1
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Liu HL, Nan H, Zhao WW, Wan XB, Fan XJ. Phase separation in DNA double-strand break response. Nucleus 2024; 15:2296243. [PMID: 38146123 PMCID: PMC10761171 DOI: 10.1080/19491034.2023.2296243] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 12/12/2023] [Indexed: 12/27/2023] Open
Abstract
DNA double-strand break (DSB) is the most dangerous type of DNA damage, which may lead to cell death or oncogenic mutations. Homologous recombination (HR) and nonhomologous end-joining (NHEJ) are two typical DSB repair mechanisms. Recently, many studies have revealed that liquid-liquid phase separation (LLPS) plays a pivotal role in DSB repair and response. Through LLPS, the crucial biomolecules are quickly recruited to damaged sites with a high concentration to ensure DNA repair is conducted quickly and efficiently, which facilitates DSB repair factors activating downstream proteins or transmitting signals. In addition, the dysregulation of the DSB repair factor's phase separation has been reported to promote the development of a variety of diseases. This review not only provides a comprehensive overview of the emerging roles of LLPS in the repair of DSB but also sheds light on the regulatory patterns of phase separation in relation to the DNA damage response (DDR).
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Affiliation(s)
- Huan-Lei Liu
- Henan Provincial Key Laboratory of Radiation Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China
- Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, P.R. China
- College of Life Sciences, Northwest AF University, Yangling, Shaanxi, China
| | - Hao Nan
- College of Life Sciences, Northwest AF University, Yangling, Shaanxi, China
| | - Wan-Wen Zhao
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P.R. China
- Department of Radiation Oncology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P.R. China
| | - Xiang-Bo Wan
- Henan Provincial Key Laboratory of Radiation Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China
- Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, P.R. China
- Department of Radiation Oncology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P.R. China
| | - Xin-Juan Fan
- Henan Provincial Key Laboratory of Radiation Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan, P.R. China
- Academy of Medical Science, Zhengzhou University, Zhengzhou, Henan, P.R. China
- Guangdong Provincial Key Laboratory of Colorectal and Pelvic Floor Diseases, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P.R. China
- Department of Pathology, The Sixth Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, P.R. China
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2
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van de Kooij B, van der Wal FJ, Rother MB, Wiegant WW, Creixell P, Stout M, Joughin BA, Vornberger J, Altmeyer M, van Vugt MATM, Yaffe MB, van Attikum H. The Fanconi anemia core complex promotes CtIP-dependent end resection to drive homologous recombination at DNA double-strand breaks. Nat Commun 2024; 15:7076. [PMID: 39152113 PMCID: PMC11329772 DOI: 10.1038/s41467-024-51090-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 07/17/2024] [Indexed: 08/19/2024] Open
Abstract
During the repair of interstrand crosslinks (ICLs) a DNA double-strand break (DSB) is generated. The Fanconi anemia (FA) core complex, which is recruited to ICLs, promotes high-fidelity repair of this DSB by homologous recombination (HR). However, whether the FA core complex also promotes HR at ICL-independent DSBs, for example induced by ionizing irradiation or nucleases, remains controversial. Here, we identified the FA core complex members FANCL and Ube2T as HR-promoting factors in a CRISPR/Cas9-based screen. Using isogenic cell line models, we further demonstrated an HR-promoting function of FANCL and Ube2T, and of their ubiquitination substrate FANCD2. We show that FANCL and Ube2T localize at DSBs in a FANCM-dependent manner, and are required for the DSB accumulation of FANCD2. Mechanistically, we demonstrate that FANCL ubiquitin ligase activity is required for the accumulation of CtIP at DSBs, thereby promoting end resection and Rad51 loading. Together, these data demonstrate a dual genome maintenance function of the FA core complex and FANCD2 in promoting repair of both ICLs and DSBs.
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Affiliation(s)
- Bert van de Kooij
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.
| | - Fenna J van der Wal
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Magdalena B Rother
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Wouter W Wiegant
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Pau Creixell
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- CRUK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | - Merula Stout
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Brian A Joughin
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Julia Vornberger
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Marcel A T M van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands
| | - Michael B Yaffe
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Department of Surgery, Beth Israel Deaconess Medical Center, Divisions of Acute Care Surgery, Trauma, and Critical Care and Surgical Oncology, Harvard Medical School, Boston, USA.
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands.
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3
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Lokanathan Balaji S, De Bragança S, Balaguer-Pérez F, Northall S, Wilkinson OJ, Aicart-Ramos C, Seetaloo N, Sobott F, Moreno-Herrero F, Dillingham MS. DNA binding and bridging by human CtIP in the healthy and diseased states. Nucleic Acids Res 2024; 52:8303-8319. [PMID: 38922686 DOI: 10.1093/nar/gkae538] [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: 01/10/2024] [Revised: 06/05/2024] [Accepted: 06/13/2024] [Indexed: 06/28/2024] Open
Abstract
The human DNA repair factor CtIP helps to initiate the resection of double-stranded DNA breaks for repair by homologous recombination, in part through its ability to bind and bridge DNA molecules. However, CtIP is a natively disordered protein that bears no apparent similarity to other DNA-binding proteins and so the structural basis for these activities remains unclear. In this work, we have used bulk DNA binding, single molecule tracking, and DNA bridging assays to study wild-type and variant CtIP proteins to better define the DNA binding domains and the effects of mutations associated with inherited human disease. Our work identifies a monomeric DNA-binding domain in the C-terminal region of CtIP. CtIP binds non-specifically to DNA and can diffuse over thousands of nucleotides. CtIP-mediated bridging of distant DNA segments is observed in single-molecule magnetic tweezers experiments. However, we show that binding alone is insufficient for DNA bridging, which also requires tetramerization via the N-terminal domain. Variant CtIP proteins associated with Seckel and Jawad syndromes display impaired DNA binding and bridging activities. The significance of these findings in the context of facilitating DNA break repair is discussed.
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Affiliation(s)
- Shreya Lokanathan Balaji
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Sara De Bragança
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Francisco Balaguer-Pérez
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Sarah Northall
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Oliver John Wilkinson
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
| | - Clara Aicart-Ramos
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Neeleema Seetaloo
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Fernando Moreno-Herrero
- Department of Macromolecular Structures, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, 28049, Spain
| | - Mark Simon Dillingham
- DNA:Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK
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4
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Osborne HC, Foster BM, Al-Hazmi H, Meyer S, Larrosa I, Schmidt CK. Small-Molecule Inhibition of CBX4/7 Hypersensitises Homologous Recombination-Impaired Cancer to Radiation by Compromising CtIP-Mediated DNA End Resection. Cancers (Basel) 2024; 16:2155. [PMID: 38893273 PMCID: PMC11172190 DOI: 10.3390/cancers16112155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2024] [Revised: 06/03/2024] [Accepted: 06/04/2024] [Indexed: 06/21/2024] Open
Abstract
The therapeutic targeting of DNA repair pathways is an emerging concept in cancer treatment. Compounds that target specific DNA repair processes, such as those mending DNA double-strand breaks (DSBs), are therefore of therapeutic interest. UNC3866 is a small molecule that targets CBX4, a chromobox protein, and a SUMO E3 ligase. As a key modulator of DNA end resection-a prerequisite for DSB repair by homologous recombination (HR)-CBX4 promotes the functions of the DNA resection factor CtIP. Here, we show that treatment with UNC3866 markedly sensitises HR-deficient, NHEJ-hyperactive cancer cells to ionising radiation (IR), while it is non-toxic in selected HR-proficient cells. Consistent with UNC3866 targeting CtIP functions, it inhibits end-resection-dependent DNA repair including HR, alternative end joining (alt-EJ), and single-strand annealing (SSA). These findings raise the possibility that the UNC3866-mediated inhibition of end resection processes we define highlights a distinct vulnerability for the selective killing of HR-ineffective cancers.
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Affiliation(s)
- Hugh C. Osborne
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health (FBMH), University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK; (H.C.O.); (B.M.F.); (H.A.-H.); (S.M.)
| | - Benjamin M. Foster
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health (FBMH), University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK; (H.C.O.); (B.M.F.); (H.A.-H.); (S.M.)
| | - Hazim Al-Hazmi
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health (FBMH), University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK; (H.C.O.); (B.M.F.); (H.A.-H.); (S.M.)
| | - Stefan Meyer
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health (FBMH), University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK; (H.C.O.); (B.M.F.); (H.A.-H.); (S.M.)
- Department of Paediatric and Adolescent Oncology, Royal Manchester Children’s Hospital, Manchester M13 9WL, UK
- Department of Adolescent Oncology, The Christie NHS Foundation Trust, Wilmslow Road, Manchester M20 4BX, UK
| | - Igor Larrosa
- Department of Chemistry, University of Manchester, Chemistry Building, Oxford Road, Manchester M13 9PL, UK;
| | - Christine K. Schmidt
- Manchester Cancer Research Centre (MCRC), Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health (FBMH), University of Manchester, 555 Wilmslow Road, Manchester M20 4GJ, UK; (H.C.O.); (B.M.F.); (H.A.-H.); (S.M.)
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5
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Zhao Y, Hou K, Li Y, Hao S, Liu Y, Na Y, Li C, Cui J, Xu X, Wu X, Wang H. Human HELQ regulates DNA end resection at DNA double-strand breaks and stalled replication forks. Nucleic Acids Res 2023; 51:12207-12223. [PMID: 37897354 PMCID: PMC10711563 DOI: 10.1093/nar/gkad940] [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: 07/31/2023] [Revised: 09/15/2023] [Accepted: 10/11/2023] [Indexed: 10/30/2023] Open
Abstract
Following a DNA double strand break (DSB), several nucleases and helicases coordinate to generate single-stranded DNA (ssDNA) with 3' free ends, facilitating precise DNA repair by homologous recombination (HR). The same nucleases can act on stalled replication forks, promoting nascent DNA degradation and fork instability. Interestingly, some HR factors, such as CtIP and BRCA1, have opposite regulatory effects on the two processes, promoting end resection at DSB but inhibiting the degradation of nascent DNA on stalled forks. However, the reason why nuclease actions are regulated by different mechanisms in two DNA metabolism is poorly understood. We show that human HELQ acts as a DNA end resection regulator, with opposing activities on DNA end resection at DSBs and on stalled forks as seen for other regulators. Mechanistically, HELQ helicase activity is required for EXO1-mediated DSB end resection, while ssDNA-binding capacity of HELQ is required for its recruitment to stalled forks, facilitating fork protection and preventing chromosome aberrations caused by replication stress. Here, HELQ synergizes with CtIP but not BRCA1 or BRCA2 to protect stalled forks. These findings reveal an unanticipated role of HELQ in regulating DNA end resection at DSB and stalled forks, which is important for maintaining genome stability.
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Affiliation(s)
- Yuqin Zhao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Kaiping Hou
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Youhang Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Shuailin Hao
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yu Liu
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yinan Na
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Chao Li
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Jian Cui
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Xingzhi Xu
- Guangdong Key Laboratory for Genome Stability & Disease Prevention and Carson International Cancer Center, Marshall Laboratory of Biomedical Engineering, China Shenzhen University School of Medicine, Shenzhen, Guangdong 518060, China
| | - Xiaohua Wu
- Department of Molecular Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Hailong Wang
- Beijing Key Laboratory of DNA Damage Response and College of Life Sciences, Capital Normal University, Beijing 100048, China
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6
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Zhou X, Sekino Y, Li HT, Fu G, Yang Z, Zhao S, Gujar H, Zu X, Weisenberger DJ, Gill IS, Tulpule V, D’souza A, Quinn DI, Han B, Liang G. SETD2 Deficiency Confers Sensitivity to Dual Inhibition of DNA Methylation and PARP in Kidney Cancer. Cancer Res 2023; 83:3813-3826. [PMID: 37695044 PMCID: PMC10843145 DOI: 10.1158/0008-5472.can-23-0401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/18/2023] [Accepted: 09/06/2023] [Indexed: 09/12/2023]
Abstract
SETD2 deficiency alters the epigenetic landscape by causing depletion of H3K36me3 and plays an important role in diverse forms of cancer, most notably in aggressive and metastatic clear-cell renal cell carcinomas (ccRCC). Development of an effective treatment scheme targeting SETD2-compromised cancer is urgently needed. Considering that SETD2 is involved in DNA methylation and DNA repair, a combination treatment approach using DNA hypomethylating agents (HMA) and PARP inhibitors (PARPi) could have strong antitumor activity in SETD2-deficient kidney cancer. We tested the effects of the DNA HMA 5-aza-2'-dexoxydytidine (DAC), the PARPi talazoparib (BMN-673), and both in combination in human ccRCC models with or without SETD2 deficiency. The combination treatment of DAC and BMN-673 synergistically increased cytotoxicity in vitro in SETD2-deficient ccRCC cell lines but not in SETD2-proficient cell lines. DAC and BMN-673 led to apoptotic induction, increased DNA damage, insufficient DNA damage repair, and increased genomic instability. Furthermore, the combination treatment elevated immune responses, upregulated STING, and enhanced viral mimicry by activating transposable elements. Finally, the combination effectively suppressed the growth of SETD2-deficient ccRCC in in vivo mouse models. Together, these findings indicate that combining HMA and PARPi is a promising potential therapeutic strategy for treating SETD2-compromised ccRCC. SIGNIFICANCE SETD2 deficiency creates a vulnerable epigenetic status that is targetable using a DNA hypomethylating agent and PARP inhibitor combination to suppress renal cell carcinoma, identifying a precision medicine-based approach for SETD2-compromised cancers.
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Affiliation(s)
- Xinyi Zhou
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Urology, Xiangya Hospital, Central South University, Hunan, Changsha 410008, China
| | - Yohei Sekino
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Urology, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan
| | - Hong-Tao Li
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Guanghou Fu
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
- Department of Urology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310009, China
| | - Zhi Yang
- Department of Surgery, Keck School of Medicine of USC, Los Angeles, California; Department of Surgery and Biomedical Engineering, Keck School of Medicine USC, Los Angeles, CA, USA
| | - Shuqing Zhao
- Department of Surgery, Keck School of Medicine of USC, Los Angeles, California; Department of Surgery and Biomedical Engineering, Keck School of Medicine USC, Los Angeles, CA, USA
| | - Hemant Gujar
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Xiongbing Zu
- Department of Urology, Xiangya Hospital, Central South University, Hunan, Changsha 410008, China
| | - Daniel J Weisenberger
- Department of Biochemistry and Molecular Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Inderbir S. Gill
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Varsha Tulpule
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Anishka D’souza
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - David I Quinn
- Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Bo Han
- Department of Surgery, Keck School of Medicine of USC, Los Angeles, California; Department of Surgery and Biomedical Engineering, Keck School of Medicine USC, Los Angeles, CA, USA
| | - Gangning Liang
- Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
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7
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van de Kooij B, van der Wal FJ, Rother MB, Creixell P, Stout M, Wiegant W, Joughin BA, Vornberger J, van Vugt MA, Altmeyer M, Yaffe MB, van Attikum H. The Fanconi anemia core complex promotes CtIP-dependent end-resection to drive homologous recombination at DNA double-strand breaks. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.05.556391. [PMID: 37732274 PMCID: PMC10508776 DOI: 10.1101/2023.09.05.556391] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/22/2023]
Abstract
Homologous Recombination (HR) is a high-fidelity repair mechanism of DNA Double-Strand Breaks (DSBs), which are induced by irradiation, genotoxic chemicals or physiological DNA damaging processes. DSBs are also generated as intermediates during the repair of interstrand crosslinks (ICLs). In this context, the Fanconi anemia (FA) core complex, which is effectively recruited to ICLs, promotes HR-mediated DSB-repair. However, whether the FA core complex also promotes HR at ICL-independent DSBs remains controversial. Here, we identified the FA core complex members FANCL and Ube2T as HR-promoting factors in a CRISPR/Cas9-based screen with cells carrying the DSB-repair reporter DSB-Spectrum. Using isogenic cell-line models, we validated the HR-function of FANCL and Ube2T, and demonstrated a similar function for their ubiquitination-substrate FANCD2. We further show that FANCL and Ube2T are directly recruited to DSBs and are required for the accumulation of FANCD2 at these break sites. Mechanistically, we demonstrate that FANCL ubiquitin ligase activity is required for the accumulation of the nuclease CtIP at DSBs, and consequently for optimal end-resection and Rad51 loading. CtIP overexpression rescues HR in FANCL-deficient cells, validating that FANCL primarily regulates HR by promoting CtIP recruitment. Together, these data demonstrate that the FA core complex and FANCD2 have a dual genome maintenance function by promoting repair of DSBs as well as the repair of ICLs.
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Affiliation(s)
- Bert van de Kooij
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
- Current address: Department of Medical Oncology, University Medical Center Groningen, University of Groningen, the Netherlands
| | - Fenna J. van der Wal
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Magdalena B. Rother
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Pau Creixell
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Current address: CRUK Cambridge Institute, University of Cambridge, Cambridge, United Kingdom
| | - Merula Stout
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Wouter Wiegant
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Brian A. Joughin
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Julia Vornberger
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Marcel A.T.M. van Vugt
- Department of Medical Oncology, University Medical Center Groningen, University of Groningen, the Netherlands
| | - Matthias Altmeyer
- Department of Molecular Mechanisms of Disease, University of Zurich (UZH), Zurich, Switzerland
| | - Michael B. Yaffe
- Koch Institute for Integrative Cancer Research, MIT Center for Precision Cancer Medicine, Departments of Biology and Bioengineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Surgery, Beth Israel Deaconess Medical Center, Divisions of Acute Care Surgery, Trauma, and Critical Care and Surgical Oncology, Harvard Medical School, Boston
| | - Haico van Attikum
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
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8
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Sakasai R, Matsui T, Sunatani Y, Iwabuchi K. UbcH5c-dependent activation of DNA-dependent protein kinase in response to replication-mediated DNA double-strand breaks. Biochem Biophys Res Commun 2023; 668:42-48. [PMID: 37244033 DOI: 10.1016/j.bbrc.2023.05.068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 05/29/2023]
Abstract
Camptothecin (CPT) exhibits strong cytotoxicity by inducing DNA double-strand breaks (DSBs) through DNA replication. Unlike radiation-induced DSBs, which have two DNA ends, CPT-induced DSBs are considered to have only one DNA end. However, the differences in cellular responses to one-ended and two-ended DSBs are not well understood. Our previous study showed that proteasome inhibitor treatment suppressed CPT-induced activation of DNA-PK, a factor required for non-homologous end-joining in DSB repair, suggesting that the ubiquitin-proteasome pathway is involved in DNA-PK activation in response to one-ended DSBs. To identify the ubiquitination factors required for DNA-PK activation, we screened an siRNA library against E2 ubiquitin-conjugating enzymes and identified UbcH5c. Knockdown of UbcH5c suppressed DNA-PK activation caused by CPT, but not by the radio-mimetic drug neocarzinostatin. UbcH5c-dependent DNA-PK activation occurred independent of DNA end resection. Furthermore, loss of UbcH5c reduced DNA-PK-dependent chromosomal aberrations and suppressed the activation of cell cycle checkpoint in response to CPT. These results suggest that UbcH5c regulates DNA-PK activation in response to one-ended DSBs caused by replication fork collapse. To our knowledge, this is the first report of a DSB repair-related factor that is differentially involved in the response to one- and two-ended DSBs.
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Affiliation(s)
- Ryo Sakasai
- Department of Biochemistry I, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Tadashi Matsui
- Department of Biochemistry I, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Yumi Sunatani
- Department of Biochemistry I, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan
| | - Kuniyoshi Iwabuchi
- Department of Biochemistry I, Kanazawa Medical University, Kahoku, Ishikawa, 920-0293, Japan.
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9
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Ceppi I, Cannavo E, Bret H, Camarillo R, Vivalda F, Thakur RS, Romero-Franco A, Sartori AA, Huertas P, Guérois R, Cejka P. PLK1 regulates CtIP and DNA2 interplay in long-range DNA end resection. Genes Dev 2023; 37:119-135. [PMID: 36746606 PMCID: PMC10069449 DOI: 10.1101/gad.349981.122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2022] [Accepted: 01/12/2023] [Indexed: 02/08/2023]
Abstract
DNA double-strand break (DSB) repair is initiated by DNA end resection. CtIP acts in short-range resection to stimulate MRE11-RAD50-NBS1 (MRN) to endonucleolytically cleave 5'-terminated DNA to bypass protein blocks. CtIP also promotes the DNA2 helicase-nuclease to accelerate long-range resection downstream from MRN. Here, using AlphaFold2, we identified CtIP-F728E-Y736E as a separation-of-function mutant that is still proficient in conjunction with MRN but is not able to stimulate ssDNA degradation by DNA2. Accordingly, CtIP-F728E-Y736E impairs physical interaction with DNA2. Cellular assays revealed that CtIP-F728E-Y736E cells exhibit reduced DSB-dependent chromatin-bound RPA, impaired long-range resection, and increased sensitivity to DSB-inducing drugs. Previously, CtIP was shown to be targeted by PLK1 to inhibit long-range resection, yet the underlying mechanism was unclear. We show that the DNA2-interacting region in CtIP includes the PLK1 target site at S723. The integrity of S723 in CtIP is necessary for the stimulation of DNA2, and phosphorylation of CtIP by PLK1 in vitro is consequently inhibitory, explaining why PLK1 restricts long-range resection. Our data support a model in which CDK-dependent phosphorylation of CtIP activates resection by MRN in S phase, and PLK1-mediated phosphorylation of CtIP disrupts CtIP stimulation of DNA2 to attenuate long-range resection later at G2/M.
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Affiliation(s)
- Ilaria Ceppi
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
| | - Elda Cannavo
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Hélène Bret
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Rosa Camarillo
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Francesca Vivalda
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Roshan Singh Thakur
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland
| | - Amador Romero-Franco
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zürich, Zürich 8057, Switzerland
| | - Pablo Huertas
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Sevilla 41080, Spain
- Centro Andaluz de Biología Molecular y Medicina Regenerativa (CABIMER), Universidad de Sevilla-Consejo Superior de Investigaciones Científicas-Universidad Pablo de Olavide, Sevilla 41092, Spain
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), Commissariat à l'Energie Atomique, Centre National de la Recherche Scientifique, Université Paris-Sud, Université Paris-Saclay, Gif-sur-Yvette 91190, France
| | - Petr Cejka
- Institute for Research in Biomedicine, Faculty of Biomedical Sciences, Università della Svizzera italiana (USI), Bellinzona 6500, Switzerland;
- Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
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10
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A CRISPR-Cas9 screen identifies EXO1 as a formaldehyde resistance gene. Nat Commun 2023; 14:381. [PMID: 36693839 PMCID: PMC9873647 DOI: 10.1038/s41467-023-35802-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 12/28/2022] [Indexed: 01/25/2023] Open
Abstract
Fanconi Anemia (FA) is a rare, genome instability-associated disease characterized by a deficiency in repairing DNA crosslinks, which are known to perturb several cellular processes, including DNA transcription, replication, and repair. Formaldehyde, a by-product of metabolism, is thought to drive FA by generating DNA interstrand crosslinks (ICLs) and DNA-protein crosslinks (DPCs). However, the impact of formaldehyde on global cellular pathways has not been investigated thoroughly. Herein, using a pangenomic CRISPR-Cas9 screen, we identify EXO1 as a critical regulator of formaldehyde-induced DNA lesions. We show that EXO1 knockout cell lines exhibit formaldehyde sensitivity leading to the accumulation of replicative stress, DNA double-strand breaks, and quadriradial chromosomes, a typical feature of FA. After formaldehyde exposure, EXO1 is recruited to chromatin, protects DNA replication forks from degradation, and functions in parallel with the FA pathway to promote cell survival. In vitro, EXO1-mediated exonuclease activity is proficient in removing DPCs. Collectively, we show that EXO1 limits replication stress and DNA damage to counteract formaldehyde-induced genome instability.
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11
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The Roles of EXO1 and RPA1 Polymorphisms in Prognosis of Lung Cancer Patients Treated with Platinum-Based Chemotherapy. DISEASE MARKERS 2022; 2022:3306189. [PMID: 36277983 PMCID: PMC9584701 DOI: 10.1155/2022/3306189] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Accepted: 09/29/2022] [Indexed: 12/24/2022]
Abstract
Background. Lung cancer is one of the major causes of cancer-related mortality worldwide. DNA repair and damage response contribute to genomic instability that accompanies tumor progression. In this study, we focus on evaluating association between DNA repair polymorphisms of EXO1, RPA1, and prognosis in lung cancer patients whom received platinum-based chemotherapy. Methods. 593 lung cancer patients were recruited in this study. We performed genotyping of 19 single nucleotide polymorphisms (SNPs) by Sequenom MassARRAY. Cox regression analysis was used to assess overall survival (OS) and progression-free survival (PFS) among SNP genotypes. Results. Significant differences in PFS and OS were observed in RPA1 rs5030740, EXO1 rs1776148, and rs1047840. Results showed that patients with CC genotype in rs5030740 (recessive model:
) had a better PFS. Patients with AA or/and AG genotypes in rs1776148 (additive model:
; dominant model:
) and AA genotype in rs1047840 (recessive model:
) had longer OS. We also demonstrated differences in subgroup analysis between rs5030740, rs1776148, rs1047840, and prognosis. Conclusions. Our results indicated that EXO1 rs1776148, rs1047840, and RPA1 rs5030740 were significantly associated with prognosis of lung cancer. Rs1776148, rs1047840, and rs5030740 may act as prognosis markers in lung cancer patients with platinum-based chemotherapy.
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12
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Oh W, Wu TT, Jeong SY, You HJ, Lee JH. CtIP Regulates Mitotic Spindle Assembly by Modulating the TPX2-Aurora A Signaling Axis. Cells 2022; 11:cells11182814. [PMID: 36139389 PMCID: PMC9497199 DOI: 10.3390/cells11182814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 09/07/2022] [Accepted: 09/07/2022] [Indexed: 11/16/2022] Open
Abstract
CtBP-interacting protein (CtIP) plays a critical role in controlling the homologous recombination-mediated DNA double-stranded break (DSB) repair pathway through DNA end resection, and recent studies suggest that it also plays a role in mitosis. However, the mechanism by which CtIP contributes to mitosis regulation remains elusive. Here, we show that depletion of CtIP leads to a delay in anaphase progression resulting in misaligned chromosomes, an aberrant number of centrosomes, and defects in chromosome segregation. Additionally, we demonstrate that CtIP binds and colocalizes with Targeting protein for Xklp2 (TPX2) during mitosis to regulate the recruitment of TPX2 to the spindle poles. Furthermore, depletion of CtIP resulted in both a lower concentration of Aurora A, its downstream target, and very low microtubule intensity at the spindle poles, suggesting an important role for the CtIP-TPX2-Auroa A complex in microtubule dynamics at the centrosomal spindles. Our findings reveal a novel function of CtIP in regulating spindle dynamics through interactions with TPX2 and indicate that CtIP is involved in the proper execution of the mitotic program, where deregulation may lead to chromosomal instability.
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Affiliation(s)
- Wonkyung Oh
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Ting Ting Wu
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Seo-Yeon Jeong
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Ho Jin You
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
- Department of Pharmacology, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
| | - Jung-Hee Lee
- Laboratory of Genomic Instability and Cancer Therapeutics, Cancer Mutation Research Center, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
- Department of Cellular and Molecular Medicine, School of Medicine, Chosun University, 375 Seosuk-dong, Gwangju 61452, Korea
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13
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Ali A, Xiao W, Babar ME, Bi Y. Double-Stranded Break Repair in Mammalian Cells and Precise Genome Editing. Genes (Basel) 2022; 13:genes13050737. [PMID: 35627122 PMCID: PMC9142082 DOI: 10.3390/genes13050737] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 12/16/2022] Open
Abstract
In mammalian cells, double-strand breaks (DSBs) are repaired predominantly by error-prone non-homologous end joining (NHEJ), but less prevalently by error-free template-dependent homologous recombination (HR). DSB repair pathway selection is the bedrock for genome editing. NHEJ results in random mutations when repairing DSB, while HR induces high-fidelity sequence-specific variations, but with an undesirable low efficiency. In this review, we first discuss the latest insights into the action mode of NHEJ and HR in a panoramic view. We then propose the future direction of genome editing by virtue of these advancements. We suggest that by switching NHEJ to HR, full fidelity genome editing and robust gene knock-in could be enabled. We also envision that RNA molecules could be repurposed by RNA-templated DSB repair to mediate precise genetic editing.
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Affiliation(s)
- Akhtar Ali
- Key Laboratory of Animal Embryo and Molecular Breeding of Hubei Province, Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (A.A.); (W.X.)
- Department of Biotechnology, Virtual University of Pakistan, Lahore 54000, Pakistan
| | - Wei Xiao
- Key Laboratory of Animal Embryo and Molecular Breeding of Hubei Province, Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (A.A.); (W.X.)
| | - Masroor Ellahi Babar
- The University of Agriculture Dera Ismail Khan, Dera Ismail Khan 29220, Pakistan;
| | - Yanzhen Bi
- Key Laboratory of Animal Embryo and Molecular Breeding of Hubei Province, Institute of Animal Science and Veterinary Medicine, Hubei Academy of Agricultural Sciences, Wuhan 430064, China; (A.A.); (W.X.)
- Correspondence: ; Tel.: +86-151-0714-8708
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14
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Abdisalaam S, Mukherjee S, Bhattacharya S, Kumari S, Sinha D, Ortega J, Li GM, Sadek H, Krishnan S, Asaithamby A. NBS1-CtIP-mediated DNA end resection suppresses cGAS binding to micronuclei. Nucleic Acids Res 2022; 50:2681-2699. [PMID: 35189637 PMCID: PMC8934670 DOI: 10.1093/nar/gkac079] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 01/12/2022] [Accepted: 01/25/2022] [Indexed: 01/07/2023] Open
Abstract
Cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS) is activated in cells with defective DNA damage repair and signaling (DDR) factors, but a direct role for DDR factors in regulating cGAS activation in response to micronuclear DNA is still poorly understood. Here, we provide novel evidence that Nijmegen breakage syndrome 1 (NBS1) protein, a well-studied DNA double-strand break (DSB) sensor-in coordination with Ataxia Telangiectasia Mutated (ATM), a protein kinase, and Carboxy-terminal binding protein 1 interacting protein (CtIP), a DNA end resection factor-functions as an upstream regulator that prevents cGAS from binding micronuclear DNA. When NBS1 binds to micronuclear DNA via its fork-head-associated domain, it recruits CtIP and ATM via its N- and C-terminal domains, respectively. Subsequently, ATM stabilizes NBS1's interaction with micronuclear DNA, and CtIP converts DSB ends into single-strand DNA ends; these two key events prevent cGAS from binding micronuclear DNA. Additionally, by using a cGAS tripartite system, we show that cells lacking NBS1 not only recruit cGAS to a major fraction of micronuclear DNA but also activate cGAS in response to these micronuclear DNA. Collectively, our results underscore how NBS1 and its binding partners prevent cGAS from binding micronuclear DNA, in addition to their classical functions in DDR signaling.
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Affiliation(s)
- Salim Abdisalaam
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shibani Mukherjee
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Souparno Bhattacharya
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sharda Kumari
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Debapriya Sinha
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Janice Ortega
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Guo-Min Li
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Hesham A Sadek
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sunil Krishnan
- Department of Radiation Oncology, Mayo Clinic Florida, Jacksonville, FL 32082, USA
| | - Aroumougame Asaithamby
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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15
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Hausmann M, Hildenbrand G, Pilarczyk G. Networks and Islands of Genome Nano-architecture and Their Potential Relevance for Radiation Biology : (A Hypothesis and Experimental Verification Hints). Results Probl Cell Differ 2022; 70:3-34. [PMID: 36348103 DOI: 10.1007/978-3-031-06573-6_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The cell nucleus is a complex biological system in which simultaneous reactions and functions take place to keep the cell as an individualized, specialized system running well. The cell nucleus contains chromatin packed in various degrees of density and separated in volumes of chromosome territories and subchromosomal domains. Between the chromatin, however, there is enough "free" space for floating RNA, proteins, enzymes, ATPs, ions, water molecules, etc. which are trafficking by super- and supra-diffusion to the interaction points where they are required. It seems that this trafficking works somehow automatically and drives the system perfectly. After exposure to ionizing radiation causing DNA damage from single base damage up to chromatin double-strand breaks, the whole system "cell nucleus" responds, and repair processes are starting to recover the fully functional and intact system. In molecular biology, many individual epigenetic pathways of DNA damage response or repair of single and double-strand breaks are described. How these responses are embedded into the response of the system as a whole is often out of the focus of consideration. In this article, we want to follow the hypothesis of chromatin architecture's impact on epigenetic pathways and vice versa. Based on the assumption that chromatin acts like an "aperiodic solid state within a limited volume," functionally determined networks and local topologies ("islands") can be defined that drive the appropriate repair process at a given damage site. Experimental results of investigations of the chromatin nano-architecture and DNA repair clusters obtained by means of single-molecule localization microscopy offer hints and perspectives that may contribute to verifying the hypothesis.
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Affiliation(s)
- Michael Hausmann
- Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany.
| | - Georg Hildenbrand
- Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany
| | - Götz Pilarczyk
- Kirchhoff-Institute for Physics, Heidelberg University, Heidelberg, Germany
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16
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Kong M, Greene EC. Mechanistic Insights From Single-Molecule Studies of Repair of Double Strand Breaks. Front Cell Dev Biol 2021; 9:745311. [PMID: 34869333 PMCID: PMC8636147 DOI: 10.3389/fcell.2021.745311] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/28/2021] [Indexed: 01/01/2023] Open
Abstract
DNA double strand breaks (DSBs) are among some of the most deleterious forms of DNA damage. Left unrepaired, they are detrimental to genome stability, leading to high risk of cancer. Two major mechanisms are responsible for the repair of DSBs, homologous recombination (HR) and nonhomologous end joining (NHEJ). The complex nature of both pathways, involving a myriad of protein factors functioning in a highly coordinated manner at distinct stages of repair, lend themselves to detailed mechanistic studies using the latest single-molecule techniques. In avoiding ensemble averaging effects inherent to traditional biochemical or genetic methods, single-molecule studies have painted an increasingly detailed picture for every step of the DSB repair processes.
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Affiliation(s)
| | - Eric C. Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University Irving Medical Center, New York, NY, United States
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17
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Xue C, Greene EC. DNA Repair Pathway Choices in CRISPR-Cas9-Mediated Genome Editing. Trends Genet 2021; 37:639-656. [PMID: 33896583 PMCID: PMC8187289 DOI: 10.1016/j.tig.2021.02.008] [Citation(s) in RCA: 123] [Impact Index Per Article: 41.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/25/2021] [Accepted: 02/26/2021] [Indexed: 12/14/2022]
Abstract
Many clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (Cas9)-based genome editing technologies take advantage of Cas nucleases to induce DNA double-strand breaks (DSBs) at desired locations within a genome. Further processing of the DSBs by the cellular DSB repair machinery is then necessary to introduce desired mutations, sequence insertions, or gene deletions. Thus, the accuracy and efficiency of genome editing are influenced by the cellular DSB repair pathways. DSBs are themselves highly genotoxic lesions and as such cells have evolved multiple mechanisms for their repair. These repair pathways include homologous recombination (HR), classical nonhomologous end joining (cNHEJ), microhomology-mediated end joining (MMEJ) and single-strand annealing (SSA). In this review, we briefly highlight CRISPR-Cas9 and then describe the mechanisms of DSB repair. Finally, we summarize recent findings of factors that can influence the choice of DNA repair pathway in response to Cas9-induced DSBs.
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Affiliation(s)
- Chaoyou Xue
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Eric C Greene
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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18
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Kuster A, Mozaffari NL, Wilkinson OJ, Wojtaszek JL, Zurfluh C, Przetocka S, Zyla D, von Aesch C, Dillingham MS, Williams RS, Sartori AA. A stapled peptide mimetic of the CtIP tetramerization motif interferes with double-strand break repair and replication fork protection. SCIENCE ADVANCES 2021; 7:7/8/eabc6381. [PMID: 33608267 PMCID: PMC7895427 DOI: 10.1126/sciadv.abc6381] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Cancer cells display high levels of DNA damage and replication stress, vulnerabilities that could be exploited by drugs targeting DNA repair proteins. Human CtIP promotes homology-mediated repair of DNA double-strand breaks (DSBs) and protects stalled replication forks from nucleolytic degradation, thus representing an attractive candidate for targeted cancer therapy. Here, we establish a peptide mimetic of the CtIP tetramerization motif that inhibits CtIP activity. The hydrocarbon-stapled peptide encompassing amino acid residues 18 to 28 of CtIP (SP18-28) stably binds to CtIP tetramers in vitro and facilitates their aggregation into higher-order structures. Efficient intracellular uptake of SP18-28 abrogates CtIP localization to damaged chromatin, impairs DSB repair, and triggers extensive fork degradation. Moreover, prolonged SP18-28 treatment causes hypersensitivity to DNA-damaging agents and selectively reduces the viability of BRCA1-mutated cancer cell lines. Together, our data provide a basis for the future development of CtIP-targeting compounds with the potential to treat patients with cancer.
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Affiliation(s)
- Anika Kuster
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Nour L Mozaffari
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Oliver J Wilkinson
- School of Biochemistry, University of Bristol, University Walk, Clifton BS8 1TD, Bristol, UK
| | - Jessica L Wojtaszek
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, U.S. National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Christina Zurfluh
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Sara Przetocka
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Dawid Zyla
- Institute of Molecular Biology and Biophysics, ETH-Zürich, Otto-Stern-Weg 5, CH-8093 Zürich, Switzerland
| | - Christine von Aesch
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
| | - Mark S Dillingham
- School of Biochemistry, University of Bristol, University Walk, Clifton BS8 1TD, Bristol, UK
| | - R Scott Williams
- Structural Cell Biology Group, Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, U.S. National Institutes of Health, Department of Health and Human Services, Research Triangle Park, NC 27709, USA
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
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19
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Mozaffari NL, Pagliarulo F, Sartori AA. Human CtIP: A 'double agent' in DNA repair and tumorigenesis. Semin Cell Dev Biol 2020; 113:47-56. [PMID: 32950401 DOI: 10.1016/j.semcdb.2020.09.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/20/2020] [Accepted: 09/02/2020] [Indexed: 12/14/2022]
Abstract
Human CtIP was originally identified as an interactor of the retinoblastoma protein and BRCA1, two bona fide tumour suppressors frequently mutated in cancer. CtIP is renowned for its role in the resection of DNA double-strand breaks (DSBs) during homologous recombination, a largely error-free DNA repair pathway crucial in maintaining genome integrity. However, CtIP-dependent DNA end resection is equally accountable for alternative end-joining, a mutagenic DSB repair mechanism implicated in oncogenic chromosomal translocations. In addition, CtIP contributes to transcriptional regulation of G1/S transition, DNA damage checkpoint signalling, and replication fork protection pathways. In this review, we present a perspective on the current state of knowledge regarding the tumour-suppressive and oncogenic properties of CtIP and provide an overview of their relevance for cancer development, progression, and therapy.
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Affiliation(s)
- Nour L Mozaffari
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Fabio Pagliarulo
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, Zurich, Switzerland.
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20
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Wassing IE, Esashi F. RAD51: Beyond the break. Semin Cell Dev Biol 2020; 113:38-46. [PMID: 32938550 PMCID: PMC8082279 DOI: 10.1016/j.semcdb.2020.08.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Revised: 08/14/2020] [Accepted: 08/28/2020] [Indexed: 01/30/2023]
Abstract
As the primary catalyst of homologous recombination (HR) in vertebrates, RAD51 has been extensively studied in the context of repair of double-stranded DNA breaks (DSBs). With recent advances in the understanding of RAD51 function extending beyond DSBs, the importance of RAD51 throughout DNA metabolism has become increasingly clear. Here we review the suggested roles of RAD51 beyond HR, specifically focusing on their interplay with DNA replication and the maintenance of genomic stability, in which RAD51 function emerges as a double-edged sword.
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Affiliation(s)
- Isabel E Wassing
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK
| | - Fumiko Esashi
- Sir William Dunn School of Pathology, University of Oxford, Oxford, UK.
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21
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Francica P, Mutlu M, Blomen VA, Oliveira C, Nowicka Z, Trenner A, Gerhards NM, Bouwman P, Stickel E, Hekkelman ML, Lingg L, Klebic I, van de Ven M, de Korte-Grimmerink R, Howald D, Jonkers J, Sartori AA, Fendler W, Chapman JR, Brummelkamp T, Rottenberg S. Functional Radiogenetic Profiling Implicates ERCC6L2 in Non-homologous End Joining. Cell Rep 2020; 32:108068. [PMID: 32846126 DOI: 10.1016/j.celrep.2020.108068] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 04/27/2020] [Accepted: 08/04/2020] [Indexed: 12/20/2022] Open
Abstract
Using genome-wide radiogenetic profiling, we functionally dissect vulnerabilities of cancer cells to ionizing radiation (IR). We identify ERCC6L2 as a major determinant of IR response, together with classical DNA damage response genes and members of the recently identified shieldin and CTC1-STN1-TEN1 (CST) complexes. We show that ERCC6L2 contributes to non-homologous end joining (NHEJ), and it may exert this function through interactions with SFPQ. In addition to causing radiosensitivity, ERCC6L2 loss restores DNA end resection and partially rescues homologous recombination (HR) in BRCA1-deficient cells. As a consequence, ERCC6L2 deficiency confers resistance to poly (ADP-ribose) polymerase (PARP) inhibition in tumors deficient for both BRCA1 and p53. Moreover, we show that ERCC6L2 mutations are found in human tumors and correlate with a better overall survival in patients treated with radiotherapy (RT); this finding suggests that ERCC6L2 is a predictive biomarker of RT response.
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Affiliation(s)
- Paola Francica
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Merve Mutlu
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Vincent A Blomen
- Division of Biochemistry, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Catarina Oliveira
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Zuzanna Nowicka
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, 92-215 Lodz, Poland
| | - Anika Trenner
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland
| | - Nora M Gerhards
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Peter Bouwman
- Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Division of Molecular Pathology, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Elmer Stickel
- Division of Biochemistry, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Maarten L Hekkelman
- Division of Biochemistry, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Lea Lingg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Ismar Klebic
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Marieke van de Ven
- Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Renske de Korte-Grimmerink
- Mouse Clinic for Cancer and Aging Research (MCCA), Preclinical Intervention Unit, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Denise Howald
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland
| | - Jos Jonkers
- Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Division of Molecular Pathology, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Alessandro A Sartori
- Institute of Molecular Cancer Research, University of Zurich, 8057 Zurich, Switzerland
| | - Wojciech Fendler
- Department of Biostatistics and Translational Medicine, Medical University of Lodz, 92-215 Lodz, Poland; Department of Radiation Oncology, Dana-Farber Cancer Institute, Boston, MA 02215, USA
| | - J Ross Chapman
- Medical Research Council (MRC) Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford OX3 9DS, UK
| | - Thijn Brummelkamp
- Division of Biochemistry, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Oncode Institute, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, 3012 Bern, Switzerland; Division of Molecular Pathology, the Netherlands Cancer Institute, 1066CX Amsterdam, the Netherlands; Bern Center for Precision Medicine, University of Bern, 3012 Bern, Switzerland.
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22
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Reginato G, Cejka P. The MRE11 complex: A versatile toolkit for the repair of broken DNA. DNA Repair (Amst) 2020; 91-92:102869. [PMID: 32480356 DOI: 10.1016/j.dnarep.2020.102869] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 12/13/2022]
Abstract
When DNA breaks, the ends need to be stabilized and processed to facilitate subsequent repair, which can occur by either direct but error-prone end-joining with another broken DNA molecule or a more accurate homology-directed repair by the recombination machinery. At the same time, the presence of broken DNA triggers a signaling cascade that regulates the repair events and cellular progression through the cell cycle. The MRE11 nuclease, together with RAD50 and NBS1 forms a complex termed MRN that participates in all these processes. Although MRE11 was first identified more than 20 years ago, deep insights into its mechanism of action and regulation are much more recent. Here we review how MRE11 functions within MRN, and how the complex is further regulated by CtIP and its phosphorylation in a cell cycle dependent manner. We describe how RAD50, NBS1 and CtIP convert MRE11, exhibiting per se a 3'→5' exonuclease activity, into an ensemble that instead degrades primarily the 5'-terminated strand by endonucleolytic cleavage at DNA break sites to generate 3' overhangs, as required for the initiation of homologous recombination. The unique mechanism of DNA end resection by MRN-CtIP makes it a very flexible toolkit to process DNA breaks with a variety of secondary structures and protein blocks. Such a block can also be the Ku heterodimer, and emerging evidence suggests that MRN-CtIP may often need to remove Ku from DNA ends before initiating homologous recombination. Misregulation of DNA break repair results in mutations and chromosome rearrangements that can drive cancer development. Therefore, a detailed understanding of the underlying processes is highly relevant for human health.
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Affiliation(s)
- Giordano Reginato
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Petr Cejka
- Institute for Research in Biomedicine, Università della Svizzera Italiana (USI), Faculty of Biomedical Sciences, Bellinzona, Switzerland; Department of Biology, Institute of Biochemistry, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland.
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23
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The dichotomous effects of caffeine on homologous recombination in mammalian cells. DNA Repair (Amst) 2020; 88:102805. [PMID: 32062581 DOI: 10.1016/j.dnarep.2020.102805] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 01/15/2020] [Accepted: 01/19/2020] [Indexed: 11/23/2022]
Abstract
This study was initiated to examine the effects of caffeine on the DNA damage response (DDR) and homologous recombination (HR) in mammalian cells. A 5 mM caffeine treatment caused the cell cycle to stall at G2/M and cells eventually underwent apoptosis. Caffeine exposure also induced a strong DDR along with subsequent activation of wildtype p53 protein. An unexpected observation was the caffeine-induced depletion of Rad51 (and Brca2) proteins. Consequently, caffeine-treated cells were expected to be inefficient in HR. However, a dichotomy in the HR response of cells to caffeine treatment was revealed. Caffeine treatment rendered cells significantly better at performing the nascent DNA synthesis that accompanies the early strand invasion steps of HR. Additionally, caffeine treatment increased chromatin accessibility and elevated the efficiency of illegitimate recombination. Conversely, the increase in nascent DNA synthesis did not translate into a higher number of gene targeting events. Thus, prolonged caffeine exposure stalls the cell cycle, induces a p53-mediated apoptotic response and a down-regulation of critical HR proteins, and for reasons discussed, stimulates early steps of HR, but not the formation of complete recombination products.
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24
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Yu J, Qin B, Lou Z. Ubiquitin and ubiquitin-like molecules in DNA double strand break repair. Cell Biosci 2020; 10:13. [PMID: 32071713 PMCID: PMC7014694 DOI: 10.1186/s13578-020-0380-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Accepted: 01/30/2020] [Indexed: 12/23/2022] Open
Abstract
Both environmental and endogenous factors induce various forms of DNA damage. DNA double strand break (DSB) is the most deleterious DNA lesion. The swift initiation of a complexed network of interconnected pathways to repair the DNA lesion is essential for cell survival. In the past years, the roles of ubiquitin and ubiquitin-like proteins in DNA damage response and DNA repair has been explored. These findings help us better understand the complicated mechanism of DSB signaling pathways.
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Affiliation(s)
- Jia Yu
- 1Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905 USA
| | - Bo Qin
- 1Division of Clinical Pharmacology, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, MN 55905 USA.,2Department of Oncology, Mayo Clinic, Rochester, MN 55905 USA.,3Gastrointestinal Research Unit, Mayo Clinic, Rochester, MN 55905 USA
| | - Zhenkun Lou
- 2Department of Oncology, Mayo Clinic, Rochester, MN 55905 USA
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25
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Zheng L, Meng Y, Campbell JL, Shen B. Multiple roles of DNA2 nuclease/helicase in DNA metabolism, genome stability and human diseases. Nucleic Acids Res 2020; 48:16-35. [PMID: 31754720 PMCID: PMC6943134 DOI: 10.1093/nar/gkz1101] [Citation(s) in RCA: 62] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 10/23/2019] [Accepted: 11/12/2019] [Indexed: 12/25/2022] Open
Abstract
DNA2 nuclease/helicase is a structure-specific nuclease, 5'-to-3' helicase, and DNA-dependent ATPase. It is involved in multiple DNA metabolic pathways, including Okazaki fragment maturation, replication of 'difficult-to-replicate' DNA regions, end resection, stalled replication fork processing, and mitochondrial genome maintenance. The participation of DNA2 in these different pathways is regulated by its interactions with distinct groups of DNA replication and repair proteins and by post-translational modifications. These regulatory mechanisms induce its recruitment to specific DNA replication or repair complexes, such as DNA replication and end resection machinery, and stimulate its efficient cleavage of various structures, for example, to remove RNA primers or to produce 3' overhangs at telomeres or double-strand breaks. Through these versatile activities at replication forks and DNA damage sites, DNA2 functions as both a tumor suppressor and promoter. In normal cells, it suppresses tumorigenesis by maintaining the genomic integrity. Thus, DNA2 mutations or functional deficiency may lead to cancer initiation. However, DNA2 may also function as a tumor promoter, supporting cancer cell survival by counteracting replication stress. Therefore, it may serve as an ideal target to sensitize advanced DNA2-overexpressing cancers to current chemo- and radiotherapy regimens.
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Affiliation(s)
- Li Zheng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Yuan Meng
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
| | - Judith L Campbell
- Divisions of Chemistry and Chemical Engineering and Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Binghui Shen
- Department of Cancer Genetics and Epigenetics, Beckman Research Institute of City of Hope, 1500 East Duarte Road, Duarte, CA 91010, USA
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26
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Stroik S, Kurtz K, Hendrickson EA. CtIP is essential for telomere replication. Nucleic Acids Res 2019; 47:8927-8940. [PMID: 31378812 PMCID: PMC6755089 DOI: 10.1093/nar/gkz652] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 07/08/2019] [Accepted: 07/16/2019] [Indexed: 01/10/2023] Open
Abstract
The maintenance of telomere length is critical to longevity and survival. Specifically, the failure to properly replicate, resect, and/or form appropriate telomeric structures drives telomere shortening and, in turn, genomic instability. The endonuclease CtIP is a DNA repair protein that is well-known to promote genome stability through the resection of endogenous DNA double-stranded breaks. Here, we describe a novel role for CtIP. We show that in the absence of CtIP, human telomeres shorten rapidly to non-viable lengths. This telomere dysfunction results in an accumulation of fusions, breaks, and frank telomere loss. Additionally, CtIP suppresses the generation of circular, extrachromosomal telomeric DNA. These latter structures appear to arise from arrested DNA replication forks that accumulate in the absence of CtIP. Hence, CtIP is required for faithful replication through telomeres via its roles at stalled replication tracts. Our findings demonstrate a new role for CtIP as a protector of human telomere integrity.
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Affiliation(s)
- Susanna Stroik
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Kevin Kurtz
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
| | - Eric A Hendrickson
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota Medical School, Minneapolis, MN 55455, USA
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27
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Xie Y, Liu YK, Guo ZP, Guan H, Liu XD, Xie DF, Jiang YG, Ma T, Zhou PK. RBX1 prompts degradation of EXO1 to limit the homologous recombination pathway of DNA double-strand break repair in G1 phase. Cell Death Differ 2019; 27:1383-1397. [PMID: 31562368 PMCID: PMC7205894 DOI: 10.1038/s41418-019-0424-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 09/06/2019] [Accepted: 09/12/2019] [Indexed: 01/12/2023] Open
Abstract
End resection of DNA double-strand breaks (DSBs) to form 3′ single-strand DNA (ssDNA) is critical to initiate the homologous recombination (HR) pathway of DSB repair. HR pathway is strictly limited in the G1-phase cells because of lack of homologous DNA as the templates. Exonuclease 1 (EXO1) is the key molecule responsible for 3′ ssDNA formation of DSB end resection. We revealed that EXO1 is inactivated in G1-phase cells via ubiquitination-mediated degradation, resulting from an elevated expression level of RING-box protein 1 (RBX1) in G1 phase. The increased RBX1 significantly prompted the neddylation of Cullin1 and contributed to the G1 phase-specific degradation of EXO1. Knockdown of RBX1 remarkedly attenuated the degradation of EXO1 and increased the end resection and HR activity in γ-irradiated G1-phase cells, as demonstrated by the increased formation of RPA32, BrdU, and RAD51 foci. And EXO1 depletion mitigated DNA repair defects due to RBX1 reduction. Moreover, increased autophosphorylation of DNA-PKcs at S2056 was found to be responsible for the higher expression level of the RBX1 in the G1 phase. Inactivation of DNA-PKcs decreased RBX1 expression, and simultaneously increased EXO1 expression and DSB end resection in G1-phase cells. This study demonstrates a new mechanism for restraining the HR pathway of DNA DSB repair in G1 phase via RBX1-prompted inactivation of EXO1.
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Affiliation(s)
- Ying Xie
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China.,Key Laboratory of Molecular Epidemiology of Hunan Province, School of Medicine, Hunan Normal University, 410013, Changsha, China
| | - Yi-Ke Liu
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Zong-Pei Guo
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China
| | - Hua Guan
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China
| | - Xiao-Dan Liu
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China
| | - Da-Fei Xie
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China
| | - Yi-Guo Jiang
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China
| | - Teng Ma
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China. .,Department of Cellular and Molecular Biology, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis and Thoracic Tumor Research Institute, 101149, Beijing, China.
| | - Ping-Kun Zhou
- Department of Radiation Toxicology and Oncology, Beijing Institute of Radiation Medicine, 100850, Beijing, China. .,Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, 511436, Guangzhou, China.
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28
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The human Exonuclease-1 interactome and phosphorylation sites. Biochem Biophys Res Commun 2019; 514:567-573. [DOI: 10.1016/j.bbrc.2019.04.171] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 04/25/2019] [Indexed: 01/16/2023]
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29
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Godau J, Ferretti LP, Trenner A, Dubois E, von Aesch C, Marmignon A, Simon L, Kapusta A, Guérois R, Bétermier M, Sartori AA. Identification of a miniature Sae2/Ctp1/CtIP ortholog from Paramecium tetraurelia required for sexual reproduction and DNA double-strand break repair. DNA Repair (Amst) 2019; 77:96-108. [DOI: 10.1016/j.dnarep.2019.03.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2018] [Revised: 01/28/2019] [Accepted: 03/21/2019] [Indexed: 12/24/2022]
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30
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Eid W, Abdel-Rehim W. Genome-wide analysis of ETV1 targets: Insights into the role of ETV1 in tumor progression. J Cell Biochem 2019; 120:8983-8991. [PMID: 30629294 DOI: 10.1002/jcb.28169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 11/08/2018] [Indexed: 12/15/2022]
Abstract
ETS variant 1 (ETV1) is a key player in metastatic progression in several types of human cancers, yet the direct target genes of ETV1 and the mechanisms by which ETV1 exerts its deleterious function remain largely elusive. Here, we performed large-scale mapping and analysis of target loci of ETV1 in the prostate cancer cells LNCaP using the DNA adenine methyltransferase identification technique, we identified close to 800 direct targets for ETV1. Expression analysis using quantitative reverse transcription polymerase chain reaction confirmed a positive regulation by ETV1 in most of the genes examined. Furthermore, gene and pathway analysis unraveled new signaling pathways and biological networks that interact with ETV1. Our findings cast light on genes and networks regulated by ETV1, it also opens new fronts for studying the role of ETV1 and its target genes in tumorigenesis.
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Affiliation(s)
- Wassim Eid
- Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
| | - Wafaa Abdel-Rehim
- Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
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31
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Andres SN, Li ZM, Erie DA, Williams RS. Ctp1 protein-DNA filaments promote DNA bridging and DNA double-strand break repair. J Biol Chem 2019; 294:3312-3320. [PMID: 30626735 DOI: 10.1074/jbc.ra118.006759] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/26/2018] [Indexed: 12/13/2022] Open
Abstract
The Ctp1 protein in Schizosaccharomyces pombe is essential for DNA double-strand break (DSB) repair by homologous recombination. Fission yeast Ctp1 and its budding yeast (Sae2) and human (CtIP) homologs control Mre11-Rad50-Nbs1 nuclease complex activity and harbor DNA-binding and -bridging activities. However, the molecular basis for Ctp1-DNA transactions remains undefined. Here, we report atomic force microscopy (AFM) imaging of S. pombe Ctp1-DNA complexes revealing that Ctp1 polymerizes on dsDNA molecules and forms synaptic filaments that bridge two dsDNA strands. We observed that Ctp1 DNA filaments are typified by an average filament length of ∼180 bp of dsDNA and a Ctp1 tetramer footprint of ∼15 bp. Biochemical results characterizing Ctp1 variants with impaired DNA-binding or -bridging properties were consistent with Ctp1-mediated DNA bridging requiring the intact and correctly folded Ctp1 tetramer. Furthermore, mutations altering Ctp1 oligomerization and DNA bridging in vitro conferred cell sensitivity to DSB-producing agents. Together, these results support an important role for Ctp1-regulated DNA strand coordination required for DNA DSB repair in S. pombe.
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Affiliation(s)
- Sara N Andres
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709
| | - Zimeng M Li
- the Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27695, and
| | - Dorothy A Erie
- the Department of Chemistry, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, North Carolina 27599
| | - R Scott Williams
- From the Genome Integrity and Structural Biology Laboratory, NIEHS, National Institutes of Health, Department of Health and Human Services, Research Triangle Park, North Carolina 27709,
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32
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Chappidi N, De Gregorio G, Ferrari S. Replication stress-induced Exo1 phosphorylation is mediated by Rad53/Pph3 and Exo1 nuclear localization is controlled by 14-3-3 proteins. Cell Div 2019; 14:1. [PMID: 30622624 PMCID: PMC6318887 DOI: 10.1186/s13008-018-0044-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 12/24/2018] [Indexed: 12/22/2022] Open
Abstract
Background Mechanisms controlling DNA resection at sites of damage and affecting genome stability have been the subject of deep investigation, though their complexity is not yet fully understood. Specifically, the regulatory role of post-translational modifications in the localization, stability and function of DNA repair proteins is an important aspect of such complexity. Results Here, we took advantage of the superior resolution of phosphorylated proteins provided by Phos-Tag technology to study pathways controlling the reversible phosphorylation of yeast Exo1, an exonuclease involved in a number of DNA repair pathways. We report that Rad53, a checkpoint kinase downstream of Mec1, is responsible for Exo1 phosphorylation in response to DNA replication stress and we demonstrate a role for the type-2A protein phosphatase Pph3 in the dephosphorylation of both Rad53 and Exo1 during checkpoint recovery. Fluorescence microscopy studies showed that Rad53-dependent phosphorylation is not required for the recruitment or the release of Exo1 from the nucleus, whereas 14-3-3 proteins are necessary for Exo1 nuclear translocation. Conclusions By shedding light on the mechanism of Exo1 control, these data underscore the importance of post-translational modifications and protein interactions in the regulation of DNA end resection.
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Affiliation(s)
- Nagaraja Chappidi
- Institute of Molecular Cancer Research, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Giuseppe De Gregorio
- Institute of Molecular Cancer Research, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Stefano Ferrari
- Institute of Molecular Cancer Research, Winterthurerstrasse 190, 8057 Zurich, Switzerland
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33
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Jimeno S, Mejías-Navarro F, Prados-Carvajal R, Huertas P. Controlling the balance between chromosome break repair pathways. DNA Repair (Amst) 2019; 115:95-134. [DOI: 10.1016/bs.apcsb.2018.10.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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34
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Human Exonuclease 1 (EXO1) Regulatory Functions in DNA Replication with Putative Roles in Cancer. Int J Mol Sci 2018; 20:ijms20010074. [PMID: 30585186 PMCID: PMC6337416 DOI: 10.3390/ijms20010074] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 12/12/2018] [Accepted: 12/19/2018] [Indexed: 12/11/2022] Open
Abstract
Human exonuclease 1 (EXO1), a 5'→3' exonuclease, contributes to the regulation of the cell cycle checkpoints, replication fork maintenance, and post replicative DNA repair pathways. These processes are required for the resolution of stalled or blocked DNA replication that can lead to replication stress and potential collapse of the replication fork. Failure to restart the DNA replication process can result in double-strand breaks, cell-cycle arrest, cell death, or cellular transformation. In this review, we summarize the involvement of EXO1 in the replication, DNA repair pathways, cell cycle checkpoints, and the link between EXO1 and cancer.
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35
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CtIP-Mediated Fork Protection Synergizes with BRCA1 to Suppress Genomic Instability upon DNA Replication Stress. Mol Cell 2018; 72:568-582.e6. [DOI: 10.1016/j.molcel.2018.09.014] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 06/08/2018] [Accepted: 09/12/2018] [Indexed: 12/30/2022]
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36
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Rodríguez Gutiérrez D, Eid W, Biason-Lauber A. A Human Gonadal Cell Model From Induced Pluripotent Stem Cells. Front Genet 2018; 9:498. [PMID: 30405703 PMCID: PMC6207579 DOI: 10.3389/fgene.2018.00498] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Accepted: 10/05/2018] [Indexed: 11/20/2022] Open
Abstract
Sertoli cells are main players in the male gonads development and their study may shed light on 46,XY disorders of sex development (DSD). Mature primary Sertoli cells are incapable of proliferating in prolonged in vitro cultures and the available Sertoli cell models have several limitations since they derive from mouse or human cancer tissues. We differentiated human fibroblasts (HFs)-derived induced pluripotent stem cells into Sertoli-like cells (SLC) and, in order to characterize this new Sertoli cell model, we performed gene expression analyses by NextGeneration Sequencing techniques. This approach revealed that our putative SLC have reduced expression of pluripotency markers and expressed Sertoli cell markers such as SRY-Related HMG-Box 9 (SOX9), vimentin (VIM), and claudin-11 (CLDN-11). More in detail, the transcriptional profile analysis suggested that these cells are in an early stage of Sertoli cells maturation. Harnessing the power of induced pluripotent stem cells, we were able to generate SLC that show genetic and functional similarities to human Sertoli cells (HSerCs). SLC could become an excellent source of patient-specific Sertoli cells that could be of paramount benefit for both basic research and personalized medicine in sex development and reproductive medicine.
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Affiliation(s)
| | - Wassim Eid
- Section of Medicine, Endocrinology Division, University of Fribourg, Fribourg, Switzerland.,Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
| | - Anna Biason-Lauber
- Section of Medicine, Endocrinology Division, University of Fribourg, Fribourg, Switzerland
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Meiotic Double-Strand Break Proteins Influence Repair Pathway Utilization. Genetics 2018; 210:843-856. [PMID: 30242011 DOI: 10.1534/genetics.118.301402] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 09/13/2018] [Indexed: 12/13/2022] Open
Abstract
Double-strand breaks (DSBs) are among the most deleterious lesions DNA can endure. Yet, DSBs are programmed at the onset of meiosis, and are required to facilitate appropriate reduction of ploidy in daughter cells. Repair of these breaks is tightly controlled to favor homologous recombination (HR)-the only repair pathway that can form crossovers. However, little is known about how the activities of alternative repair pathways are regulated at these stages. We discovered an unexpected synthetic interaction between the DSB machinery and strand-exchange proteins. Depleting the Caenorhabditis elegans DSB-promoting factors HIM-5 and DSB-2 suppresses the formation of chromosome fusions that arise in the absence of RAD-51 or other strand-exchange mediators. Our investigations reveal that nonhomologous and theta-mediated end joining (c-NHEJ and TMEJ, respectively) and single strand annealing (SSA) function redundantly to repair DSBs when HR is compromised, and that HIM-5 influences the utilization of TMEJ and SSA.
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Sproll P, Eid W, Gomes CR, Mendonca BB, Gomes NL, Costa EMF, Biason-Lauber A. Assembling the jigsaw puzzle: CBX2 isoform 2 and its targets in disorders/differences of sex development. Mol Genet Genomic Med 2018; 6:785-795. [PMID: 29998616 PMCID: PMC6160712 DOI: 10.1002/mgg3.445] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 06/13/2018] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND One of the defining moments of human life occurs early during embryonic development, when individuals sexually differentiate into either male or female. Perturbation of this process can lead to disorders/differences of sex development (DSD). Chromobox protein homolog 2 (CBX2) has two distinct isoforms, CBX2.1 and CBX2.2: the role of CBX2.1 in DSD has been previously established, yet to date the function of the smaller isoform CBX2.2 remains unknown. METHODS The genomic DNA of two 46,XY DSD patients was analysed using whole exome sequencing. Furthermore, protein/DNA interaction studies were performed using DNA adenine methyltransferase identification (DamID) to identify putative binding partners of CBX2. Finally, in vitro functional studies were used to elucidate the effect of wild-type and variant CBX2.2 on selected downstream targets. RESULTS Here, we describe two patients with features of DSD i.e. atypical external genitalia, perineal hypospadias and no palpable gonads, each patient carrying a distinct CBX2.2 variant, p.Cys132Arg (c.394T>C) and p.Cys154fs (c.460delT). We show that both CBX2.2 variants fail to regulate the expression of genes essential for sexual development, leading to a severe 46,XY DSD defect, likely because of a defective expression of EMX2 in the developing gonad. CONCLUSION Our study indicates a distinct function of the shorter form of CBX2 and by identifying several of its unique targets, can advance our understanding of DSD pathogenesis and ultimately DSD diagnosis and management.
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Affiliation(s)
- Patrick Sproll
- Division of Endocrinology, University of Fribourg, Fribourg, Switzerland
| | - Wassim Eid
- Division of Endocrinology, University of Fribourg, Fribourg, Switzerland.,Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
| | - Camila R Gomes
- Medical School, University of Sao Paulo, Sao Paulo, Brazil
| | | | | | | | - Anna Biason-Lauber
- Division of Endocrinology, University of Fribourg, Fribourg, Switzerland
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Mijnes J, Veeck J, Gaisa NT, Burghardt E, de Ruijter TC, Gostek S, Dahl E, Pfister D, Schmid SC, Knüchel R, Rose M. Promoter methylation of DNA damage repair (DDR) genes in human tumor entities: RBBP8/ CtIP is almost exclusively methylated in bladder cancer. Clin Epigenetics 2018; 10:15. [PMID: 29445424 PMCID: PMC5802064 DOI: 10.1186/s13148-018-0447-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Accepted: 01/22/2018] [Indexed: 01/18/2023] Open
Abstract
Background Genome-wide studies identified pan-cancer genes and shared biological networks affected by epigenetic dysregulation among diverse tumor entities. Here, we systematically screened for hypermethylation of DNA damage repair (DDR) genes in a comprehensive candidate-approach and exemplarily identify and validate candidate DDR genes as targets of epigenetic inactivation unique to bladder cancer (BLCA), which may serve as non-invasive biomarkers. Methods Genome-wide DNA methylation datasets (2755 CpG probes of n = 7819 tumor and n = 659 normal samples) of the TCGA network covering 32 tumor entities were analyzed in silico for 177 DDR genes. Genes of interest were defined as differentially methylated between normal and cancerous tissues proximal to transcription start sites. The lead candidate gene was validated by methylation-specific PCR (MSP) and/or bisulfite-pyrosequencing in different human cell lines (n = 36), in primary BLCA tissues (n = 43), and in voided urine samples (n = 74) of BLCA patients. Urines from healthy donors and patients with urological benign and malignant diseases were included as controls (n = 78). mRNA expression was determined using qRT-PCR in vitro before (n = 5) and after decitabine treatment (n = 2). Protein expression was assessed by immunohistochemistry (n = 42). R 3.2.0. was used for statistical data acquisition and SPSS 21.0 for statistical analysis. Results Overall, 39 DDR genes were hypermethylated in human cancers. Most exclusively and frequently methylated (37%) in primary BLCA was RBBP8, encoding endonuclease CtIP. RBBP8 hypermethylation predicted longer overall survival (OS) and was found in 2/4 bladder cancer cell lines but not in any of 33 cancer cell lines from entities with another origin like prostate. RBBP8 methylation was inversely correlated with RBBP8 mRNA and nuclear protein expression while RBBP8 was re-expressed after in vitro demethylation. RBBP8 methylation was associated with histological grade in primary BLCA and urine samples. RBBP8 methylation was detectable in urine samples of bladder cancer patients achieving a sensitivity of 52%, at 91% specificity. Conclusions RBBP8 was identified as almost exclusively hypermethylated in BLCA. RBBP8/CtIP has a proven role in homologous recombination-mediated DNA double-strand break repair known to sensitize cancer cells for PARP1 inhibitors. Since RBBP8 methylation was detectable in urines, it may be a complementary marker of high specificity in urine for BLCA detection.
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Affiliation(s)
- Jolein Mijnes
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Jürgen Veeck
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany.,2Division of Medical Oncology, Maastricht University Medical Centre, Maastricht, The Netherlands.,3GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands.,4RWTH Centralized Biomaterial Bank (RWTH cBMB), Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - Nadine T Gaisa
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Eduard Burghardt
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Tim C de Ruijter
- 2Division of Medical Oncology, Maastricht University Medical Centre, Maastricht, The Netherlands.,3GROW-School for Oncology and Developmental Biology, Maastricht University Medical Centre, Maastricht, The Netherlands
| | - Sonja Gostek
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Edgar Dahl
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany.,4RWTH Centralized Biomaterial Bank (RWTH cBMB), Medical Faculty, RWTH Aachen University, Aachen, Germany
| | - David Pfister
- 5Department of Urology, RWTH Aachen University, Aachen, Germany.,6Department of Urology, Uro-Oncology, Robot Assisted and Reconstructive Urologic Surgery, University Hospital Cologne, Cologne, Germany
| | - Sebastian C Schmid
- 7Department of Urology, Klinikum rechts der Isar, Technical University Munich, Munich, Germany
| | - Ruth Knüchel
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany
| | - Michael Rose
- 1Institute of Pathology, RWTH Aachen University, Pauwelsstr. 30, 52074 Aachen, Germany.,4RWTH Centralized Biomaterial Bank (RWTH cBMB), Medical Faculty, RWTH Aachen University, Aachen, Germany
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Eid W, Biason-Lauber A. Why boys will be boys and girls will be girls: Human sex development and its defects. ACTA ACUST UNITED AC 2017; 108:365-379. [PMID: 28033664 DOI: 10.1002/bdrc.21143] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Among the most defining events of an individual's life, is the development of a human embryo into male or a female. The phenotypic sex of an individual depends on the type of gonad that develops in the embryo, a process which itself is determined by the genetic setting of the individual. The development of the gonads is different from any other organ, as they possess the potential to differentiate into two functionally distinct organs, testes, or ovaries. Sex development can be divided into two distinctive processes, "sex determination," which is the commitment of the undifferentiated gonad into either a testis or an ovary, a process that is genetically programmed in a critically timed manner and "sex differentiation," which takes place through hormones produced by the gonads, once the developmental sex determination decision has been made. Disruption of any of the genes involved in either the testicular or ovarian development pathway could lead to disorders of sex development. In this review, we provide an insight into the factors important for sex determination, their antagonistic actions and whenever possible, references on the "prismatic" clinical cases are given. Birth Defects Research (Part C) 108:365-379, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Wassim Eid
- Division of Endocrinology, Department of Medicine, University of Fribourg, Fribourg, Switzerland.,Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
| | - Anna Biason-Lauber
- Division of Endocrinology, Department of Medicine, University of Fribourg, Fribourg, Switzerland
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41
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Shibata A. Regulation of repair pathway choice at two-ended DNA double-strand breaks. Mutat Res 2017; 803-805:51-55. [PMID: 28781144 DOI: 10.1016/j.mrfmmm.2017.07.011] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/08/2017] [Accepted: 07/03/2017] [Indexed: 12/29/2022]
Abstract
A DNA double-strand break (DSB) is considered to be a critical DNA lesion because its misrepair can cause severe mutations, such as deletions or chromosomal translocations. For the precise repair of DSBs, the repair pathway that is optimal for the particular circumstance needs to be selected. Non-homologous end joining (NHEJ) functions in G1/S/G2 phase, while homologous recombination (HR) becomes active only in S/G2 phase after DNA replication. DSB end structure is another factor affecting the repair pathway. For example, one-ended DSBs in S phase are mainly repaired by HR due to the lack of a partner DSB end for NHEJ. In contrast, two-ended DSBs, which are mainly induced by ionizing radiation, are repaired by either NHEJ or HR in G2 cells. Under the current model in terms of DSB repair pathway usage in G2 phase, NHEJ repairs ∼70% of two-ended DSBs, whereas HR repairs only ∼30%. Recent studies propose that NHEJ factors can bind all the DSB ends and are then either used to progress that pathway of DSB repair, or the repair proceeds by HR. In addition, molecular regulation by BRCA1 and 53BP1 has also been proposed. At DSB sites, BRCA1 functions to alleviate the 53BP1 barrier to resection by promoting 53BP1 dephosphorylation, followed by RIF1 release and 53BP1 repositioning. This timely 53BP1 repositioning may be important for the establishment of a chromatin environment that promotes the recruitment of EXO1 for resection in HR. This review summarizes current knowledge on factors regulating DSB repair pathway choice in terms of spatiotemporal regulation by focusing on the repair events at two-ended DSBs in G2 cells.
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Affiliation(s)
- Atsushi Shibata
- Education and Research Support Center, Gunma University and Graduate School of Medicine, 3-39-22 Showa-machi, Maebashi, Gunma, 371-8511, Japan.
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42
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Tomimatsu N, Mukherjee B, Harris JL, Boffo FL, Hardebeck MC, Potts PR, Khanna KK, Burma S. DNA-damage-induced degradation of EXO1 exonuclease limits DNA end resection to ensure accurate DNA repair. J Biol Chem 2017; 292:10779-10790. [PMID: 28515316 PMCID: PMC5491765 DOI: 10.1074/jbc.m116.772475] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 05/11/2017] [Indexed: 12/22/2022] Open
Abstract
End resection of DNA double-strand breaks (DSBs) to generate 3'-single-stranded DNA facilitates DSB repair via error-free homologous recombination (HR) while stymieing repair by the error-prone non-homologous end joining (NHEJ) pathway. Activation of DNA end resection involves phosphorylation of the 5' to 3' exonuclease EXO1 by the phosphoinositide 3-kinase-like kinases ATM (ataxia telangiectasia-mutated) and ATR (ATM and Rad3-related) and by the cyclin-dependent kinases 1 and 2. After activation, EXO1 must also be restrained to prevent over-resection that is known to hamper optimal HR and trigger global genomic instability. However, mechanisms by which EXO1 is restrained are still unclear. Here, we report that EXO1 is rapidly degraded by the ubiquitin-proteasome system soon after DSB induction in human cells. ATR inhibition attenuated DNA-damage-induced EXO1 degradation, indicating that ATR-mediated phosphorylation of EXO1 targets it for degradation. In accord with these results, EXO1 became resistant to degradation when its SQ motifs required for ATR-mediated phosphorylation were mutated. We show that upon the induction of DNA damage, EXO1 is ubiquitinated by a member of the Skp1-Cullin1-F-box (SCF) family of ubiquitin ligases in a phosphorylation-dependent manner. Importantly, expression of degradation-resistant EXO1 resulted in hyper-resection, which attenuated both NHEJ and HR and severely compromised DSB repair resulting in chromosomal instability. These findings indicate that the coupling of EXO1 activation with its eventual degradation is a timing mechanism that limits the extent of DNA end resection for accurate DNA repair.
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Affiliation(s)
- Nozomi Tomimatsu
- From the Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Bipasha Mukherjee
- From the Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Janelle Louise Harris
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia
| | - Francesca Ludovica Boffo
- Department of Molecular Medicine and Medical Biotechnology, Università Federico II, Napoli 80131, Italy, and
| | - Molly Catherine Hardebeck
- From the Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Patrick Ryan Potts
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Kum Kum Khanna
- Signal Transduction Laboratory, QIMR Berghofer Medical Research Institute, Brisbane, Queensland 4006, Australia
| | - Sandeep Burma
- From the Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, Texas 75390,
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Gole B, Mian E, Rall M, Wiesmüller L. Base excision repair proteins couple activation-induced cytidine deaminase and endonuclease G during replication stress-induced MLL destabilization. Leukemia 2017. [PMID: 28626219 DOI: 10.1038/leu.2017.191] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The breakpoint cluster region of the MLL gene (MLLbcr) is frequently rearranged in therapy-related and infant acute leukaemia, but the destabilizing mechanism is poorly understood. We recently proposed that DNA replication stress results in MLLbcr cleavage via endonuclease G (EndoG) and represents the common denominator of genotoxic therapy-induced MLL destabilization. Here we performed a siRNA screen for new factors involved in replication stress-induced MLL rearrangements employing an enhanced green fluorescent protein-based reporter system. We identified 10 factors acting in line with EndoG in MLLbcr breakage or further downstream in the repair of the MLLbcr breaks, including activation-induced cytidine deaminase (AID), previously proposed to initiate MLLbcr rearrangements in an RNA transcription-dependent mechanism. Further analysis connected AID and EndoG in MLLbcr destabilization via base excision repair (BER) components. We show that replication stress-induced recruitment of EndoG to the MLLbcr and cleavage are AID/BER dependent. Notably, inhibition of the core BER factor Apurinic-apyrimidinic endonuclease 1 protects against MLLbcr cleavage in tumour and human cord blood-derived haematopoietic stem/progenitor cells, harbouring the cells of origin of leukaemia. We propose that off-target binding of AID to the MLLbcr initiates BER-mediated single-stranded DNA cleavage, which causes derailed EndoG activity ultimately resulting in leukaemogenic MLLbcr rearrangements.
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Affiliation(s)
- B Gole
- Gynaecological Oncology, Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - E Mian
- Gynaecological Oncology, Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - M Rall
- Gynaecological Oncology, Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
| | - L Wiesmüller
- Gynaecological Oncology, Department of Obstetrics and Gynaecology, Ulm University, Ulm, Germany
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Yin K, Chhabra Y, Tropée R, Lim YC, Fane M, Dray E, Sturm RA, Smith AG. NR4A2 Promotes DNA Double-strand Break Repair Upon Exposure to UVR. Mol Cancer Res 2017; 15:1184-1196. [PMID: 28607006 DOI: 10.1158/1541-7786.mcr-17-0002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 04/07/2017] [Accepted: 06/06/2017] [Indexed: 11/16/2022]
Abstract
Exposure of melanocytes to ultraviolet radiation (UVR) induces the formation of UV lesions that can produce deleterious effects in genomic DNA. Encounters of replication forks with unrepaired UV lesions can lead to several complex phenomena, such as the formation of DNA double-strand breaks (DSBs). The NR4A family of nuclear receptors are transcription factors that have been associated with mediating DNA repair functions downstream of the MC1R signaling pathway in melanocytes. In particular, emerging evidence shows that upon DNA damage, the NR4A2 receptor can translocate to sites of UV lesion by mechanisms requiring post-translational modifications within the N-terminal domain and at a serine residue in the DNA-binding domain at position 337. Following this, NR4A2 aids in DNA repair by facilitating chromatin relaxation, allowing accessibility for DNA repair machinery. Using A2058 and HT144 melanoma cells engineered to stably express wild-type or mutant forms of the NR4A2 proteins, we reveal that the expression of functional NR4A2 is associated with elevated cytoprotection against UVR. Conversely, knockdown of NR4A2 expression by siRNA results in a significant loss of cell viability after UV insult. By analyzing the kinetics of the ensuing 53BP1 and RAD51 foci following UV irradiation, we also reveal that the expression of mutant NR4A2 isoforms, lacking the ability to translocate, transactivate, or undergo phosphorylation, display compromised repair capacity.Implications: These data expand the understanding of the mechanism by which the NR4A2 nuclear receptor can facilitate DNA DSB repair. Mol Cancer Res; 15(9); 1184-96. ©2017 AACR.
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Affiliation(s)
- Kelvin Yin
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Yash Chhabra
- Queensland University of Technology, Translational Research Institute, Brisbane, Queensland, Australia.,Dermatology Research Centre, The University of Queensland-Diamantina Institute, Translational Research Institute, Brisbane, Queensland, Australia
| | - Romain Tropée
- Queensland University of Technology, Translational Research Institute, Brisbane, Queensland, Australia
| | - Yi Chieh Lim
- Translational Brain Cancer Research, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia
| | - Mitchell Fane
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Eloise Dray
- Queensland University of Technology, Translational Research Institute, Brisbane, Queensland, Australia.,Queensland University of Technology, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia.,Mater Research - The University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Richard A Sturm
- Dermatology Research Centre, The University of Queensland-Diamantina Institute, Translational Research Institute, Brisbane, Queensland, Australia
| | - Aaron G Smith
- Dermatology Research Centre, The University of Queensland-Diamantina Institute, Translational Research Institute, Brisbane, Queensland, Australia. .,Queensland University of Technology, Institute of Health and Biomedical Innovation, Kelvin Grove, Queensland, Australia
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45
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Eid W, Abdel-Rehim W. Neferine Enhances the Antitumor Effect of Mitomycin-C in Hela Cells Through the Activation of p38-MAPK Pathway. J Cell Biochem 2017; 118:3472-3479. [PMID: 28328092 DOI: 10.1002/jcb.26006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 03/21/2017] [Indexed: 01/07/2023]
Abstract
Current treatment options for patients with cervical cancer are far from desirable, with cervical cancer remaining to be one of the leading causes of cancer-related deaths; this highlights the need to formulate strategies that enhance the efficacy of available therapies. Mitomycin C (MMC) possesses antitumor effect in different cancers. However, the efficacy of MMC depends on other drugs in the combinational therapy and is often hampered by side-effects. Neferine, a natural alkaloid, exhibits antitumor effects in various cancers. In this study, we questioned the antitumor efficacy of a combinational treatment of neferine and MMC in cervical cancer cells. We found that neferine prominently enhanced the antitumor effects of MMC; this effect was dependent on the induction of apoptosis. Furthermore, we also provide a mechanistic insight and show that the enhanced apoptosis was a result of at least in part, a sustained activation of the p38 MAPK pathway in a ROS-dependent mechanism. Our results therefore demonstrate the potentiated antitumor effect of neferine and MMC on cervical cancer cells and may offer a potential treatment strategy for patients with cervical cancer. J. Cell. Biochem. 118: 3472-3479, 2017. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Wassim Eid
- Division of Endocrinology, Department of Medicine, University of Fribourg, Fribourg, 1700, Switzerland.,Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
| | - Wafaa Abdel-Rehim
- Department of Biochemistry, Medical Research Institute, University of Alexandria, Alexandria, Egypt
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Hilmi K, Jangal M, Marques M, Zhao T, Saad A, Zhang C, Luo VM, Syme A, Rejon C, Yu Z, Krum A, Fabian MR, Richard S, Alaoui-Jamali M, Orthwein A, McCaffrey L, Witcher M. CTCF facilitates DNA double-strand break repair by enhancing homologous recombination repair. SCIENCE ADVANCES 2017; 3:e1601898. [PMID: 28560323 PMCID: PMC5443639 DOI: 10.1126/sciadv.1601898] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 03/29/2017] [Indexed: 05/06/2023]
Abstract
The repair of DNA double-strand breaks (DSBs) is mediated via two major pathways, nonhomologous end joining (NHEJ) and homologous recombination (HR) repair. DSB repair is vital for cell survival, genome stability, and tumor suppression. In contrast to NHEJ, HR relies on extensive homology and templated DNA synthesis to restore the sequence surrounding the break site. We report a new role for the multifunctional protein CCCTC-binding factor (CTCF) in facilitating HR-mediated DSB repair. CTCF is recruited to DSB through its zinc finger domain independently of poly(ADP-ribose) polymers, known as PARylation, catalyzed by poly(ADP-ribose) polymerase 1 (PARP-1). CTCF ensures proper DSB repair kinetics in response to γ-irradiation, and the loss of CTCF compromises HR-mediated repair. Consistent with its role in HR, loss of CTCF results in hypersensitivity to DNA damage, inducing agents and inhibitors of PARP. Mechanistically, CTCF acts downstream of BRCA1 in the HR pathway and associates with BRCA2 in a PARylation-dependent manner, enhancing BRCA2 recruitment to DSB. In contrast, CTCF does not influence the recruitment of the NHEJ protein 53BP1 or LIGIV to DSB. Together, our findings establish for the first time that CTCF is an important regulator of the HR pathway.
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Affiliation(s)
- Khalid Hilmi
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Maïka Jangal
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Maud Marques
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Tiejun Zhao
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Amine Saad
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Chenxi Zhang
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Vincent M. Luo
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
- Department of Microbiology and Immunology, McGill University, 3775 University Street, Montréal, Quebec H3A 2B4, Canada
| | - Alasdair Syme
- Department of Radiation Oncology, Medical Physics Unit, Jewish General Hospital, McGill University, Montréal, Quebec H3T 1E2, Canada
| | - Carlis Rejon
- Department of Oncology, Rosalind and Morris Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue West, Montréal, Quebec H3A 1A3, Canada
| | - Zhenbao Yu
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Asiev Krum
- Department of Radiation Oncology, Medical Physics Unit, Jewish General Hospital, McGill University, Montréal, Quebec H3T 1E2, Canada
| | - Marc R. Fabian
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Stéphane Richard
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Moulay Alaoui-Jamali
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
| | - Alexander Orthwein
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
- Department of Microbiology and Immunology, McGill University, 3775 University Street, Montréal, Quebec H3A 2B4, Canada
| | - Luke McCaffrey
- Department of Oncology, Rosalind and Morris Goodman Cancer Research Centre, McGill University, 1160 Pine Avenue West, Montréal, Quebec H3A 1A3, Canada
| | - Michael Witcher
- Departments of Oncology and Experimental Medicine, Lady Davis Institute and Segal Cancer Centre, Jewish General Hospital, McGill University, 3755 Chemin Côte-Ste-Catherine, Montréal, Quebec H3T 1E2, Canada
- Corresponding author.
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47
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Differences in the recruitment of DNA repair proteins at subtelomeric and interstitial I-SceI endonuclease-induced DNA double-strand breaks. DNA Repair (Amst) 2016; 49:1-8. [PMID: 27842255 DOI: 10.1016/j.dnarep.2016.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 09/21/2016] [Accepted: 10/26/2016] [Indexed: 12/28/2022]
Abstract
Telomeres are nucleoprotein structures that are required to protect chromosome ends. Dysfunctional telomeres are recognized as DNA double-strand breaks (DSBs), and elicit the activation of a DNA damage response (DDR). We have previously reported that DSBs near telomeres are poorly repaired, resulting in a high frequency of large deletions and gross chromosome rearrangements (GCRs). Our previous genetic studies have demonstrated that this sensitivity of telomeric regions to DSBs is a result of excessive processing. In the current study, we have further investigated the sensitivity of telomeric regions to DSBs through the analysis of repair proteins associated with DSBs at interstitial and telomeric sites. Following the inducible expression of I-SceI endonuclease, chromatin immunoprecipitation (ChIP) and real-time quantitative PCR were used to compare the recruitment of repair proteins at I-SceI-induced DSBs at interstitial and subtelomeric sites. We observed that proteins that are specifically associated with processing of DSBs during homologous recombination repair, RAD51, BRCA1, and CtIP, are present at a much greater abundance at subtelomeric DSBs. In contrast, Ku70, which is specifically involved in classical nonhomologous end joining, showed no difference at interstitial and subtelomeric DSBs. Importantly, ATM was lower in abundance at subtelomeric DSBs, while ATR was in greater abundance at subtelomeric DSBs, consistent with the accumulation of processed DSBs near telomeres, since processing is accompanied by a transition from ATM to ATR binding. Combined, our results suggest that excessive processing is responsible for the increased frequency of large deletions and GCRs at DSBs near telomeres.
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48
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Eid W, Abdel-Rehim W. Vitamin C promotes pluripotency of human induced pluripotent stem cells via the histone demethylase JARID1A. Biol Chem 2016; 397:1205-1213. [DOI: 10.1515/hsz-2016-0181] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 06/22/2016] [Indexed: 01/06/2023]
Abstract
Abstract
Somatic cells can be reprogramed into induced pluripotent stem (iPS) cells by defined factors, which provide a powerful basis for personalized stem-cell based therapies. However, cellular reprograming is an inefficient and metabolically demanding process commonly associated with obstacles that hamper further use of this technology. Spontaneous differentiation of iPS cells cultures represents a significant hurdle that hinder obtaining high quality iPS cells for further downstream experimentation. In this study, we found that a natural compound, vitamin C, augmented pluripotency in iPS cells and reduced unwanted spontaneous differentiation during iPS cells maintenance. Gene expression analysis showed that vitamin C increased the expression of the histone demethylase JARID1A. Furthermore, through gain- and loss-of-function approaches, we show that JARID1A is a key effector in promoting pluripotency and reducing differentiation downstream of vitamin C. Our results therefore highlight a straightforward method for improving the pluripotency and quality of iPS cells; it also shows a possible role for H3K4me2/3 in cell fate determination and establishes a link between vitamin C and epigenetic regulation.
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49
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Cullin3-KLHL15 ubiquitin ligase mediates CtIP protein turnover to fine-tune DNA-end resection. Nat Commun 2016; 7:12628. [PMID: 27561354 PMCID: PMC5007465 DOI: 10.1038/ncomms12628] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 07/19/2016] [Indexed: 12/16/2022] Open
Abstract
Human CtIP is a decisive factor in DNA double-strand break repair pathway choice by enabling DNA-end resection, the first step that differentiates homologous recombination (HR) from non-homologous end-joining (NHEJ). To coordinate appropriate and timely execution of DNA-end resection, CtIP function is tightly controlled by multiple protein-protein interactions and post-translational modifications. Here, we identify the Cullin3 E3 ligase substrate adaptor Kelch-like protein 15 (KLHL15) as a new interaction partner of CtIP and show that KLHL15 promotes CtIP protein turnover via the ubiquitin-proteasome pathway. A tripeptide motif (FRY) conserved across vertebrate CtIP proteins is essential for KLHL15-binding; its mutation blocks KLHL15-dependent CtIP ubiquitination and degradation. Consequently, DNA-end resection is strongly attenuated in cells overexpressing KLHL15 but amplified in cells either expressing a CtIP-FRY mutant or lacking KLHL15, thus impacting the balance between HR and NHEJ. Collectively, our findings underline the key importance and high complexity of CtIP modulation for genome integrity.
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50
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Keijzers G, Liu D, Rasmussen LJ. Exonuclease 1 and its versatile roles in DNA repair. Crit Rev Biochem Mol Biol 2016; 51:440-451. [PMID: 27494243 DOI: 10.1080/10409238.2016.1215407] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Exonuclease 1 (EXO1) is a multifunctional 5' → 3' exonuclease and a DNA structure-specific DNA endonuclease. EXO1 plays roles in DNA replication, DNA mismatch repair (MMR) and DNA double-stranded break repair (DSBR) in lower and higher eukaryotes and contributes to meiosis, immunoglobulin maturation, and micro-mediated end-joining in higher eukaryotes. In human cells, EXO1 is also thought to play a role in telomere maintenance. Mutations in the human EXO1 gene correlate with increased susceptibility to some cancers. This review summarizes recent studies on the enzymatic functions and biological roles of EXO1, its possible protective role against cancer and aging, and regulation of EXO1 by posttranslational modification.
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Affiliation(s)
- Guido Keijzers
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
| | - Dekang Liu
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
| | - Lene Juel Rasmussen
- a Department of Cellular and Molecular Medicine , Center for Healthy Aging, University of Copenhagen , Copenhagen , Denmark
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