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Zhong W, Sczepanski JT. Chimeric d/l-DNA Probes of Base Excision Repair Enable Real-Time Monitoring of Thymine DNA Glycosylase Activity in Live Cells. J Am Chem Soc 2023; 145:17066-17074. [PMID: 37493592 PMCID: PMC10416308 DOI: 10.1021/jacs.3c03010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Indexed: 07/27/2023]
Abstract
The base excision repair (BER) pathway is a frontline defender of genomic integrity and plays a central role in epigenetic regulation through its involvement in the erasure of 5-methylcytosine. This biological and clinical significance has led to a demand for analytical methods capable of monitoring BER activities, especially in living cells. Unfortunately, prevailing methods, which are primarily derived from nucleic acids, are mostly incompatible with intracellular use due to their susceptibility to nuclease degradation and other off-target interactions. These limitations preclude important biological studies of BER enzymes and many clinical applications. Herein, we report a straightforward approach for constructing biostable BER probes using a unique chimeric d/l-DNA architecture that exploits the bioorthogonal properties of mirror-image l-DNA. We show that chimeric BER probes have excellent stability within living cells, where they were successfully employed to monitor relative BER activity, evaluate the efficiency of small molecule BER inhibitors, and study enzyme mutants. Notably, we report the first example of a fluorescent probe for real-time monitoring of thymine DNA glycosylase (TDG)-mediated BER of 5-formylcytosine and 5-carboxylcytosine in living cells, providing a much-needed tool for studying DNA (de)methylation biology. Chimeric probes offer a robust and highly generalizable approach for real-time monitoring of BER activity in living cells, which should enable a broad spectrum of basic research and clinical applications.
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Affiliation(s)
- Wenrui Zhong
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
| | - Jonathan T. Sczepanski
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
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2
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Signal-on/signal-off bead-based assays for the multiplexed monitoring of base excision repair activities by flow cytometry. Anal Bioanal Chem 2022; 414:2029-2040. [DOI: 10.1007/s00216-021-03849-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 12/03/2021] [Accepted: 12/13/2021] [Indexed: 11/01/2022]
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3
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Kladova OA, Iakovlev DA, Groisman R, Ishchenko AA, Saparbaev MK, Fedorova OS, Kuznetsov NA. An Assay for the Activity of Base Excision Repair Enzymes in Cellular Extracts Using Fluorescent DNA Probes. BIOCHEMISTRY (MOSCOW) 2021; 85:480-489. [PMID: 32569555 DOI: 10.1134/s0006297920040082] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Damaged DNA bases are removed by the base excision repair (BER) mechanism. This enzymatic process begins with the action of one of DNA glycosylases, which recognize damaged DNA bases and remove them by hydrolyzing N-glycosidic bonds with the formation of apurinic/apyrimidinic (AP) sites. Apurinic/apyrimidinic endonuclease 1 (APE1) hydrolyzes the phosphodiester bond on the 5'-side of the AP site with generation of the single-strand DNA break. A decrease in the functional activity of BER enzymes is associated with the increased risk of cardiovascular, neurodegenerative, and oncological diseases. In this work, we developed a fluorescence method for measuring the activity of key human DNA glycosylases and AP endonuclease in cell extracts. The efficacy of fluorescent DNA probes was tested using purified enzymes; the most efficient probes were tested in the enzymatic activity assays in the extracts of A549, MCF7, HeLa, WT-7, HEK293T, and HKC8 cells. The activity of enzymes responsible for the repair of AP sites and removal of uracil and 5,6-dihydrouracil residues was higher in cancer cell lines as compared to the normal HKC8 human kidney cell line.
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Affiliation(s)
- O A Kladova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - D A Iakovlev
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia
| | - R Groisman
- Groupe "Réparation de l'AND", Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Université Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France.,Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France
| | - A A Ishchenko
- Groupe "Réparation de l'AND", Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Université Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France.,Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France
| | - M K Saparbaev
- Groupe "Réparation de l'AND", Equipe Labellisée par la Ligue Nationale contre le Cancer, CNRS UMR 8200, Université Paris-Sud, Université Paris-Saclay, Villejuif, F-94805, France.,Gustave Roussy, Université Paris-Saclay, Villejuif, F-94805, France
| | - O S Fedorova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Novosibirsk State University, Novosibirsk, 630090, Russia
| | - N A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090, Russia. .,Novosibirsk State University, Novosibirsk, 630090, Russia
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4
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Healing E, Charlier CF, Meira LB, Elliott RM. A panel of colorimetric assays to measure enzymatic activity in the base excision DNA repair pathway. Nucleic Acids Res 2019; 47:e61. [PMID: 30869144 PMCID: PMC6582407 DOI: 10.1093/nar/gkz171] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/13/2019] [Accepted: 03/07/2019] [Indexed: 12/12/2022] Open
Abstract
DNA repair is essential for the maintenance of genomic integrity, and evidence suggest that inter-individual variation in DNA repair efficiency may contribute to disease risk. However, robust assays suitable for quantitative determination of DNA repair capacity in large cohort and clinical trials are needed to evaluate these apparent associations fully. We describe here a set of microplate-based oligonucleotide assays for high-throughput, non-radioactive and quantitative determination of repair enzyme activity at individual steps and over multiple steps of the DNA base excision repair pathway. The assays are highly sensitive: using HepG2 nuclear extract, enzyme activities were quantifiable at concentrations of 0.0002 to 0.181 μg per reaction, depending on the enzyme being measured. Assay coefficients of variation are comparable with other microplate-based assays. The assay format requires no specialist equipment and has the potential to be extended for analysis of a wide range of DNA repair enzyme activities. As such, these assays hold considerable promise for gaining new mechanistic insights into how DNA repair is related to individual genetics, disease status or progression and other environmental factors and investigating whether DNA repair activities can be used a biomarker of disease risk.
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Affiliation(s)
- Eleanor Healing
- Department of Nutritional Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Clara F Charlier
- Department of Clinical and Experimental Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Lisiane B Meira
- Department of Clinical and Experimental Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK
| | - Ruan M Elliott
- Department of Nutritional Sciences, University of Surrey, Guildford, Surrey GU2 7XH, UK
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5
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Sannai M, Doneddu V, Giri V, Seeholzer S, Nicolas E, Yip SC, Bassi MR, Mancuso P, Cortellino S, Cigliano A, Lurie R, Ding H, Chernoff J, Sobol RW, Yen TJ, Bagella L, Bellacosa A. Modification of the base excision repair enzyme MBD4 by the small ubiquitin-like molecule SUMO1. DNA Repair (Amst) 2019; 82:102687. [PMID: 31476572 PMCID: PMC6785017 DOI: 10.1016/j.dnarep.2019.102687] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 07/21/2019] [Accepted: 08/08/2019] [Indexed: 10/26/2022]
Abstract
The base excision repair DNA N-glycosylase MBD4 (also known as MED1), an interactor of the DNA mismatch repair protein MLH1, plays a central role in the maintenance of genomic stability of CpG sites by removing thymine and uracil from G:T and G:U mismatches, respectively. MBD4 is also involved in DNA damage response and transcriptional regulation. The interaction with other proteins is likely critical for understanding MBD4 functions. To identify novel proteins that interact with MBD4, we used tandem affinity purification (TAP) from HEK-293 cells. The MBD4-TAP fusion and its co-associated proteins were purified sequentially on IgG and calmodulin affinity columns; the final eluate was shown to contain MLH1 by western blotting, and MBD4-associated proteins were identified by mass spectrometry. Bands with molecular weight higher than that expected for MBD4 (˜66 kD) yielded peptides corresponding to MBD4 itself and the small ubiquitin-like molecule-1 (SUMO1), suggesting that MBD4 is sumoylated in vivo. MBD4 sumoylation was validated by co-immunoprecipitation in HEK-293 and MCF7 cells, and by an in vitrosumoylation assay. Sequence and mutation analysis identified three main sumoylation sites: MBD4 is sumoylated preferentially on K137, with additional sumoylation at K215 and K377. Patterns of MBD4 sumoylation were altered, in a DNA damage-specific way, by the anti-metabolite 5-fluorouracil, the alkylating agent N-Methyl-N-nitrosourea and the crosslinking agent cisplatin. MCF7 extract expressing sumoylated MBD4 displays higher thymine glycosylase activity than the unmodified species. Of the 67 MBD4 missense mutations reported in The Cancer Genome Atlas, 14 (20.9%) map near sumoylation sites. These results indicate that MBD4 is sumoylated in vivo in a DNA damage-specific manner, and suggest that sumoylation serves to regulate its repair activity and could be compromised in cancer. This study expands the role played by sumoylation in fine-tuning DNA damage response and repair.
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Affiliation(s)
- Mara Sannai
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Valentina Doneddu
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA; Department of Biomedical Sciences, University of Sassari, Sassari, 07100, Italy
| | - Veda Giri
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Steven Seeholzer
- Proteomics Core, The Children's Hospital of Philadelphia, Philadelphia PA, 19104, USA
| | - Emmanuelle Nicolas
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Shu-Chin Yip
- Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Maria Rosaria Bassi
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Pietro Mancuso
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Salvatore Cortellino
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Antonio Cigliano
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Rebecca Lurie
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Hua Ding
- Proteomics Core, The Children's Hospital of Philadelphia, Philadelphia PA, 19104, USA
| | - Jonathan Chernoff
- Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Robert W Sobol
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, AL 36604, USA
| | - Timothy J Yen
- Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA
| | - Luigi Bagella
- Department of Biomedical Sciences, University of Sassari, Sassari, 07100, Italy; Sbarro Institute for Cancer Research and Molecular Medicine, Center for Biotechnology, College of Science and Technology, Temple University, Philadelphia, PA, 19122, USA
| | - Alfonso Bellacosa
- Cancer Epigenetics and Cancer Biology Programs, Fox Chase Cancer Center, Philadelphia, PA, 19111, USA.
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6
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Kaur S, Ramdzan ZM, Guiot MC, Li L, Leduy L, Ramotar D, Sabri S, Abdulkarim B, Nepveu A. CUX1 stimulates APE1 enzymatic activity and increases the resistance of glioblastoma cells to the mono-alkylating agent temozolomide. Neuro Oncol 2019; 20:484-493. [PMID: 29036362 DOI: 10.1093/neuonc/nox178] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Background Cut Like homeobox 1 (CUX1), which encodes an auxiliary factor in base excision repair, resides on 7q22.1, the most frequently and highly amplified chromosomal region in glioblastomas. The resistance of glioblastoma cells to the mono-alkylating agent temozolomide is determined to some extent by the activity of apurinic/apyrimidinic endonuclease 1 (APE1). Methods To monitor the effect of CUX1 and its CUT domains on APE1 activity, DNA repair assays were performed with purified proteins and cell extracts. CUX1 protein expression was analyzed by immunohistochemistry using a tumor microarray of 150 glioblastoma samples. The effect of CUX1 knockdown and overexpression on the resistance of glioblastoma cell lines to temozolomide was investigated. Results We show that CUT domains stimulate APE1 activity. In agreement with these findings, CUX1 knockdown causes an increase in the number of abasic sites in genomic DNA and a decrease in APE1 activity as measured in cell extracts. Conversely, ectopic CUX1 expression increases APE1 activity and lowers the number of abasic sites. Having established that CUX1 is expressed at high levels in most glioblastomas, we next show that the resistance of glioblastoma cells to temozolomide and to a combined treatment of temozolomide and ionizing radiation is reduced following CUX1 knockdown, but increased by overexpression of CUX1 or a short protein containing only 2 CUT domains, which is active in DNA repair but devoid of transcriptional activity. Conclusion These findings indicate that CUX1 expression level impacts on the response of glioblastoma cells to treatment and identifies the CUT domains as potential therapeutic targets.
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Affiliation(s)
- Simran Kaur
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada.,Departments of Biochemistry, McGill University, Montreal, Quebec, Canada
| | - Zubaidah M Ramdzan
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada
| | - Marie-Christine Guiot
- Pathology, McGill University, Montreal, Quebec, Canada.,Departments of Pathology, Neurology, and Neurosurgery, Montreal Neurological Institute and Hospital, Montreal, Quebec, Canada
| | - Li Li
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada
| | - Lam Leduy
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada
| | - Dindial Ramotar
- Maisonneuve-Rosemont Hospital, Research Center, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada
| | - Siham Sabri
- Oncology, McGill University, Montreal, Quebec, Canada
| | | | - Alain Nepveu
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, Canada.,Departments of Biochemistry, McGill University, Montreal, Quebec, Canada.,Oncology, McGill University, Montreal, Quebec, Canada
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7
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Thymine DNA glycosylase as a novel target for melanoma. Oncogene 2019; 38:3710-3728. [PMID: 30674989 PMCID: PMC6563616 DOI: 10.1038/s41388-018-0640-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 11/08/2018] [Accepted: 12/04/2018] [Indexed: 12/27/2022]
Abstract
Melanoma is an aggressive neoplasm with increasing incidence that is classified by the NCI as a recalcitrant cancer, i.e., a cancer with poor prognosis, lacking progress in diagnosis and treatment. In addition to conventional therapy, melanoma treatment is currently based on targeting the BRAF/MEK/ERK signaling pathway and immune checkpoints. As drug resistance remains a major obstacle to treatment success, advanced therapeutic approaches based on novel targets are still urgently needed. We reasoned that the base excision repair enzyme thymine DNA glycosylase (TDG) could be such a target for its dual role in safeguarding the genome and the epigenome, by performing the last of the multiple steps in DNA demethylation. Here we show that TDG knockdown in melanoma cell lines causes cell cycle arrest, senescence, and death by mitotic alterations; alters the transcriptome and methylome; and impairs xenograft tumor formation. Importantly, untransformed melanocytes are minimally affected by TDG knockdown, and adult mice with conditional knockout of Tdg are viable. Candidate TDG inhibitors, identified through a high-throughput fluorescence-based screen, reduced viability and clonogenic capacity of melanoma cell lines and increased cellular levels of 5-carboxylcytosine, the last intermediate in DNA demethylation, indicating successful on-target activity. These findings suggest that TDG may provide critical functions specific to cancer cells that make it a highly suitable anti-melanoma drug target. By potentially disrupting both DNA repair and the epigenetic state, targeting TDG may represent a completely new approach to melanoma therapy.
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8
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Thanasupawat T, Glogowska A, Burg M, Krcek J, Beiko J, Pitz M, Zhang G, Hombach‐Klonisch S, Klonisch T. C1q/TNF-related peptide 8 (CTRP8) promotes temozolomide resistance in human glioblastoma. Mol Oncol 2018; 12:1464-1479. [PMID: 29949238 PMCID: PMC6120254 DOI: 10.1002/1878-0261.12349] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 06/09/2018] [Accepted: 06/10/2018] [Indexed: 02/05/2023] Open
Abstract
The C1q/TNF-related peptide 8 (CTRP8) has recently emerged as a novel ligand of the G protein-coupled receptor RXFP1 in the fatal brain tumor glioblastoma (GBM). We previously demonstrated that the CTRP8-RXFP1 ligand-receptor system promotes motility and matrix invasion of patient GBM and U87 MG cells by specific phosphorylation of PI3 kinase and protein kinase C. Here, we demonstrate a novel role for CTRP8 in protecting human GBM cells against the DNA alkylating damage of temozolomide (TMZ), the standard chemotherapy drug used to treat GBM. This DNA protective role of CTRP8 required a functional RXFP1-STAT3 signaling cascade in GBM cells. We identified N-methylpurine DNA glycosylase (MPG), a monofunctional glycosylase that initiates base excision repair pathway by generating an apurinic/apyrimidinic (AP) site, as a new CTRP8-RXFP1-STAT3 target in GBM. Upon TMZ exposure, treatment with CTRP8 reduced the formation of AP sites and double-strand DNA breaks in GBM cells. This CTRP8 effect was independent of cellular MGMT levels and was associated with decreased caspase 3/7 activity and increased survival of human GBM. CTRP8-induced RXFP1 activation caused an increase in cellular protein levels of the anti-apoptotic Bcl members and STAT3 targets Bcl-2 and Bcl-XL in human GBM. Collectively, our results demonstrate a novel multipronged and clinically relevant mechanism by which the CTRP8-RXFP1 ligand-receptor system exerts a DNA protective function against TMZ chemotherapeutic stress in GBM. This CTRP8-RXFP1-STAT3 axis is a novel determinant of TMZ responsiveness/chemoresistance and an emerging new drug target for improved treatment of human GBM.
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Affiliation(s)
- Thatchawan Thanasupawat
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Aleksandra Glogowska
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Maxwell Burg
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Jerry Krcek
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
- Department of SurgeryFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Jason Beiko
- Department of SurgeryFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Marshall Pitz
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
- Department of Internal MedicineFaculty of MedicineUniversity of ManitobaWinnipegCanada
- Research Institute in Oncology and Hematology (RIOH)CancerCare ManitobaWinnipegCanada
| | - Guo‐Jun Zhang
- ChangJiang Scholar's LaboratoryShantou University Medical CollegeChina
| | - Sabine Hombach‐Klonisch
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
| | - Thomas Klonisch
- Department of Human Anatomy and Cell ScienceFaculty of MedicineUniversity of ManitobaWinnipegCanada
- Department of SurgeryFaculty of MedicineUniversity of ManitobaWinnipegCanada
- Research Institute in Oncology and Hematology (RIOH)CancerCare ManitobaWinnipegCanada
- Department of Medical Microbiology & Infectious DiseasesFaculty of MedicineUniversity of ManitobaWinnipegCanada
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9
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Li J, Svilar D, McClellan S, Kim JH, Ahn EYE, Vens C, Wilson DM, Sobol RW. DNA Repair Molecular Beacon assay: a platform for real-time functional analysis of cellular DNA repair capacity. Oncotarget 2018; 9:31719-31743. [PMID: 30167090 PMCID: PMC6114979 DOI: 10.18632/oncotarget.25859] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/12/2018] [Indexed: 12/15/2022] Open
Abstract
Numerous studies have shown that select DNA repair enzyme activities impact response and/or toxicity of genotoxins, suggesting a requirement for enzyme functional analyses to bolster precision medicine or prevention. To address this need, we developed a DNA Repair Molecular Beacon (DRMB) platform that rapidly measures DNA repair enzyme activity in real-time. The DRMB assay is applicable for discovery of DNA repair enzyme inhibitors, for the quantification of enzyme rates and is sufficiently sensitive to differentiate cellular enzymatic activity that stems from variation in expression or effects of amino acid substitutions. We show activity measures of several different base excision repair (BER) enzymes, including proteins with tumor-identified point mutations, revealing lesion-, lesion-context- and cell-type-specific repair dependence; suggesting application for DNA repair capacity analysis of tumors. DRMB measurements using lysates from isogenic control and APE1-deficient human cells suggests the major mechanism of base lesion removal by most DNA glycosylases may be mono-functional base hydrolysis. In addition, development of a microbead-conjugated DRMB assay amenable to flow cytometric analysis further advances its application. Our studies establish an analytical platform capable of evaluating the enzyme activity of select DNA repair proteins in an effort to design and guide inhibitor development and precision cancer therapy options.
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Affiliation(s)
- Jianfeng Li
- University of South Alabama Mitchell Cancer Institute, Mobile, AL, USA
| | - David Svilar
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Hillman Cancer Center, Pittsburgh, PA, USA
| | - Steven McClellan
- University of South Alabama Mitchell Cancer Institute, Mobile, AL, USA
| | - Jung-Hyun Kim
- University of South Alabama Mitchell Cancer Institute, Mobile, AL, USA
| | | | - Conchita Vens
- The Netherlands Cancer Institute, Division of Cell Biology, Amsterdam, The Netherlands
| | - David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, IRP, NIH Baltimore, MD, USA
| | - Robert W Sobol
- University of South Alabama Mitchell Cancer Institute, Mobile, AL, USA.,Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.,University of Pittsburgh Cancer Institute, Hillman Cancer Center, Pittsburgh, PA, USA
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10
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Papaluca A, Wagner JR, Saragovi HU, Ramotar D. UNG-1 and APN-1 are the major enzymes to efficiently repair 5-hydroxymethyluracil DNA lesions in C. elegans. Sci Rep 2018; 8:6860. [PMID: 29717169 PMCID: PMC5931555 DOI: 10.1038/s41598-018-25124-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 04/13/2018] [Indexed: 11/16/2022] Open
Abstract
In Caenorhabditis elegans, two DNA glycosylases, UNG-1 and NTH-1, and two AP endonucleases, APN-1 and EXO-3, have been characterized from the base-excision repair (BER) pathway that repairs oxidatively modified DNA bases. UNG-1 removes uracil, while NTH-1 can remove 5-hydroxymethyluracil (5-hmU), an oxidation product of thymine, as well as other lesions. Both APN-1 and EXO-3 can incise AP sites and remove 3′-blocking lesions at DNA single strand breaks, and only APN-1 possesses 3′- to 5′-exonulease and nucleotide incision repair activities. We used C. elegans mutants to study the role of the BER pathway in processing 5-hmU. We observe that ung-1 mutants exhibited a decrease in brood size and lifespan, and an elevated level of germ cell apoptosis when challenged with 5-hmU. These phenotypes were exacerbated by RNAi downregulation of apn-1 in the ung-1 mutant. The nth-1 or exo-3 mutants displayed wild type phenotypes towards 5-hmU. We show that partially purified UNG-1 can act on 5-hmU lesion in vitro. We propose that UNG-1 removes 5-hmU incorporated into the genome and the resulting AP site is cleaved by APN-1 or EXO-3. In the absence of UNG-1, the 5-hmU is removed by NTH-1 creating a genotoxic 3′-blocking lesion that requires the action of APN-1.
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Affiliation(s)
- Arturo Papaluca
- Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Department of Medicine, 5415 Boul. de l'Assomption, Montréal, Québec, H1T2M4, Canada.,Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Department of Pharmacology and Therapeutics, McGill University, Department of Pharmacology and Therapeutics, 3755 Chemin de la Côte Sainte-Catherine, Québec, Montréal, H3T1E2, Canada
| | - J Richard Wagner
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12 Avenue Nord, Sherbrooke, Québec, J1H5N4, Canada
| | - H Uri Saragovi
- Lady Davis Institute for Medical Research, Jewish General Hospital, McGill University, Department of Pharmacology and Therapeutics, McGill University, Department of Pharmacology and Therapeutics, 3755 Chemin de la Côte Sainte-Catherine, Québec, Montréal, H3T1E2, Canada
| | - Dindial Ramotar
- Maisonneuve-Rosemont Hospital, Research Center, Université de Montréal, Department of Medicine, 5415 Boul. de l'Assomption, Montréal, Québec, H1T2M4, Canada.
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11
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Development of a Cell-Based Assay for Measuring Base Excision Repair Responses. Sci Rep 2017; 7:13007. [PMID: 29021553 PMCID: PMC5636817 DOI: 10.1038/s41598-017-12963-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 09/18/2017] [Indexed: 12/24/2022] Open
Abstract
Base excision repair (BER) is the predominant pathway for coping with most forms of hydrolytic, oxidative or alkylative DNA damage. Measuring BER capacity in living cells is valuable for both basic science applications and epidemiological studies, since deficiencies in this pathway have been associated with cancer susceptibility and other adverse health outcomes. At present, there is an ongoing effort to develop methods to effectively quantify the rate of BER as a whole. We present a variation of a previously described “Oligonucleotide Retrieval Assay” designed to measure DNA excision repair that is capable of quantifying the rate of repair of thymine glycol in a variety of human cells with a high degree of sensitivity.
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12
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Ramdzan ZM, Ginjala V, Pinder JB, Chung D, Donovan CM, Kaur S, Leduy L, Dellaire G, Ganesan S, Nepveu A. The DNA repair function of CUX1 contributes to radioresistance. Oncotarget 2017; 8:19021-19038. [PMID: 28147323 PMCID: PMC5386666 DOI: 10.18632/oncotarget.14875] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 01/19/2017] [Indexed: 01/19/2023] Open
Abstract
Ionizing radiation generates a broad spectrum of oxidative DNA lesions, including oxidized base products, abasic sites, single-strand breaks and double-strand breaks. The CUX1 protein was recently shown to function as an auxiliary factor that stimulates enzymatic activities of OGG1 through its CUT domains. In the present study, we investigated the requirement for CUX1 and OGG1 in the resistance to radiation. Cancer cell survival following ionizing radiation is reduced by CUX1 knockdown and increased by higher CUX1 expression. However, CUX1 knockdown is sufficient by itself to reduce viability in many cancer cell lines that exhibit high levels of reactive oxygen species (ROS). Consequently, clonogenic results expressed relative to that of non-irradiated cells indicate that CUX1 knockdown confers no or modest radiosensitivity to cancer cells with high ROS. A recombinant protein containing only two CUT domains is sufficient for rapid recruitment to DNA damage, acceleration of DNA repair and increased survival following radiation. In agreement with these findings, OGG1 knockdown and treatment of cells with OGG1 inhibitors sensitize cancer cells to radiation. Together, these results validate CUX1 and more specifically the CUT domains as therapeutic targets.
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Affiliation(s)
- Zubaidah M Ramdzan
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Vasudeva Ginjala
- Department of Medicine, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey 08903, USA
| | - Jordan B Pinder
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Dudley Chung
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Caroline M Donovan
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Simran Kaur
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Lam Leduy
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada
| | - Graham Dellaire
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Shridar Ganesan
- Department of Medicine, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, New Jersey 08903, USA
| | - Alain Nepveu
- Goodman Cancer Research Centre, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Biochemistry, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Medicine, McGill University, Montreal, Quebec, H3A 1A3, Canada.,Department of Oncology, McGill University, Montreal, Quebec, H3A 1A3, Canada
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13
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Towards precision prevention: Technologies for identifying healthy individuals with high risk of disease. Mutat Res 2017; 800-802:14-28. [PMID: 28458064 DOI: 10.1016/j.mrfmmm.2017.03.007] [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: 02/27/2017] [Accepted: 03/06/2017] [Indexed: 12/20/2022]
Abstract
The rise of advanced technologies for characterizing human populations at the molecular level, from sequence to function, is shifting disease prevention paradigms toward personalized strategies. Because minimization of adverse outcomes is a key driver for treatment decisions for diseased populations, developing personalized therapy strategies represent an important dimension of both precision medicine and personalized prevention. In this commentary, we highlight recently developed enabling technologies in the field of DNA damage, DNA repair, and mutagenesis. We propose that omics approaches and functional assays can be integrated into population studies that fuse basic, translational and clinical research with commercial expertise in order to accelerate personalized prevention and treatment of cancer and other diseases linked to aberrant responses to DNA damage. This collaborative approach is generally applicable to efforts to develop data-driven, individualized prevention and treatment strategies for other diseases. We also recommend strategies for maximizing the use of biological samples for epidemiological studies, and for applying emerging technologies to clinical applications.
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14
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Bigarella CL, Li J, Rimmelé P, Liang R, Sobol RW, Ghaffari S. FOXO3 Transcription Factor Is Essential for Protecting Hematopoietic Stem and Progenitor Cells from Oxidative DNA Damage. J Biol Chem 2016; 292:3005-3015. [PMID: 27994057 DOI: 10.1074/jbc.m116.769455] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Revised: 12/16/2016] [Indexed: 12/29/2022] Open
Abstract
Accumulation of damaged DNA in hematopoietic stem cells (HSC) is associated with chromosomal abnormalities, genomic instability, and HSC aging and might promote hematological malignancies with age. Despite this, the regulatory pathways implicated in the HSC DNA damage response have not been fully elucidated. One of the sources of DNA damage is reactive oxygen species (ROS) generated by both exogenous and endogenous insults. Balancing ROS levels in HSC requires FOXO3, which is an essential transcription factor for HSC maintenance implicated in HSC aging. Elevated ROS levels result in defective Foxo3-/- HSC cycling, among many other deficiencies. Here, we show that loss of FOXO3 leads to the accumulation of DNA damage in primitive hematopoietic stem and progenitor cells (HSPC), associated specifically with reduced expression of genes implicated in the repair of oxidative DNA damage. We provide further evidence that Foxo3-/- HSPC are defective in DNA damage repair. Specifically, we show that the base excision repair pathway, the main pathway utilized for the repair of oxidative DNA damage, is compromised in Foxo3-/- primitive hematopoietic cells. Treating mice in vivo with N-acetylcysteine reduces ROS levels, rescues HSC cycling defects, and partially mitigates HSPC DNA damage. These results indicate that DNA damage accrued as a result of elevated ROS in Foxo3-/- mutant HSPC is at least partially reversible. Collectively, our findings suggest that FOXO3 serves as a protector of HSC genomic stability and health.
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Affiliation(s)
- Carolina L Bigarella
- From the Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Jianfeng Li
- the Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama 36604
| | - Pauline Rimmelé
- From the Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029
| | - Raymond Liang
- From the Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029.,the Developmental and Stem Cell Biology Multidisciplinary Training Area
| | - Robert W Sobol
- the Department of Oncologic Sciences, University of South Alabama Mitchell Cancer Institute, Mobile, Alabama 36604
| | - Saghi Ghaffari
- From the Department of Cell, Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, New York 10029, .,the Developmental and Stem Cell Biology Multidisciplinary Training Area.,Department of Medicine, Division of Hematology and, Oncology.,Black Family Stem Cell Institute, and.,Tisch Cancer Institute, Icahn School of Medicine at Mount Sinai, New York, New York 10029
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15
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Kaur S, Coulombe Y, Ramdzan ZM, Leduy L, Masson JY, Nepveu A. Special AT-rich Sequence-binding Protein 1 (SATB1) Functions as an Accessory Factor in Base Excision Repair. J Biol Chem 2016; 291:22769-22780. [PMID: 27590341 DOI: 10.1074/jbc.m116.735696] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 09/01/2016] [Indexed: 01/19/2023] Open
Abstract
Base excision repair is initiated by DNA glycosylases that recognize specific altered bases. DNA glycosylases for oxidized bases carry both a glycosylase activity that removes the faulty base and an apyrimidinic/apurinic lyase activity that introduces a single-strand DNA incision. In particular, the CUT domains within the CUX1 and CUX2 proteins were recently shown to interact with the 8-oxoguanine (8-oxoG) DNA glycosylase and stimulate its enzymatic activities. SATB1, which contains two CUT domains, was originally characterized as a T cell-specific genome organizer whose aberrant overexpression in breast cancer can promote tumor progression. Here we investigated the involvement of SATB1 in DNA repair. SATB1 knockdown caused a delay in DNA repair following exposure to H2O2, an increase in OGG1-sensitive oxidized bases within genomic DNA, and a decrease in 8-oxoG cleavage activity in cell extracts. In parallel, we observed an increase in phospho-CHK1 and γ-H2AX levels and a decrease in DNA synthesis. Conversely, ectopic expression of SATB1 accelerated DNA repair and reduced the levels of oxidized bases in genomic DNA. Moreover, an enhanced GFP-SATB1 fusion protein was rapidly recruited to laser microirradiation-induced DNA damage. Using purified proteins, we showed that SATB1 interacts directly with OGG1, increases its binding to 8-oxoG-containing DNA, promotes Schiff base formation, and stimulates its glycosylase and apyrimidinic/apurinic lyase enzymatic activities. Structure/function analysis demonstrated that CUT domains, but not the homeodomain, are responsible for the stimulation of OGG1. Together, these results identify another CUT domain protein that functions both as a transcription factor and an accessory factor in base excision repair.
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Affiliation(s)
- Simran Kaur
- From the Goodman Cancer Research Centre and.,Departments of Biochemistry
| | - Yan Coulombe
- the Genome Stability Laboratory, CHU de Québec Research Center, Québec City, Québec G1R 2J6, Canada, and.,the Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, Québec G1V 0A6, Canada
| | | | - Lam Leduy
- From the Goodman Cancer Research Centre and
| | - Jean-Yves Masson
- the Genome Stability Laboratory, CHU de Québec Research Center, Québec City, Québec G1R 2J6, Canada, and.,the Department of Molecular Biology, Medical Biochemistry, and Pathology, Laval University Cancer Research Center, Québec City, Québec G1V 0A6, Canada
| | - Alain Nepveu
- From the Goodman Cancer Research Centre and .,Departments of Biochemistry.,Oncology, and.,Medicine, McGill University, Montreal, Quebec H3A 1A3, Canada
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16
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Brenerman BM, Illuzzi JL, Wilson DM. Base excision repair capacity in informing healthspan. Carcinogenesis 2014; 35:2643-52. [PMID: 25355293 PMCID: PMC4247524 DOI: 10.1093/carcin/bgu225] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/22/2014] [Accepted: 10/24/2014] [Indexed: 12/21/2022] Open
Abstract
Base excision repair (BER) is a frontline defense mechanism for dealing with many common forms of endogenous DNA damage, several of which can drive mutagenic or cell death outcomes. The pathway engages proteins such as glycosylases, abasic endonucleases, polymerases and ligases to remove substrate modifications from DNA and restore the genome back to its original state. Inherited mutations in genes related to BER can give rise to disorders involving cancer, immunodeficiency and neurodegeneration. Studies employing genetically defined heterozygous (haploinsufficient) mouse models indicate that partial reduction in BER capacity can increase vulnerability to both spontaneous and exposure-dependent pathologies. In humans, measurement of BER variation has been imperfect to this point, yet tools to assess BER in epidemiological surveys are steadily evolving. We provide herein an overview of the BER pathway and discuss the current efforts toward defining the relationship of BER defects with disease susceptibility.
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Affiliation(s)
- Boris M Brenerman
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - Jennifer L Illuzzi
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
| | - David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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17
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Wang H, Wang X, Chen G, Zhang X, Tang X, Park D, Cucinotta FA, Yu DS, Deng X, Dynan WS, Doetsch PW, Wang Y. Distinct roles of Ape1 protein, an enzyme involved in DNA repair, in high or low linear energy transfer ionizing radiation-induced cell killing. J Biol Chem 2014; 289:30635-30644. [PMID: 25210033 DOI: 10.1074/jbc.m114.604959] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
High linear energy transfer (LET) radiation from space heavy charged particles or a heavier ion radiotherapy machine kills more cells than low LET radiation, mainly because high LET radiation-induced DNA damage is more difficult to repair. Relative biological effectiveness (RBE) is the ratio of the effects generated by high LET radiation to low LET radiation. Previously, our group and others demonstrated that the cell-killing RBE is involved in the interference of high LET radiation with non-homologous end joining but not homologous recombination repair. This effect is attributable, in part, to the small DNA fragments (≤40 bp) directly produced by high LET radiation, the size of which prevents Ku protein from efficiently binding to the two ends of one fragment at the same time, thereby reducing non-homologous end joining efficiency. Here we demonstrate that Ape1, an enzyme required for processing apurinic/apyrimidinic (known as abasic) sites, is also involved in the generation of small DNA fragments during the repair of high LET radiation-induced base damage, which contributes to the higher RBE of high LET radiation-induced cell killing. This discovery opens a new direction to develop approaches for either protecting astronauts from exposure to space radiation or benefiting cancer patients by sensitizing tumor cells to high LET radiotherapy.
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Affiliation(s)
- Hongyan Wang
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Xiang Wang
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Guangnan Chen
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Xiangming Zhang
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Xiaobing Tang
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Dongkyoo Park
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Francis A Cucinotta
- Department of Health Physics and Diagnostic Sciences, University of Nevada, Las Vegas, Nevada 89154
| | - David S Yu
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Xingming Deng
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - William S Dynan
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Paul W Doetsch
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and
| | - Ya Wang
- Department of Radiation Oncology, Emory University School of Medicine and Winship Cancer Institute of Emory University, Atlanta, Georgia 30322 and.
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18
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Deletion of individual Ku subunits in mice causes an NHEJ-independent phenotype potentially by altering apurinic/apyrimidinic site repair. PLoS One 2014; 9:e86358. [PMID: 24466051 PMCID: PMC3900520 DOI: 10.1371/journal.pone.0086358] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 12/07/2013] [Indexed: 01/25/2023] Open
Abstract
Ku70 and Ku80 form a heterodimer called Ku that forms a holoenzyme with DNA dependent-protein kinase catalytic subunit (DNA-PKCS) to repair DNA double strand breaks (DSBs) through the nonhomologous end joining (NHEJ) pathway. As expected mutating these genes in mice caused a similar DSB repair-defective phenotype. However, ku70-/- cells and ku80-/- cells also appeared to have a defect in base excision repair (BER). BER corrects base lesions, apurinic/apyrimidinic (AP) sites and single stand breaks (SSBs) utilizing a variety of proteins including glycosylases, AP endonuclease 1 (APE1) and DNA Polymerase β (Pol β). In addition, deleting Ku70 was not equivalent to deleting Ku80 in cells and mice. Therefore, we hypothesized that free Ku70 (not bound to Ku80) and/or free Ku80 (not bound to Ku70) possessed activity that influenced BER. To further test this hypothesis we performed two general sets of experiments. The first set showed that deleting either Ku70 or Ku80 caused an NHEJ-independent defect. We found ku80-/- mice had a shorter life span than dna-pkcs-/- mice demonstrating a phenotype that was greater than deleting the holoenzyme. We also found Ku70-deletion induced a p53 response that reduced the level of small mutations in the brain suggesting defective BER. We further confirmed that Ku80-deletion impaired BER via a mechanism that was not epistatic to Pol β. The second set of experiments showed that free Ku70 and free Ku80 could influence BER. We observed that deletion of either Ku70 or Ku80, but not both, increased sensitivity of cells to CRT0044876 (CRT), an agent that interferes with APE1. In addition, free Ku70 and free Ku80 bound to AP sites and in the case of Ku70 inhibited APE1 activity. These observations support a novel role for free Ku70 and free Ku80 in altering BER.
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19
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Eldin P, Chazal N, Fenard D, Bernard E, Guichou JF, Briant L. Vpr expression abolishes the capacity of HIV-1 infected cells to repair uracilated DNA. Nucleic Acids Res 2013; 42:1698-710. [PMID: 24178031 PMCID: PMC3919559 DOI: 10.1093/nar/gkt974] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The human immunodeficiency virus type 1 (HIV-1) Vpr protein binds to the cellular uracil–DNA glycosylase UNG2 and induces its degradation through the assembly with the DDB1-CUL4 ubiquitin ligase complex. This interaction counteracts the antiviral activity exerted by UNG2 on HIV-1 gene transcription, as previously reported by us. In this work, we show that Vpr expression in the context of HIV-1 infection markedly decreases UNG2 expression in transformed or primary CD4+ T lymphocytes. We demonstrate for the first time that Vpr-UNG2 interaction significantly impairs the uracil excision activity of infected cells. The loss of uracil excision activity coincides with a significant accumulation of uracilated bases in the genome of infected cells without changes in cell division. Although UNG2 expression and uracil–DNA glycosylase activity are recovered after the peak of retroviral replication, the mutagenic effect of transient DNA uracilation in cycling cells should be taken into account. Therefore, the possible consequences of Vpr-mediated temporary depletion of endogenous nuclear UNG2 and subsequent alteration of the genomic integrity of infected cells need to be evaluated in the physiopathogenesis of HIV infection.
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Affiliation(s)
- Patrick Eldin
- Centre d'étude d'agents Pathogènes et Biotechnologies pour la Santé (CPBS) - UMR 5236-CNRS - Université Montpellier 1 and 2, Montpellier, France and Centre de Biochimie Structurale, INSERM U1054, CNRS UMR5048, Université Montpellier 1 and 2, Montpellier, France
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20
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Marcussen LB, Jepsen ML, Kristoffersen EL, Franch O, Proszek J, Ho YP, Stougaard M, Knudsen BR. DNA-based sensor for real-time measurement of the enzymatic activity of human topoisomerase I. SENSORS 2013; 13:4017-28. [PMID: 23529147 PMCID: PMC3673067 DOI: 10.3390/s130404017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2013] [Revised: 02/16/2013] [Accepted: 03/19/2013] [Indexed: 11/28/2022]
Abstract
Sensors capable of quantitative real-time measurements may present the easiest and most accurate way to study enzyme activities. Here we present a novel DNA-based sensor for specific and quantitative real-time measurement of the enzymatic activity of the essential human enzyme, topoisomerase I. The basic design of the sensor relies on two DNA strands that hybridize to form a hairpin structure with a fluorophore-quencher pair. The quencher moiety is released from the sensor upon reaction with human topoisomerase I thus enabling real-time optical measurement of enzymatic activity. The sensor is specific for topoisomerase I even in raw cell extracts and presents a simple mean of following enzyme kinetics using standard laboratory equipment such as a qPCR machine or fluorimeter. Human topoisomerase I is a well-known target for the clinically used anti-cancer drugs of the camptothecin family. The cytotoxic effect of camptothecins correlates directly with the intracellular topoisomerase I activity. We therefore envision that the presented sensor may find use for the prediction of cellular drug response. Moreover, inhibition of topoisomerase I by camptothecin is readily detectable using the presented DNA sensor, suggesting a potential application of the sensor for first line screening for potential topoisomerase I targeting anti-cancer drugs.
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Affiliation(s)
- Lærke Bay Marcussen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark; E-Mails: (L.B.M.); (M.L.J.); (E.L.K.); (O.F.)
- Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark; E-Mail:
| | - Morten Leth Jepsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark; E-Mails: (L.B.M.); (M.L.J.); (E.L.K.); (O.F.)
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
| | - Emil Laust Kristoffersen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark; E-Mails: (L.B.M.); (M.L.J.); (E.L.K.); (O.F.)
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
| | - Oskar Franch
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark; E-Mails: (L.B.M.); (M.L.J.); (E.L.K.); (O.F.)
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
| | - Joanna Proszek
- Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark; E-Mail:
| | - Yi-Ping Ho
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
| | - Magnus Stougaard
- Department of Pathology, Aarhus University Hospital, Aarhus C 8000, Denmark; E-Mail:
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (M.S.); (B.R.K.)
| | - Birgitta Ruth Knudsen
- Department of Molecular Biology and Genetics, Aarhus University, Aarhus C 8000, Denmark; E-Mails: (L.B.M.); (M.L.J.); (E.L.K.); (O.F.)
- Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus C 8000, Denmark; E-Mail:
- Authors to whom correspondence should be addressed; E-Mails: (M.S.); (B.R.K.)
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21
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Iyer P, Srinivasan A, Singh SK, Mascara GP, Zayitova S, Sidone B, Fouquerel E, Svilar D, Sobol RW, Bobola MS, Silber JR, Gold B. Synthesis and characterization of DNA minor groove binding alkylating agents. Chem Res Toxicol 2013; 26:156-68. [PMID: 23234400 PMCID: PMC3618862 DOI: 10.1021/tx300437x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Derivatives of methyl 3-(1-methyl-5-(1-methyl-5-(propylcarbamoyl)-1H-pyrrol-3-ylcarbamoyl)-1H-pyrrol-3-ylamino)-3-oxopropane-1-sulfonate (1), a peptide-based DNA minor groove binding methylating agent, were synthesized and characterized. In all cases, the N-terminus was appended with an O-methyl sulfonate ester, while the C-terminus group was varied with nonpolar and polar side chains. In addition, the number of pyrrole rings was varied from 2 (dipeptide) to 3 (tripeptide). The ability of the different analogues to efficiently generate N3-methyladenine was demonstrated as was their selectivity for minor groove (N3-methyladenine) versus major groove (N7-methylguanine) methylation. Induced circular dichroism studies were used to measure the DNA equilibrium binding properties of the stable sulfone analogues; the tripeptide binds with affinity that is >10-fold higher than that of the dipeptide. The toxicities of the compounds were evaluated in alkA/tag glycosylase mutant E. coli and in human WT glioma cells and in cells overexpressing and under-expressing N-methylpurine-DNA glycosylase, which excises N3-methyladenine from DNA. The results show that equilibrium binding correlates with the levels of N3-methyladenine produced and cellular toxicity. The toxicity of 1 was inversely related to the expression of MPG in both the bacterial and mammalian cell lines. The enhanced toxicity parallels the reduced activation of PARP and the diminished rate of formation of aldehyde reactive sites observed in the MPG knockdown cells. It is proposed that unrepaired N3-methyladenine is toxic due to its ability to directly block DNA polymerization.
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Affiliation(s)
- Prema Iyer
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Ajay Srinivasan
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Sreelekha K. Singh
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Gerard P. Mascara
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Sevara Zayitova
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Brian Sidone
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
| | - Elise Fouquerel
- University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh PA 15232
| | - David Svilar
- University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh PA 15232
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
| | - Robert W. Sobol
- University of Pittsburgh Cancer Institute, University of Pittsburgh, Pittsburgh PA 15232
- Department of Pharmacology & Chemical Biology, University of Pittsburgh, Pittsburgh, PA 15261
- Department of Human Genetics, University of Pittsburgh 15213
| | - Michael S. Bobola
- Department of Neurological Surgery, University of Washington, Seattle, WA 98105
| | - John R. Silber
- Department of Neurological Surgery, University of Washington, Seattle, WA 98105
| | - Barry Gold
- Department of Pharmaceutical Sciences, University of Pittsburgh, Pittsburgh, PA 15261
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22
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Svilar D, Dyavaiah M, Brown AR, Tang JB, Li J, McDonald PR, Shun TY, Braganza A, Wang XH, Maniar S, St Croix CM, Lazo JS, Pollack IF, Begley TJ, Sobol RW. Alkylation sensitivity screens reveal a conserved cross-species functionome. Mol Cancer Res 2012; 10:1580-96. [PMID: 23038810 DOI: 10.1158/1541-7786.mcr-12-0168] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
To identify genes that contribute to chemotherapy resistance in glioblastoma, we conducted a synthetic lethal screen in a chemotherapy-resistant glioblastoma-derived cell line with the clinical alkylator temozolomide (TMZ) and an siRNA library tailored toward "druggable" targets. Select DNA repair genes in the screen were validated independently, confirming the DNA glycosylases uracil-DNA glycosylase (UNG) and A/G-specific adenine DNA glycosylase (MYH) as well as methylpurine-DNA glycosylase (MPG) to be involved in the response to high dose TMZ. The involvement of UNG and MYH is likely the result of a TMZ-induced burst of reactive oxygen species. We then compared the human TMZ sensitizing genes identified in our screen with those previously identified from alkylator screens conducted in Escherichia coli and Saccharomyces cerevisiae. The conserved biologic processes across all three species compose an alkylation functionome that includes many novel proteins not previously thought to impact alkylator resistance. This high-throughput screen, validation and cross-species analysis was then followed by a mechanistic analysis of two essential nodes: base excision repair (BER) DNA glycosylases (UNG, human and mag1, S. cerevisiae) and protein modification systems, including UBE3B and ICMT in human cells or pby1, lip22, stp22 and aim22 in S. cerevisiae. The conserved processes of BER and protein modification were dual targeted and yielded additive sensitization to alkylators in S. cerevisiae. In contrast, dual targeting of BER and protein modification genes in human cells did not increase sensitivity, suggesting an epistatic relationship. Importantly, these studies provide potential new targets to overcome alkylating agent resistance.
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Affiliation(s)
- David Svilar
- Departments of Pharmacology& Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213-1863, USA
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