer Research, Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
| | - Tatiana Kent
- Fels Institute for Cancer Research, Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
| | - Richard T Pomerantz
- Fels Institute for Cancer Research, Department of Medical Genetics and Molecular Biochemistry, Temple University Lewis Katz School of Medicine, Philadelphia, PA 19140, USA.
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27
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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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28
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Willis NA, Scully R. DNA Polymerase θ: Duct Tape and Zip Ties for a Fragile Genome. Mol Cell 2016; 63:542-544. [PMID: 27540853 DOI: 10.1016/j.molcel.2016.08.006] [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] [Indexed: 11/26/2022]
Abstract
Using a combination of genetics and cellular DNA rejoining assays, in this issue of Molecular Cell, Wyatt et al. (2016) demonstrate a critical role for mammalian DNA polymerase θ in the rejoining of DNA ends that are poor substrates for classical non-homologous end joining.
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Affiliation(s)
- Nicholas A Willis
- Department of Medicine, Division of Hematology-Oncology and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA
| | - Ralph Scully
- Department of Medicine, Division of Hematology-Oncology and Cancer Research Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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29
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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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30
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Beagan K, McVey M. Linking DNA polymerase theta structure and function in health and disease. Cell Mol Life Sci 2016; 73:603-15. [PMID: 26514729 PMCID: PMC4715478 DOI: 10.1007/s00018-015-2078-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 10/10/2015] [Accepted: 10/19/2015] [Indexed: 10/22/2022]
Abstract
DNA polymerase theta (Pol θ) is an error-prone A-family polymerase that is highly conserved among multicellular eukaryotes and plays multiple roles in DNA repair and the regulation of genome integrity. Studies conducted in several model organisms have shown that Pol θ can be utilized during DNA interstrand crosslink repair and during alternative end-joining repair of double-strand breaks. Recent genetic and biochemical studies have begun to elucidate the unique structural features of Pol θ that promote alternative end-joining repair. Importantly, Pol θ-dependent end joining appears to be important for overall genome stability, as it affects chromosome translocation formation in murine and human cell lines. Pol θ has also been suggested to act as a modifier of replication timing in human cells, though the mechanism of action remains unknown. Pol θ is highly upregulated in a number of human cancer types, which could indicate that mutagenic Pol θ-dependent end joining is used during cancer cell proliferation. Here, we review the various roles of Pol θ across species and discuss how these roles may be relevant to cancer therapy.
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Affiliation(s)
- Kelly Beagan
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA, 02155, USA
| | - Mitch McVey
- Department of Biology, Tufts University, 200 Boston Avenue, Suite 4700, Medford, MA, 02155, USA.
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31
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Newman JA, Cooper CDO, Aitkenhead H, Gileadi O. Structure of the Helicase Domain of DNA Polymerase Theta Reveals a Possible Role in the Microhomology-Mediated End-Joining Pathway. Structure 2015; 23:2319-2330. [PMID: 26636256 PMCID: PMC4671958 DOI: 10.1016/j.str.2015.10.014] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 10/06/2015] [Accepted: 10/09/2015] [Indexed: 12/21/2022]
Abstract
DNA polymerase theta (Polθ) has been identified as a crucial alternative non-homologous end-joining factor in mammalian cells. Polθ is upregulated in a range of cancer cell types defective in homologous recombination, and knockdown has been shown to inhibit cell survival in a subset of these, making it an attractive target for cancer treatment. We present crystal structures of the helicase domain of human Polθ in the presence and absence of bound nucleotides, and a characterization of its DNA-binding and DNA-stimulated ATPase activities. Comparisons with related helicases from the Hel308 family identify several unique features. Polθ exists as a tetramer both in the crystals and in solution. We propose a model for DNA binding to the Polθ helicase domain in the context of the Polθ tetramer, which suggests a role for the helicase domain in strand annealing of DNA templates for subsequent processing by the polymerase domain.
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Affiliation(s)
- Joseph A Newman
- Structural Genomics Consortium, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Christopher D O Cooper
- Structural Genomics Consortium, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Hazel Aitkenhead
- Structural Genomics Consortium, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK
| | - Opher Gileadi
- Structural Genomics Consortium, University of Oxford, ORCRB, Roosevelt Drive, Oxford OX3 7DQ, UK.
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32
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Leibowitz ML, Zhang CZ, Pellman D. Chromothripsis: A New Mechanism for Rapid Karyotype Evolution. Annu Rev Genet 2015; 49:183-211. [DOI: 10.1146/annurev-genet-120213-092228] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Mitchell L. Leibowitz
- Department of Pediatric Oncology,
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115;
| | - Cheng-Zhong Zhang
- Department of Pediatric Oncology,
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215;
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115;
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142;
| | - David Pellman
- Department of Pediatric Oncology,
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115;
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142;
- Howard Hughes Medical Institute, Boston, Massachusetts 02115
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33
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van Schendel R, Roerink SF, Portegijs V, van den Heuvel S, Tijsterman M. Polymerase Θ is a key driver of genome evolution and of CRISPR/Cas9-mediated mutagenesis. Nat Commun 2015; 6:7394. [PMID: 26077599 PMCID: PMC4490562 DOI: 10.1038/ncomms8394] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 05/04/2015] [Indexed: 12/22/2022] Open
Abstract
Cells are protected from toxic DNA double-stranded breaks (DSBs) by a number of DNA repair mechanisms, including some that are intrinsically error prone, thus resulting in mutations. To what extent these mechanisms contribute to evolutionary diversification remains unknown. Here, we demonstrate that the A-family polymerase theta (POLQ) is a major driver of inheritable genomic alterations in Caenorhabditis elegans. Unlike somatic cells, which use non-homologous end joining (NHEJ) to repair DNA transposon-induced DSBs, germ cells use polymerase theta-mediated end joining, a conceptually simple repair mechanism requiring only one nucleotide as a template for repair. Also CRISPR/Cas9-induced genomic changes are exclusively generated through polymerase theta-mediated end joining, refuting a previously assumed requirement for NHEJ in their formation. Finally, through whole-genome sequencing of propagated populations, we show that only POLQ-proficient animals accumulate genomic scars that are abundantly present in genomes of wild C. elegans, pointing towards POLQ as a major driver of genome diversification.
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Affiliation(s)
- Robin van Schendel
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300 RC, Leiden, The Netherlands
| | - Sophie F. Roerink
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300 RC, Leiden, The Netherlands
| | - Vincent Portegijs
- Department of Biology, Division of Developmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Sander van den Heuvel
- Department of Biology, Division of Developmental Biology, Utrecht University, Padualaan 8, 3584 CH, Utrecht, The Netherlands
| | - Marcel Tijsterman
- Department of Human Genetics, Leiden University Medical Center, PO Box 9600, 2300 RC, Leiden, The Netherlands
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34
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Zahn KE, Averill AM, Aller P, Wood RD, Doublié S. Human DNA polymerase θ grasps the primer terminus to mediate DNA repair. Nat Struct Mol Biol 2015; 22:304-11. [PMID: 25775267 PMCID: PMC4385486 DOI: 10.1038/nsmb.2993] [Citation(s) in RCA: 100] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Accepted: 02/13/2015] [Indexed: 01/14/2023]
Abstract
DNA polymerase θ protects against genomic instability via an alternative end-joining repair pathway for DNA double-strand breaks. Polymerase θ is overexpressed in breast, lung and oral cancers, and reduction of its activity in mammalian cells increases sensitivity to double-strand break-inducing agents, including ionizing radiation. Reported here are crystal structures of the C-terminal polymerase domain from human polymerase θ, illustrating two potential modes of dimerization. One structure depicts insertion of ddATP opposite an abasic-site analog during translesion DNA synthesis. The second structure describes a cognate ddGTP complex. Polymerase θ uses a specialized thumb subdomain to establish unique upstream contacts to the primer DNA strand, including an interaction with the 3'-terminal phosphate from one of five distinctive insertion loops. These observations demonstrate how polymerase θ grasps the primer to bypass DNA lesions or extend poorly annealed DNA termini to mediate end-joining.
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Affiliation(s)
- Karl E Zahn
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | - April M Averill
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
| | | | - Richard D Wood
- Department of Epigenetics &Molecular Carcinogenesis, University of Texas MD Anderson Cancer Center, Smithville, Texas, USA
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, Vermont, USA
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35
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Mateos-Gomez PA, Gong F, Nair N, Miller KM, Lazzerini-Denchi E, Sfeir A. Mammalian polymerase θ promotes alternative NHEJ and suppresses recombination. Nature 2015; 518:254-7. [PMID: 25642960 PMCID: PMC4718306 DOI: 10.1038/nature14157] [Citation(s) in RCA: 519] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 12/16/2014] [Indexed: 12/11/2022]
Abstract
The alternative non-homologous end-joining (NHEJ) machinery facilitates several genomic rearrangements, some of which can lead to cellular transformation. This error-prone repair pathway is triggered upon telomere de-protection to promote the formation of deleterious chromosome end-to-end fusions. Using next-generation sequencing technology, here we show that repair by alternative NHEJ yields non-TTAGGG nucleotide insertions at fusion breakpoints of dysfunctional telomeres. Investigating the enzymatic activity responsible for the random insertions enabled us to identify polymerase theta (Polθ; encoded by Polq in mice) as a crucial alternative NHEJ factor in mammalian cells. Polq inhibition suppresses alternative NHEJ at dysfunctional telomeres, and hinders chromosomal translocations at non-telomeric loci. In addition, we found that loss of Polq in mice results in increased rates of homology-directed repair, evident by recombination of dysfunctional telomeres and accumulation of RAD51 at double-stranded breaks. Lastly, we show that depletion of Polθ has a synergistic effect on cell survival in the absence of BRCA genes, suggesting that the inhibition of this mutagenic polymerase represents a valid therapeutic avenue for tumours carrying mutations in homology-directed repair genes.
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Affiliation(s)
- Pedro A. Mateos-Gomez
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
| | - Fade Gong
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin. 2506 Speedway Stop A5000, Austin, TX 78712 USA
| | - Nidhi Nair
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kyle M. Miller
- Department of Molecular Biosciences, Institute for Cellular and Molecular Biology, University of Texas at Austin. 2506 Speedway Stop A5000, Austin, TX 78712 USA
| | - Eros Lazzerini-Denchi
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Agnel Sfeir
- Skirball Institute of Biomolecular Medicine, Department of Cell Biology, NYU School of Medicine, New York, NY 10016, USA
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36
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Balmus G, Karp NA, Ng BL, Jackson SP, Adams DJ, McIntyre RE. A high-throughput in vivo micronucleus assay for genome instability screening in mice. Nat Protoc 2015; 10:205-15. [PMID: 25551665 PMCID: PMC4806852 DOI: 10.1038/nprot.2015.010] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We describe a sensitive, robust, high-throughput method for quantifying the formation of micronuclei, markers of genome instability, in mouse erythrocytes. Micronuclei are whole chromosomes or chromosome segments that have been separated from the nucleus. Other methods of detection rely on labor-intensive, microscopy-based techniques. Here we describe a 2-d, 96-well plate-based flow cytometric method of micronucleus scoring that is simple enough for a research technician experienced in flow cytometry to perform. The assay detects low levels of genome instability that cannot be readily identified by classic phenotyping, using 25 μl of blood. By using this assay, we have screened >10,000 blood samples and discovered novel genes that contribute to vertebrate genome maintenance, as well as novel disease models and mechanisms of genome instability disorders. We discuss experimental design considerations, including statistical power calculation, we provide troubleshooting tips and we discuss factors that contribute to a false-positive increase in the number of micronucleated red blood cells and to experimental variability.
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Affiliation(s)
- Gabriel Balmus
- The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Maintenance of Genome Stability; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Natasha A Karp
- Mouse Genetics Project; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Bee Ling Ng
- Cytometry Core Facility; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Stephen P Jackson
- The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
- Maintenance of Genome Stability; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - David J Adams
- Experimental Cancer Genetics; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
| | - Rebecca E McIntyre
- Experimental Cancer Genetics; The Wellcome Trust Sanger Institute, Genome Campus, Hinxton, Cambridge, CB10 1SA, UK
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37
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Yousefzadeh MJ, Wyatt DW, Takata KI, Mu Y, Hensley SC, Tomida J, Bylund GO, Doublié S, Johansson E, Ramsden DA, McBride KM, Wood RD. Mechanism of suppression of chromosomal instability by DNA polymerase POLQ. PLoS Genet 2014; 10:e1004654. [PMID: 25275444 PMCID: PMC4183433 DOI: 10.1371/journal.pgen.1004654] [Citation(s) in RCA: 197] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 08/05/2014] [Indexed: 12/13/2022] Open
Abstract
Although a defect in the DNA polymerase POLQ leads to ionizing radiation sensitivity in mammalian cells, the relevant enzymatic pathway has not been identified. Here we define the specific mechanism by which POLQ restricts harmful DNA instability. Our experiments show that Polq-null murine cells are selectively hypersensitive to DNA strand breaking agents, and that damage resistance requires the DNA polymerase activity of POLQ. Using a DNA break end joining assay in cells, we monitored repair of DNA ends with long 3' single-stranded overhangs. End joining events retaining much of the overhang were dependent on POLQ, and independent of Ku70. To analyze the repair function in more detail, we examined immunoglobulin class switch joining between DNA segments in antibody genes. POLQ participates in end joining of a DNA break during immunoglobulin class-switching, producing insertions of base pairs at the joins with homology to IgH switch-region sequences. Biochemical experiments with purified human POLQ protein revealed the mechanism generating the insertions during DNA end joining, relying on the unique ability of POLQ to extend DNA from minimally paired primers. DNA breaks at the IgH locus can sometimes join with breaks in Myc, creating a chromosome translocation. We found a marked increase in Myc/IgH translocations in Polq-defective mice, showing that POLQ suppresses genomic instability and genome rearrangements originating at DNA double-strand breaks. This work clearly defines a role and mechanism for mammalian POLQ in an alternative end joining pathway that suppresses the formation of chromosomal translocations. Our findings depart from the prevailing view that alternative end joining processes are generically translocation-prone.
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Affiliation(s)
- Matthew J. Yousefzadeh
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - David W. Wyatt
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kei-ichi Takata
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Yunxiang Mu
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
| | - Sean C. Hensley
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
| | - Junya Tomida
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Göran O. Bylund
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Sylvie Doublié
- Department of Microbiology and Molecular Genetics, The University of Vermont, Burlington, Vermont
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Dale A. Ramsden
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Kevin M. McBride
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
| | - Richard D. Wood
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, Texas, United States of America
- The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas, United States of America
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38
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Meier B, Gartner A. Having a direct look: analysis of DNA damage and repair mechanisms by next generation sequencing. Exp Cell Res 2014; 329:35-41. [PMID: 25131498 PMCID: PMC4432029 DOI: 10.1016/j.yexcr.2014.08.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 08/04/2014] [Indexed: 11/25/2022]
Abstract
Genetic information is under constant attack from endogenous and exogenous sources, and the use of model organisms has provided important frameworks to understand how genome stability is maintained and how various DNA lesions are repaired. The advance of high throughput next generation sequencing (NGS) provides new inroads for investigating mechanisms needed for genome maintenance. These emerging studies, which aim to link genetic toxicology and mechanistic analyses of DNA repair processes in vivo, rely on defining mutational signatures caused by faulty replication, endogenous DNA damaging metabolites, or exogenously applied genotoxins; the analysis of their nature, their frequency and distribution. In contrast to classical studies, where DNA repair deficiency is assessed by reduced cellular survival, the localization of DNA repair factors and their interdependence as well as limited analysis of single locus reporter assays, NGS based approaches reveal the direct, quantal imprint of mutagenesis genome-wide, at the DNA sequence level. As we will show, such investigations require the analysis of DNA derived from single genotoxin treated cells, or DNA from cell populations regularly passaged through single cell bottlenecks when naturally occurring mutation accumulation is investigated. We will argue that the life cycle of the nematode Caenorhabditis elegans, its genetic malleability combined with whole genome sequencing provides an exciting model system to conduct such analysis.
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Affiliation(s)
- Bettina Meier
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, UK
| | - Anton Gartner
- Centre for Gene Regulation and Expression, University of Dundee, Dundee, UK.
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39
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Stottmann R, Beier DR. ENU Mutagenesis in the Mouse. CURRENT PROTOCOLS IN HUMAN GENETICS 2014; 82:15.4.1-15.4.10. [PMID: 25042716 PMCID: PMC4113905 DOI: 10.1002/0471142905.hg1504s82] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
This unit describes the treatment of laboratory mice with the mutagen N-ethyl-N-nitrosourea (ENU) to induce very highly increased rates of mutation throughout the genome. Further, it describes several popular mating schemes designed to produce animals displaying phenotypes associated with the induced mutations.
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Affiliation(s)
- Rolf Stottmann
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - David R. Beier
- Center for Developmental Biology and Regenerative Medicine, Seattle Children’s Research Institute
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40
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Luo Y, Hartford SA, Zeng R, Southard TL, Shima N, Schimenti JC. Hypersensitivity of primordial germ cells to compromised replication-associated DNA repair involves ATM-p53-p21 signaling. PLoS Genet 2014; 10:e1004471. [PMID: 25010009 PMCID: PMC4091704 DOI: 10.1371/journal.pgen.1004471] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 05/14/2014] [Indexed: 01/12/2023] Open
Abstract
Genome maintenance in germ cells is critical for fertility and the stable propagation of species. While mechanisms of meiotic DNA repair and chromosome behavior are well-characterized, the same is not true for primordial germ cells (PGCs), which arise and propagate during very early stages of mammalian development. Fanconi anemia (FA), a genomic instability syndrome that includes hypogonadism and testicular failure phenotypes, is caused by mutations in genes encoding a complex of proteins involved in repair of DNA lesions associated with DNA replication. The signaling mechanisms underlying hypogonadism and testicular failure in FA patients or mouse models are unknown. We conducted genetic studies to show that hypogonadism of Fancm mutant mice is a result of reduced proliferation, but not apoptosis, of PGCs, resulting in reduced germ cells in neonates of both sexes. Progressive loss of germ cells in adult males also occurs, overlaid with an elevated level of meiotic DNA damage. Genetic studies indicated that ATM-p53-p21 signaling is partially responsible for the germ cell deficiency. The precursors to sperm and eggs begin are a group of <100 cells in the embryo, called primordial germ cells (PGCs). They migrate in the primitive embryo to the location of the future gonads, then undergo a rapid proliferation over the next few days to a population of many thousands. Because these cells contain the precious genetic information for our offspring, and the DNA replication associated with rapid PGC proliferation is subject to spontaneous errors, mechanisms exist to avoid propagation of mutations. A manifestation of this is the high sensitivity of PGCs to genetic perturbations affecting DNA repair. We studied mice defective for a gene called Fanconi anemia M (Fancm) that is important for repair of DNA damage that occurs during replication. Although it is expressed in all tissues, only the PGCs are affected in mutants, and are reduced in number. We find that PGCs lacking Fancm respond by slowing cell division, and identified the genetic pathway responsible for this protective response.
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Affiliation(s)
- Yunhai Luo
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - Suzanne A Hartford
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - Ruizhu Zeng
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - Teresa L Southard
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - Naoko Shima
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
| | - John C Schimenti
- Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America
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41
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Fernandez-Vidal A, Guitton-Sert L, Cadoret JC, Drac M, Schwob E, Baldacci G, Cazaux C, Hoffmann JS. A role for DNA polymerase θ in the timing of DNA replication. Nat Commun 2014; 5:4285. [PMID: 24989122 DOI: 10.1038/ncomms5285] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 06/03/2014] [Indexed: 01/01/2023] Open
Abstract
Although DNA polymerase θ (Pol θ) is known to carry out translesion synthesis and has been implicated in DNA repair, its physiological function under normal growth conditions remains unclear. Here we present evidence that Pol θ plays a role in determining the timing of replication in human cells. We find that Pol θ binds to chromatin during early G1, interacts with the Orc2 and Orc4 components of the Origin recognition complex and that the association of Mcm proteins with chromatin is enhanced in G1 when Pol θ is downregulated. Pol θ-depleted cells exhibit a normal density of activated origins in S phase, but early-to-late and late-to-early shifts are observed at a number of replication domains. Pol θ overexpression, on the other hand, causes delayed replication. Our results therefore suggest that Pol θ functions during the earliest steps of DNA replication and influences the timing of replication initiation.
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Affiliation(s)
- Anne Fernandez-Vidal
- 1] Equipe Labellisée Ligue contre le Cancer 2013 INSERM Unit 1037; CNRS ERL 5294; CRCT (Cancer Research Center of Toulouse), BP3028, CHU Purpan, Toulouse 31024, France [2] Université Paul Sabatier, University of Toulouse III, Toulouse F-31062, France [3]
| | - Laure Guitton-Sert
- 1] Equipe Labellisée Ligue contre le Cancer 2013 INSERM Unit 1037; CNRS ERL 5294; CRCT (Cancer Research Center of Toulouse), BP3028, CHU Purpan, Toulouse 31024, France [2] Université Paul Sabatier, University of Toulouse III, Toulouse F-31062, France [3]
| | - Jean-Charles Cadoret
- 1] Institut Jacques Monod, UMR7592, CNRS and University Paris-Diderot, 15 Rue Hélène Brion, Paris, Cedex 13 75205, France [2]
| | - Marjorie Drac
- Institut of Molecular Genetics, CNRS UMR5535 and University of Montpellier, Montpellier 34293, France
| | - Etienne Schwob
- Institut of Molecular Genetics, CNRS UMR5535 and University of Montpellier, Montpellier 34293, France
| | - Giuseppe Baldacci
- Institut Jacques Monod, UMR7592, CNRS and University Paris-Diderot, 15 Rue Hélène Brion, Paris, Cedex 13 75205, France
| | - Christophe Cazaux
- 1] Equipe Labellisée Ligue contre le Cancer 2013 INSERM Unit 1037; CNRS ERL 5294; CRCT (Cancer Research Center of Toulouse), BP3028, CHU Purpan, Toulouse 31024, France [2] Université Paul Sabatier, University of Toulouse III, Toulouse F-31062, France
| | - Jean-Sébastien Hoffmann
- 1] Equipe Labellisée Ligue contre le Cancer 2013 INSERM Unit 1037; CNRS ERL 5294; CRCT (Cancer Research Center of Toulouse), BP3028, CHU Purpan, Toulouse 31024, France [2] Université Paul Sabatier, University of Toulouse III, Toulouse F-31062, France
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42
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Abstract
This article describes the treatment of laboratory mice with the mutagen N-ethyl-N-nitrosourea (ENU) to induce very highly increased rates of mutation throughout the genome. Further, it describes several popular mating schemes designed to produce animals displaying phenotypes associated with the induced mutations.
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Affiliation(s)
- Rolf Stottmann
- Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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43
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Luebben SW, Kawabata T, Akre MK, Lee WL, Johnson CS, O'Sullivan MG, Shima N. Helq acts in parallel to Fancc to suppress replication-associated genome instability. Nucleic Acids Res 2013; 41:10283-97. [PMID: 24005041 PMCID: PMC3905894 DOI: 10.1093/nar/gkt676] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
HELQ is a superfamily 2 DNA helicase found in archaea and metazoans. It has been implicated in processing stalled replication forks and in repairing DNA double-strand breaks and inter-strand crosslinks. Though previous studies have suggested the possibility that HELQ is involved in the Fanconi anemia (FA) pathway, a dominant mechanism for inter-strand crosslink repair in vertebrates, this connection remains elusive. Here, we investigated this question in mice using the Helqgt and Fancc− strains. Compared with Fancc−/− mice lacking FANCC, a component of the FA core complex, Helqgt/gt mice exhibited a mild of form of FA-like phenotypes including hypogonadism and cellular sensitivity to the crosslinker mitomycin C. However, unlike Fancc−/− primary fibroblasts, Helqgt/gt cells had intact FANCD2 mono-ubiquitination and focus formation. Notably, for all traits examined, Helq was non-epistatic with Fancc, as Helqgt/gt;Fancc−/− double mutants displayed significantly worsened phenotypes than either single mutant. Importantly, this was most noticeable for the suppression of spontaneous chromosome instability such as micronuclei and 53BP1 nuclear bodies, known consequences of persistently stalled replication forks. These findings suggest that mammalian HELQ contributes to genome stability in unchallenged conditions through a mechanism distinct from the function of FANCC.
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Affiliation(s)
- Spencer W Luebben
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN 55455, USA, Molecular, Cellular, Developmental Biology and Genetics Graduate Program, University of Minnesota, Minneapolis, MN 55455, USA, Masonic Cancer Center, Minneapolis, MN 55455, USA and College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55108, USA
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44
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van der Weyden L, Adams DJ. Cancer of mice and men: old twists and new tails. J Pathol 2013; 230:4-16. [PMID: 23436574 DOI: 10.1002/path.4184] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 01/28/2013] [Accepted: 02/16/2013] [Indexed: 12/18/2022]
Abstract
In this review we set out to celebrate the contribution that mouse models of human cancer have made to our understanding of the fundamental mechanisms driving tumourigenesis. We take the opportunity to look forward to how the mouse will be used to model cancer and the tools and technologies that will be applied, and indulge in looking back at the key advances the mouse has made possible.
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45
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Chen J, Ingham N, Clare S, Raisen C, Vancollie VE, Ismail O, McIntyre RE, Tsang SH, Mahajan VB, Dougan G, Adams DJ, White JK, Steel KP. Mcph1-deficient mice reveal a role for MCPH1 in otitis media. PLoS One 2013; 8:e58156. [PMID: 23516444 PMCID: PMC3596415 DOI: 10.1371/journal.pone.0058156] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Accepted: 01/31/2013] [Indexed: 12/20/2022] Open
Abstract
Otitis media is a common reason for hearing loss, especially in children. Otitis media is a multifactorial disease and environmental factors, anatomic dysmorphology and genetic predisposition can all contribute to its pathogenesis. However, the reasons for the variable susceptibility to otitis media are elusive. MCPH1 mutations cause primary microcephaly in humans. So far, no hearing impairment has been reported either in the MCPH1 patients or mouse models with Mcph1 deficiency. In this study, Mcph1-deficient (Mcph1tm1a/tm1a) mice were produced using embryonic stem cells with a targeted mutation by the Sanger Institute's Mouse Genetics Project. Auditory brainstem response measurements revealed that Mcph1tm1a/tm1a mice had mild to moderate hearing impairment with around 70% penetrance. We found otitis media with effusion in the hearing-impaired Mcph1tm1a/tm1a mice by anatomic and histological examinations. Expression of Mcph1 in the epithelial cells of middle ear cavities supported its involvement in the development of otitis media. Other defects of Mcph1tm1a/tm1a mice included small skull sizes, increased micronuclei in red blood cells, increased B cells and ocular abnormalities. These findings not only recapitulated the defects found in other Mcph1-deficient mice or MCPH1 patients, but also revealed an unexpected phenotype, otitis media with hearing impairment, which suggests Mcph1 is a new gene underlying genetic predisposition to otitis media.
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Affiliation(s)
- Jing Chen
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Neil Ingham
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Simon Clare
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Claire Raisen
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | | | - Ozama Ismail
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | | | - Stephen H. Tsang
- Edward S. Harkness Eye Institute, Columbia University, New York, New York, United States of America
| | - Vinit B. Mahajan
- Omics Laboratory, Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States of America
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | - David J. Adams
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
| | | | - Karen P. Steel
- Wellcome Trust Sanger Institute, Hinxton, Cambridgeshire, United Kingdom
- * E-mail:
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46
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Yousefzadeh MJ, Wood RD. DNA polymerase POLQ and cellular defense against DNA damage. DNA Repair (Amst) 2013; 12:1-9. [PMID: 23219161 PMCID: PMC3534860 DOI: 10.1016/j.dnarep.2012.10.004] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2012] [Accepted: 10/15/2012] [Indexed: 12/15/2022]
Abstract
In mammalian cells, POLQ (pol θ) is an unusual specialized DNA polymerase whose in vivo function is under active investigation. POLQ has been implicated by different experiments to play a role in resistance to ionizing radiation and defense against genomic instability, in base excision repair, and in immunological diversification. The protein is formed by an N-terminal helicase-like domain, a C-terminal DNA polymerase domain, and a large central domain that spans between the two. This arrangement is also found in the Drosophila Mus308 protein, which functions in resistance to DNA interstrand crosslinking agents. Homologs of POLQ and Mus308 are found in multicellular eukaryotes, including plants, but a comparison of phenotypes suggests that not all of these genes are functional orthologs. Flies defective in Mus308 are sensitive to DNA interstrand crosslinking agents, while mammalian cells defective in POLQ are primarily sensitive to DNA double-strand breaking agents. Cells from Polq(-/-) mice are hypersensitive to radiation and peripheral blood cells display increased spontaneous and ionizing radiation-induced levels of micronuclei (a hallmark of gross chromosomal aberrations), though mice apparently develop normally. Loss of POLQ in human and mouse cells causes sensitivity to ionizing radiation and other double strand breaking agents and increased DNA damage signaling. Retrospective studies of clinical samples show that higher levels of POLQ gene expression in breast and colorectal cancer are correlated with poorer outcomes for patients. A clear understanding of the mechanism of action and physiologic function of POLQ in the cell is likely to bear clinical relevance.
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Affiliation(s)
- Matthew J Yousefzadeh
- Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, P.O. Box 389, Smithville, TX 78957, USA
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47
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Sharma S, Canman CE. REV1 and DNA polymerase zeta in DNA interstrand crosslink repair. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2012; 53:725-40. [PMID: 23065650 PMCID: PMC5543726 DOI: 10.1002/em.21736] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 08/09/2012] [Accepted: 08/15/2012] [Indexed: 05/06/2023]
Abstract
DNA interstrand crosslinks (ICLs) are covalent linkages between two strands of DNA, and their presence interferes with essential metabolic processes such as transcription and replication. These lesions are extremely toxic, and their repair is essential for genome stability and cell survival. In this review, we will discuss how the removal of ICLs requires interplay between multiple genome maintenance pathways and can occur in the absence of replication (replication-independent ICL repair) or during S phase (replication-coupled ICL repair), the latter being the predominant pathway used in mammalian cells. It is now well recognized that translesion DNA synthesis (TLS), especially through the activities of REV1 and DNA polymerase zeta (Polζ), is necessary for both ICL repair pathways operating throughout the cell cycle. Recent studies suggest that the convergence of two replication forks upon an ICL initiates a cascade of events including unhooking of the lesion through the actions of structure-specific endonucleases, thereby creating a DNA double-stranded break (DSB). TLS across the unhooked lesion is necessary for restoring the sister chromatid before homologous recombination repair. Biochemical and genetic studies implicate REV1 and Polζ as being essential for performing lesion bypass across the unhooked crosslink, and this step appears to be important for subsequent events to repair the intermediate DSB. The potential role of Fanconi anemia pathway in the regulation of REV1 and Polζ-dependent TLS and the involvement of additional polymerases, including DNA polymerases kappa, nu, and theta, in the repair of ICLs is also discussed in this review.
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Affiliation(s)
- Shilpy Sharma
- Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109-2200, USA
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48
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High throughput sequencing approaches to mutation discovery in the mouse. Mamm Genome 2012; 23:499-513. [PMID: 22991087 DOI: 10.1007/s00335-012-9424-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2012] [Accepted: 07/19/2012] [Indexed: 12/19/2022]
Abstract
Phenotype-driven approaches in mice are powerful strategies for the discovery of genes and gene functions and for unravelling complex biological mechanisms. Traditional methods for mutation discovery are reliable and robust, but they can also be laborious and time consuming. Recently, high-throughput sequencing (HTS) technologies have revolutionised the process of forward genetics in mice by paving the way to rapid mutation discovery. However, successful application of HTS for mutation discovery relies heavily on the sequencing approach employed and strategies for data analysis. Here we review current HTS applications and resources for mutation discovery and provide an overview of the practical considerations for HTS implementation and data analysis.
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49
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Balmus G, Zhu M, Mukherjee S, Lyndaker AM, Hume KR, Lee J, Riccio ML, Reeves AP, Sutter NB, Noden DM, Peters RM, Weiss RS. Disease severity in a mouse model of ataxia telangiectasia is modulated by the DNA damage checkpoint gene Hus1. Hum Mol Genet 2012; 21:3408-20. [PMID: 22575700 DOI: 10.1093/hmg/dds173] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The human genomic instability syndrome ataxia telangiectasia (A-T), caused by mutations in the gene encoding the DNA damage checkpoint kinase ATM, is characterized by multisystem defects including neurodegeneration, immunodeficiency and increased cancer predisposition. ATM is central to a pathway that responds to double-strand DNA breaks, whereas the related kinase ATR leads a parallel signaling cascade that is activated by replication stress. To dissect the physiological relationship between the ATM and ATR pathways, we generated mice defective for both. Because complete ATR pathway inactivation causes embryonic lethality, we weakened the ATR mechanism to different degrees by impairing HUS1, a member of the 911 complex that is required for efficient ATR signaling. Notably, simultaneous ATM and HUS1 defects caused synthetic lethality. Atm/Hus1 double-mutant embryos showed widespread apoptosis and died mid-gestationally. Despite the underlying DNA damage checkpoint defects, increased DNA damage signaling was observed, as evidenced by H2AX phosphorylation and p53 accumulation. A less severe Hus1 defect together with Atm loss resulted in partial embryonic lethality, with the surviving double-mutant mice showing synergistic increases in genomic instability and specific developmental defects, including dwarfism, craniofacial abnormalities and brachymesophalangy, phenotypes that are observed in several human genomic instability disorders. In addition to identifying tissue-specific consequences of checkpoint dysfunction, these data highlight a robust, cooperative configuration for the mammalian DNA damage response network and further suggest HUS1 and related genes in the ATR pathway as candidate modifiers of disease severity in A-T patients.
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Affiliation(s)
- Gabriel Balmus
- Department of Biomedical Sciences, Cornell University, Ithaca, NY 14853, USA
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50
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Hogg M, Sauer-Eriksson AE, Johansson E. Promiscuous DNA synthesis by human DNA polymerase θ. Nucleic Acids Res 2012; 40:2611-22. [PMID: 22135286 PMCID: PMC3315306 DOI: 10.1093/nar/gkr1102] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 11/03/2011] [Accepted: 11/04/2011] [Indexed: 12/15/2022] Open
Abstract
The biological role of human DNA polymerase θ (POLQ) is not yet clearly defined, but it has been proposed to participate in several cellular processes based on its translesion synthesis capabilities. POLQ is a low-fidelity polymerase capable of efficient bypass of blocking lesions such as abasic sites and thymine glycols as well as extension of mismatched primer termini. Here, we show that POLQ possesses a DNA polymerase activity that appears to be template independent and allows efficient extension of single-stranded DNA as well as duplex DNA with either protruding or multiply mismatched 3'-OH termini. We hypothesize that this DNA synthesis activity is related to the proposed role for POLQ in the repair or tolerance of double-strand breaks.
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Affiliation(s)
- Matthew Hogg
- Department of Medical Biochemistry and Biophysics and Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - A. Elisabeth Sauer-Eriksson
- Department of Medical Biochemistry and Biophysics and Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
| | - Erik Johansson
- Department of Medical Biochemistry and Biophysics and Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden
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