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Wu J, Song L, Lu M, Gao Q, Xu S, Zhou P, Ma T. The multifaceted functions of DNA-PKcs: implications for the therapy of human diseases. MedComm (Beijing) 2024; 5:e613. [PMID: 38898995 PMCID: PMC11185949 DOI: 10.1002/mco2.613] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 05/07/2024] [Accepted: 05/09/2024] [Indexed: 06/21/2024] Open
Abstract
The DNA-dependent protein kinase (DNA-PK), catalytic subunit, also known as DNA-PKcs, is complexed with the heterodimer Ku70/Ku80 to form DNA-PK holoenzyme, which is well recognized as initiator in the nonhomologous end joining (NHEJ) repair after double strand break (DSB). During NHEJ, DNA-PKcs is essential for both DNA end processing and end joining. Besides its classical function in DSB repair, DNA-PKcs also shows multifaceted functions in various biological activities such as class switch recombination (CSR) and variable (V) diversity (D) joining (J) recombination in B/T lymphocytes development, innate immunity through cGAS-STING pathway, transcription, alternative splicing, and so on, which are dependent on its function in NHEJ or not. Moreover, DNA-PKcs deficiency has been proven to be related with human diseases such as neurological pathogenesis, cancer, immunological disorder, and so on through different mechanisms. Therefore, it is imperative to summarize the latest findings about DNA-PKcs and diseases for better targeting DNA-PKcs, which have shown efficacy in cancer treatment in preclinical models. Here, we discuss the multifaceted roles of DNA-PKcs in human diseases, meanwhile, we discuss the progresses of DNA-PKcs inhibitors and their potential in clinical trials. The most updated review about DNA-PKcs will hopefully provide insights and ideas to understand DNA-PKcs associated diseases.
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Affiliation(s)
- Jinghong Wu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Liwei Song
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Mingjun Lu
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Qing Gao
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Shaofa Xu
- Department of Thoracic SurgeryBeijing Chest HospitalCapital Medical University, Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
| | - Ping‐Kun Zhou
- Beijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Teng Ma
- Cancer Research CenterBeijing Chest HospitalCapital Medical University/Beijing Tuberculosis and Thoracic Tumor Research InstituteBeijingChina
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2
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Tan J, Sun X, Zhao H, Guan H, Gao S, Zhou P. Double-strand DNA break repair: molecular mechanisms and therapeutic targets. MedComm (Beijing) 2023; 4:e388. [PMID: 37808268 PMCID: PMC10556206 DOI: 10.1002/mco2.388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 08/29/2023] [Accepted: 09/08/2023] [Indexed: 10/10/2023] Open
Abstract
Double-strand break (DSB), a significant DNA damage brought on by ionizing radiation, acts as an initiating signal in tumor radiotherapy, causing cancer cells death. The two primary pathways for DNA DSB repair in mammalian cells are nonhomologous end joining (NHEJ) and homologous recombination (HR), which cooperate and compete with one another to achieve effective repair. The DSB repair mechanism depends on numerous regulatory variables. DSB recognition and the recruitment of DNA repair components, for instance, depend on the MRE11-RAD50-NBS1 (MRN) complex and the Ku70/80 heterodimer/DNA-PKcs (DNA-PK) complex, whose control is crucial in determining the DSB repair pathway choice and efficiency of HR and NHEJ. In-depth elucidation on the DSB repair pathway's molecular mechanisms has greatly facilitated for creation of repair proteins or pathways-specific inhibitors to advance precise cancer therapy and boost the effectiveness of cancer radiotherapy. The architectures, roles, molecular processes, and inhibitors of significant target proteins in the DSB repair pathways are reviewed in this article. The strategy and application in cancer therapy are also discussed based on the advancement of inhibitors targeted DSB damage response and repair proteins.
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Affiliation(s)
- Jinpeng Tan
- Hengyang Medical CollegeUniversity of South ChinaHengyangHunan ProvinceChina
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Xingyao Sun
- Hengyang Medical CollegeUniversity of South ChinaHengyangHunan ProvinceChina
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Hongling Zhao
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Hua Guan
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Shanshan Gao
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
| | - Ping‐Kun Zhou
- Hengyang Medical CollegeUniversity of South ChinaHengyangHunan ProvinceChina
- Department of Radiation BiologyBeijing Key Laboratory for RadiobiologyBeijing Institute of Radiation MedicineBeijingChina
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3
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Lu H, Zhang Q, Laverty DJ, Puncheon AC, Augustine M, Williams G, Nagel Z, Chen BC, Davis A. ATM phosphorylates the FATC domain of DNA-PKcs at threonine 4102 to promote non-homologous end joining. Nucleic Acids Res 2023; 51:6770-6783. [PMID: 37309889 PMCID: PMC10359628 DOI: 10.1093/nar/gkad505] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/14/2023] Open
Abstract
Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double-stranded breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Ablating phosphorylation at T4102 attenuates DNA-PKcs kinase activity and this destabilizes the interaction between DNA-PKcs and the Ku-DNA complex, resulting in decreased assembly and stabilization of the NHEJ machinery at DSBs. Phosphorylation at T4102 promotes NHEJ, radioresistance, and increases genomic stability following DSB induction. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PKcs.
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Affiliation(s)
- Huiming Lu
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Qin Zhang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Daniel J Laverty
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA02115, USA
| | - Andrew C Puncheon
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Mathew M Augustine
- Division of Surgical Oncology, Department of Surgery, UT Southwestern Medical Center, Dallas, TX75390, USA
- Department of Surgery, North Texas VA Medical Center, Dallas, TX75216, USA
| | - Gareth J Williams
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Zachary D Nagel
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA02115, USA
| | - Benjamin P C Chen
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Anthony J Davis
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
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4
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Lu H, Zhang Q, Laverty DJ, Puncheon AC, Williams GJ, Nagel ZD, Chen BP, Davis AJ. ATM phosphorylates the FATC domain of DNA-PK cs at threonine 4102 to promote non-homologous end joining. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526879. [PMID: 36778257 PMCID: PMC9915669 DOI: 10.1101/2023.02.02.526879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double strand breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PK cs ), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Phosphorylation at T4102 stabilizes the interaction between DNA-PK cs and the Ku-DNA complex and promotes assembly and stabilization of the NHEJ machinery at DSBs. Ablating phosphorylation at this site results in decreased NHEJ, radiosensitivity, and increased radiation-induced genomic instability. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PK cs .
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5
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Molecular targets that sensitize cancer to radiation killing: From the bench to the bedside. Biomed Pharmacother 2023; 158:114126. [PMID: 36521246 DOI: 10.1016/j.biopha.2022.114126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/05/2022] [Accepted: 12/09/2022] [Indexed: 12/15/2022] Open
Abstract
Radiotherapy is a standard cytotoxic therapy against solid cancers. It uses ionizing radiation to kill tumor cells through damage to DNA, either directly or indirectly. Radioresistance is often associated with dysregulated DNA damage repair processes. Most radiosensitizers enhance radiation-mediated DNA damage and reduce the rate of DNA repair ultimately leading to accumulation of DNA damages, cell-cycle arrest, and cell death. Recently, agents targeting key signals in DNA damage response such as DNA repair pathways and cell-cycle have been developed. This new class of molecularly targeted radiosensitizing agents is being evaluated in preclinical and clinical studies to monitor their activity in potentiating radiation cytotoxicity of tumors and reducing normal tissue toxicity. The molecular pathways of DNA damage response are reviewed with a focus on the repair mechanisms, therapeutic targets under current clinical evaluation including ATM, ATR, CDK1, CDK4/6, CHK1, DNA-PKcs, PARP-1, Wee1, & MPS1/TTK and potential new targets (BUB1, and DNA LIG4) for radiation sensitization.
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Hu C, Bugbee T, Palinski R, Akinyemi IA, McIntosh MT, MacCarthy T, Bhaduri-McIntosh S, Wallace N. Beta human papillomavirus 8E6 promotes alternative end joining. eLife 2023; 12:e81923. [PMID: 36692284 PMCID: PMC9897725 DOI: 10.7554/elife.81923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2022] [Accepted: 01/23/2023] [Indexed: 01/25/2023] Open
Abstract
Double strand breaks (DSBs) are one of the most lethal DNA lesions in cells. The E6 protein of beta-human papillomavirus (HPV8 E6) impairs two critical DSB repair pathways: homologous recombination (HR) and non-homologous end joining (NHEJ). However, HPV8 E6 only delays DSB repair. How DSBs are repaired in cells with HPV8 E6 remains to be studied. We hypothesize that HPV8 E6 promotes a less commonly used DSB repair pathway, alternative end joining (Alt-EJ). Using CAS9-based Alt-EJ reporters, we show that HPV8 E6 promotes Alt-EJ. Further, using small molecule inhibitors, CRISPR/CAS9 gene knockout, and HPV8 E6 mutant, we find that HPV8 E6 promotes Alt-EJ by binding p300, an acetyltransferase that facilitates DSB repair by HR and NHEJ. At least some of this repair occurs through a subset of Alt-EJ known as polymerase theta dependent end joining. Finally, whole genome sequencing analysis showed HPV8 E6 caused an increased frequency of deletions bearing the microhomology signatures of Alt-EJ. This study fills the knowledge gap of how DSB is repaired in cells with HPV8 E6 and the mutagenic consequences of HPV8 E6 mediated p300 destabilization. Broadly, this study supports the hypothesis that beta-HPV promotes cancer formation by increasing genomic instability.
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Affiliation(s)
- Changkun Hu
- Basic Sciences Division, Fred Hutchinson Cancer Research CenterSeattleUnited States
- Division of Biology, Kansas State UniversityManhattanUnited States
| | - Taylor Bugbee
- Division of Biology, Kansas State UniversityManhattanUnited States
| | - Rachel Palinski
- Veterinary Diagnostic Laboratory, Kansas State UniversityManhattanUnited States
| | - Ibukun A Akinyemi
- Child Health Research Institute, Department of Pediatrics, University of FloridaGainesvilleUnited States
- Department of Molecular Genetics and Microbiology, University of FloridaGainesvilleUnited States
| | - Michael T McIntosh
- Child Health Research Institute, Department of Pediatrics, University of FloridaGainesvilleUnited States
| | - Thomas MacCarthy
- Laufer Center for Physical and Quantitative Biology, Stony Brook UniversityStony BrookUnited States
| | - Sumita Bhaduri-McIntosh
- Child Health Research Institute, Department of Pediatrics, University of FloridaGainesvilleUnited States
- Department of Molecular Genetics and Microbiology, University of FloridaGainesvilleUnited States
| | - Nicholas Wallace
- Division of Biology, Kansas State UniversityManhattanUnited States
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7
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Lu H, Guan J, Wang SY, Li GM, Bohr VA, Davis AJ. DNA-PKcs-dependent phosphorylation of RECQL4 promotes NHEJ by stabilizing the NHEJ machinery at DNA double-strand breaks. Nucleic Acids Res 2022; 50:5635-5651. [PMID: 35580045 PMCID: PMC9178012 DOI: 10.1093/nar/gkac375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 04/25/2022] [Accepted: 05/03/2022] [Indexed: 12/21/2022] Open
Abstract
Non-homologous end joining (NHEJ) is the major pathway that mediates the repair of DNA double-strand breaks (DSBs) generated by ionizing radiation (IR). Previously, the DNA helicase RECQL4 was implicated in promoting NHEJ, but its role in the pathway remains unresolved. In this study, we report that RECQL4 stabilizes the NHEJ machinery at DSBs to promote repair. Specifically, we find that RECQL4 interacts with the NHEJ core factor DNA-PKcs and the interaction is increased following IR. RECQL4 promotes DNA end bridging mediated by DNA-PKcs and Ku70/80 in vitro and the accumulation/retention of NHEJ factors at DSBs in vivo. Moreover, interaction between DNA-PKcs and the other core NHEJ proteins following IR treatment is attenuated in the absence of RECQL4. These data indicate that RECQL4 promotes the stabilization of the NHEJ factors at DSBs to support formation of the NHEJ long-range synaptic complex. In addition, we observed that the kinase activity of DNA-PKcs is required for accumulation of RECQL4 to DSBs and that DNA-PKcs phosphorylates RECQL4 at six serine/threonine residues. Blocking phosphorylation at these sites reduced the recruitment of RECQL4 to DSBs, attenuated the interaction between RECQL4 and NHEJ factors, destabilized interactions between the NHEJ machinery, and resulted in decreased NHEJ. Collectively, these data illustrate reciprocal regulation between RECQL4 and DNA-PKcs in NHEJ.
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Affiliation(s)
- Huiming Lu
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Junhong Guan
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Shih-Ya Wang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Guo-Min Li
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Vilhelm A Bohr
- DNA Repair Section, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, USA
| | - Anthony J Davis
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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8
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Bergstrand S, O'Brien EM, Coucoravas C, Hrossova D, Peirasmaki D, Schmidli S, Dhanjal S, Pederiva C, Siggens L, Mortusewicz O, O'Rourke JJ, Farnebo M. Small Cajal body-associated RNA 2 (scaRNA2) regulates DNA repair pathway choice by inhibiting DNA-PK. Nat Commun 2022; 13:1015. [PMID: 35197472 PMCID: PMC8866460 DOI: 10.1038/s41467-022-28646-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 01/25/2022] [Indexed: 12/20/2022] Open
Abstract
Evidence that long non-coding RNAs (lncRNAs) participate in DNA repair is accumulating, however, whether they can control DNA repair pathway choice is unknown. Here we show that the small Cajal body-specific RNA 2 (scaRNA2) can promote HR by inhibiting DNA-dependent protein kinase (DNA-PK) and, thereby, NHEJ. By binding to the catalytic subunit of DNA-PK (DNA-PKcs), scaRNA2 weakens its interaction with the Ku70/80 subunits, as well as with the LINP1 lncRNA, thereby preventing catalytic activation of the enzyme. Inhibition of DNA-PK by scaRNA2 stimulates DNA end resection by the MRN/CtIP complex, activation of ATM at DNA lesions and subsequent repair by HR. ScaRNA2 is regulated in turn by WRAP53β, which binds this RNA, sequestering it away from DNA-PKcs and allowing NHEJ to proceed. These findings reveal that RNA-dependent control of DNA-PK catalytic activity is involved in regulating whether the cell utilizes NHEJ or HR. Proper repair of DNA double-strand breaks is essential for genomic stability. Here, the authors report that a long non-coding RNA, scaRNA2, inhibits DNA-PK and thereby regulates the choice between error-prone NHEJ and error-free HR DNA repair.
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Affiliation(s)
- Sofie Bergstrand
- Department of Biosciences and Nutrition, Neo, Karolinska Institutet, Stockholm, Sweden
| | - Eleanor M O'Brien
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Christos Coucoravas
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Dominika Hrossova
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Dimitra Peirasmaki
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Sandro Schmidli
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Soniya Dhanjal
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Chiara Pederiva
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Lee Siggens
- Department of Biosciences and Nutrition, Neo, Karolinska Institutet, Stockholm, Sweden
| | - Oliver Mortusewicz
- Department of Oncology and Pathology, SciLife, Karolinska Institutet, Stockholm, Sweden
| | - Julienne J O'Rourke
- Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden
| | - Marianne Farnebo
- Department of Biosciences and Nutrition, Neo, Karolinska Institutet, Stockholm, Sweden. .,Department of Cell and Molecular biology, Biomedicum, Karolinska Institutet, Stockholm, Sweden.
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9
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Ejaz S, Abbas Z, Nouroz F. Exceptional behavior of breast cancer-associated type 1 gene in breast invasive carcinoma. J Cancer Res Ther 2022; 18:1743-1753. [DOI: 10.4103/jcrt.jcrt_1310_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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10
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Ackerson SM, Romney C, Schuck PL, Stewart JA. To Join or Not to Join: Decision Points Along the Pathway to Double-Strand Break Repair vs. Chromosome End Protection. Front Cell Dev Biol 2021; 9:708763. [PMID: 34322492 PMCID: PMC8311741 DOI: 10.3389/fcell.2021.708763] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 06/17/2021] [Indexed: 01/01/2023] Open
Abstract
The regulation of DNA double-strand breaks (DSBs) and telomeres are diametrically opposed in the cell. DSBs are considered one of the most deleterious forms of DNA damage and must be quickly recognized and repaired. Telomeres, on the other hand, are specialized, stable DNA ends that must be protected from recognition as DSBs to inhibit unwanted chromosome fusions. Decisions to join DNA ends, or not, are therefore critical to genome stability. Yet, the processing of telomeres and DSBs share many commonalities. Accordingly, key decision points are used to shift DNA ends toward DSB repair vs. end protection. Additionally, DSBs can be repaired by two major pathways, namely homologous recombination (HR) and non-homologous end joining (NHEJ). The choice of which repair pathway is employed is also dictated by a series of decision points that shift the break toward HR or NHEJ. In this review, we will focus on these decision points and the mechanisms that dictate end protection vs. DSB repair and DSB repair choice.
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Affiliation(s)
- Stephanie M Ackerson
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Carlan Romney
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - P Logan Schuck
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
| | - Jason A Stewart
- Department of Biological Sciences, University of South Carolina, Columbia, SC, United States
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The CD44high Subpopulation of Multifraction Irradiation-Surviving NSCLC Cells Exhibits Partial EMT-Program Activation and DNA Damage Response Depending on Their p53 Status. Int J Mol Sci 2021; 22:ijms22052369. [PMID: 33673439 PMCID: PMC7956695 DOI: 10.3390/ijms22052369] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 02/15/2021] [Accepted: 02/24/2021] [Indexed: 02/07/2023] Open
Abstract
Ionizing radiation (IR) is used for patients diagnosed with unresectable non-small cell lung cancer (NSCLC). However, radiotherapy remains largely palliative due to the survival of specific cell subpopulations. In the present study, the sublines of NSCLC cells, A549IR (p53wt) and H1299IR (p53null) survived multifraction X-ray radiation exposure (MFR) at a total dose of 60 Gy were investigated three weeks after the MFR course. We compared radiosensitivity (colony formation), expression of epithelial-mesenchymal transition (EMT) markers, migration activity, autophagy, and HR-dependent DNA double-strand break (DSB) repair in the bulk and entire CD44high/CD166high CSC-like populations of both parental and MFR survived NSCLC cells. We demonstrated that the p53 status affected: the pattern of expression of N-cadherin, E-cadherin, Vimentin, witnessing the appearance of EMT-like phenotype of MFR-surviving sublines; 1D confined migratory behavior (wound healing); the capability of an irradiated cell to continue to divide and form a colony of NSCLC cells before and after MFR; influencing the CD44/CD166 expression level in MFR-surviving NSCLC cells after additional single irradiation. Our data further emphasize the impact of p53 status on the decay of γH2AX foci and the associated efficacy of the DSB repair in NSCLC cells survived after MFR. We revealed that Rad51 protein might play a principal role in MFR-surviving of p53 null NSCLC cells promoting DNA DSB repair by homologous recombination (HR) pathway. The proportion of Rad51 + cells elevated in CD44high/CD166high population in MFR-surviving p53wt and p53null sublines and their parental cells. The p53wt ensures DNA-PK-mediated DSB repair for both parental and MFR-surviving cells irrespectively of a subsequent additional single irradiation. Whereas in the absence of p53, a dose-dependent increase of DNA-PK-mediated non-homologous end joining (NHEJ) occurred as an early post-irradiation response is more intensive in the CSC-like population MFR-surviving H1299IR, compared to their parental H1299 cells. Our study strictly observed a significantly higher content of LC3 + cells in the CD44high/CD166high populations of p53wt MFR-surviving cells, which enriched the CSC-like cells in contrast to their p53null counterparts. The additional 2 Gy and 5 Gy X-ray exposure leads to the dose-dependent increase in the proportion of LC3 + cells in CD44high/CD166high population of both parental p53wt and p53null, but not MFR-surviving NSCLC sublines. Our data indicated that autophagy is not necessarily associated with CSC-like cells’ radiosensitivity, emphasizing that careful assessment of other milestone processes (such as senescence and autophagy-p53-Zeb1 axis) of primary radiation responses may provide new potential targets modulated for therapeutic benefit through radiosensitizing cancer cells while rescuing normal tissue. Our findings also shed light on the intricate crosstalk between autophagy and the p53-related EMT, by which MFR-surviving cells might obtain an invasive phenotype and metastatic potential.
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12
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CRL4A DTL degrades DNA-PKcs to modulate NHEJ repair and induce genomic instability and subsequent malignant transformation. Oncogene 2021; 40:2096-2111. [PMID: 33627782 PMCID: PMC7979543 DOI: 10.1038/s41388-021-01690-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 01/24/2021] [Accepted: 01/29/2021] [Indexed: 01/30/2023]
Abstract
Genomic instability induced by DNA damage and improper DNA damage repair is one of the main causes of malignant transformation and tumorigenesis. DNA double strand breaks (DSBs) are the most detrimental form of DNA damage, and nonhomologous end-joining (NHEJ) mechanisms play dominant and priority roles in initiating DSB repair. A well-studied oncogene, the ubiquitin ligase Cullin 4A (CUL4A), is reported to be recruited to DSB sites in genomic DNA, but whether it regulates NHEJ mechanisms of DSB repair is unclear. Here, we discovered that the CUL4A-DTL ligase complex targeted the DNA-PKcs protein in the NHEJ repair pathway for nuclear degradation. Overexpression of either CUL4A or DTL reduced NHEJ repair efficiency and subsequently increased the accumulation of DSBs. Moreover, we demonstrated that overexpression of either CUL4A or DTL in normal cells led to genomic instability and malignant proliferation. Consistent with the in vitro findings, in human precancerous lesions, CUL4A expression gradually increased with increasing malignant tendency and was negatively correlated with DNA-PKcs and positively correlated with γ-H2AX expression. Collectively, this study provided strong evidence that the CUL4A-DTL axis increases genomic instability and enhances the subsequent malignant transformation of normal cells by inhibiting NHEJ repair. These results also suggested that CUL4A may be a prognostic marker of precancerous lesions and a potential therapeutic target in cancer.
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13
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Yue X, Bai C, Xie D, Ma T, Zhou PK. DNA-PKcs: A Multi-Faceted Player in DNA Damage Response. Front Genet 2020; 11:607428. [PMID: 33424929 PMCID: PMC7786053 DOI: 10.3389/fgene.2020.607428] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 12/01/2020] [Indexed: 12/17/2022] Open
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a member of the phosphatidylinositol 3-kinase related kinase family, which can phosphorylate more than 700 substrates. As the core enzyme, DNA-PKcs forms the active DNA-PK holoenzyme with the Ku80/Ku70 heterodimer to play crucial roles in cellular DNA damage response (DDR). Once DNA double strand breaks (DSBs) occur in the cells, DNA-PKcs is promptly recruited into damage sites and activated. DNA-PKcs is auto-phosphorylated and phosphorylated by Ataxia-Telangiectasia Mutated at multiple sites, and phosphorylates other targets, participating in a series of DDR and repair processes, which determine the cells' fates: DSBs NHEJ repair and pathway choice, replication stress response, cell cycle checkpoints, telomeres length maintenance, senescence, autophagy, etc. Due to the special and multi-faceted roles of DNA-PKcs in the cellular responses to DNA damage, it is important to precisely regulate the formation and dynamic of its functional complex and activities for guarding genomic stability. On the other hand, targeting DNA-PKcs has been considered as a promising strategy of exploring novel radiosensitizers and killing agents of cancer cells. Combining DNA-PKcs inhibitors with radiotherapy can effectively enhance the efficacy of radiotherapy, offering more possibilities for cancer therapy.
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Affiliation(s)
- Xiaoqiao Yue
- School of Public Health, University of South China, Hengyang, China.,Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Chenjun Bai
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Dafei Xie
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
| | - Teng Ma
- Department of Cellular and Molecular Biology, Beijing Chest Hospital, Capital Medical University/Beijing Tuberculosis and Thoracic Tumor Research Institute, Beijing, China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing, China
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Hu C, Bugbee T, Gamez M, Wallace NA. Beta Human Papillomavirus 8E6 Attenuates Non-Homologous End Joining by Hindering DNA-PKcs Activity. Cancers (Basel) 2020; 12:cancers12092356. [PMID: 32825402 PMCID: PMC7564021 DOI: 10.3390/cancers12092356] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2020] [Revised: 08/15/2020] [Accepted: 08/18/2020] [Indexed: 12/20/2022] Open
Abstract
Cutaneous viral infections occur in a background of near continual exposure to environmental genotoxins, like UV radiation in sunlight. Failure to repair damaged DNA is an established driver of tumorigenesis and substantial cellular resources are devoted to repairing DNA lesions. Beta-human papillomaviruses (β-HPVs) attenuate DNA repair signaling. However, their role in human disease is unclear. Some have proposed that β-HPV promotes tumorigenesis, while others suggest that β-HPV protects against skin cancer. Most of the molecular evidence that β-HPV impairs DNA repair has been gained via characterization of the E6 protein from β-HPV 8 (β-HPV 8E6). Moreover, β-HPV 8E6 hinders DNA repair by binding and destabilizing p300, a transcription factor for multiple DNA repair genes. By reducing p300 availability, β-HPV 8E6 attenuates a major double strand DNA break (DSB) repair pathway, homologous recombination. Here, β-HPV 8E6 impairs another DSB repair pathway, non-homologous end joining (NHEJ). Specifically, β-HPV 8E6 acts by attenuating DNA-dependent protein kinase (DNA-PK) activity, a critical NHEJ kinase. This includes DNA-PK activation and the downstream of steps in the pathway associated with DNA-PK activity. Notably, β-HPV 8E6 inhibits NHEJ through p300 dependent and independent means. Together, these data expand the known genome destabilizing capabilities of β-HPV 8E6.
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Affiliation(s)
- Changkun Hu
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA; (C.H.); (T.B.)
| | - Taylor Bugbee
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA; (C.H.); (T.B.)
| | - Monica Gamez
- Bristol Medical School, Translational Health Sciences, University of Bristol, Bristol BS1 3NY, UK;
| | - Nicholas A. Wallace
- Division of Biology, Kansas State University, Manhattan, KS 66506, USA; (C.H.); (T.B.)
- Correspondence:
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15
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Gao SS, Guan H, Yan S, Hu S, Song M, Guo ZP, Xie DF, Liu Y, Liu X, Zhang S, Zhou PK. TIP60 K430 SUMOylation attenuates its interaction with DNA-PKcs in S-phase cells: Facilitating homologous recombination and emerging target for cancer therapy. SCIENCE ADVANCES 2020; 6:eaba7822. [PMID: 32832608 PMCID: PMC7439314 DOI: 10.1126/sciadv.aba7822] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 06/01/2020] [Indexed: 05/12/2023]
Abstract
Nonhomologous end joining (NHEJ) and homologous recombination (HR) are major repair pathways of DNA double-strand breaks (DSBs). The pathway choice of HR and NHEJ is tightly regulated in cellular response to DNA damage. Here, we demonstrate that the interaction of TIP60 with DNA-PKcs is attenuated specifically in S phase, which facilitates HR pathway activation. SUMO2 modification of TIP60 K430 mediated by PISA4 E3 ligase blocks its interaction with DNA-PKcs, whereas TIP60 K430R mutation recovers its interaction with DNA-PKcs, which results in abnormally increased phosphorylation of DNA-PKcs S2056 in S phase and marked inhibition of HR efficiency, but barely affects NHEJ activity. TIP60 K430R mutant cancer cells are more sensitive to radiation and PARP inhibitors in cancer cell killing and tumor growth inhibition. Collectively, coordinated regulation of TIP60 and DNA-PKcs facilitates HR pathway choice in S-phase cells. TIP60 K430R mutant is a potential target of radiation and PARPi cancer therapy.
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Affiliation(s)
- Shan-Shan Gao
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Hua Guan
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Shuang Yan
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
- Institute for Environmental Medicine and Radiation Hygiene, School of Public Health, University of South China, Hengyang, Hunan Province 421001, P. R. China
| | - Sai Hu
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Man Song
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Zong-Pei Guo
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Da-Fei Xie
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Yike Liu
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou 511436, P. R. China
| | - Xiaodan Liu
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Shimeng Zhang
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, Beijing 100850, P. R. China
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory Disease, Guangzhou Medical University, Xinzao, Panyu District, Guangzhou 511436, P. R. China
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16
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Forrer Charlier C, Martins RAP. Protective Mechanisms Against DNA Replication Stress in the Nervous System. Genes (Basel) 2020; 11:E730. [PMID: 32630049 PMCID: PMC7397197 DOI: 10.3390/genes11070730] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 06/25/2020] [Accepted: 06/25/2020] [Indexed: 02/06/2023] Open
Abstract
The precise replication of DNA and the successful segregation of chromosomes are essential for the faithful transmission of genetic information during the cell cycle. Alterations in the dynamics of genome replication, also referred to as DNA replication stress, may lead to DNA damage and, consequently, mutations and chromosomal rearrangements. Extensive research has revealed that DNA replication stress drives genome instability during tumorigenesis. Over decades, genetic studies of inherited syndromes have established a connection between the mutations in genes required for proper DNA repair/DNA damage responses and neurological diseases. It is becoming clear that both the prevention and the responses to replication stress are particularly important for nervous system development and function. The accurate regulation of cell proliferation is key for the expansion of progenitor pools during central nervous system (CNS) development, adult neurogenesis, and regeneration. Moreover, DNA replication stress in glial cells regulates CNS tumorigenesis and plays a role in neurodegenerative diseases such as ataxia telangiectasia (A-T). Here, we review how replication stress generation and replication stress response (RSR) contribute to the CNS development, homeostasis, and disease. Both cell-autonomous mechanisms, as well as the evidence of RSR-mediated alterations of the cellular microenvironment in the nervous system, were discussed.
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Affiliation(s)
| | - Rodrigo A. P. Martins
- Programa de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro 21941-902, Brazil;
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17
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Huang RX, Zhou PK. DNA damage response signaling pathways and targets for radiotherapy sensitization in cancer. Signal Transduct Target Ther 2020; 5:60. [PMID: 32355263 PMCID: PMC7192953 DOI: 10.1038/s41392-020-0150-x] [Citation(s) in RCA: 480] [Impact Index Per Article: 120.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 02/20/2020] [Accepted: 03/16/2020] [Indexed: 12/19/2022] Open
Abstract
Radiotherapy is one of the most common countermeasures for treating a wide range of tumors. However, the radioresistance of cancer cells is still a major limitation for radiotherapy applications. Efforts are continuously ongoing to explore sensitizing targets and develop radiosensitizers for improving the outcomes of radiotherapy. DNA double-strand breaks are the most lethal lesions induced by ionizing radiation and can trigger a series of cellular DNA damage responses (DDRs), including those helping cells recover from radiation injuries, such as the activation of DNA damage sensing and early transduction pathways, cell cycle arrest, and DNA repair. Obviously, these protective DDRs confer tumor radioresistance. Targeting DDR signaling pathways has become an attractive strategy for overcoming tumor radioresistance, and some important advances and breakthroughs have already been achieved in recent years. On the basis of comprehensively reviewing the DDR signal pathways, we provide an update on the novel and promising druggable targets emerging from DDR pathways that can be exploited for radiosensitization. We further discuss recent advances identified from preclinical studies, current clinical trials, and clinical application of chemical inhibitors targeting key DDR proteins, including DNA-PKcs (DNA-dependent protein kinase, catalytic subunit), ATM/ATR (ataxia-telangiectasia mutated and Rad3-related), the MRN (MRE11-RAD50-NBS1) complex, the PARP (poly[ADP-ribose] polymerase) family, MDC1, Wee1, LIG4 (ligase IV), CDK1, BRCA1 (BRCA1 C terminal), CHK1, and HIF-1 (hypoxia-inducible factor-1). Challenges for ionizing radiation-induced signal transduction and targeted therapy are also discussed based on recent achievements in the biological field of radiotherapy.
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Affiliation(s)
- Rui-Xue Huang
- Department of Occupational and Environmental Health, Xiangya School of Public Health, Central South University, 410078, Changsha, People's Republic of China
| | - Ping-Kun Zhou
- Department of Radiation Biology, Beijing Key Laboratory for Radiobiology, Beijing Institute of Radiation Medicine, AMMS, 100850, Beijing, People's Republic of China.
- Institute for Chemical Carcinogenesis, State Key Laboratory of Respiratory, Guangzhou Medical University, 511436, Guangzhou, People's Republic of China.
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18
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Tarsounas M, Sung P. The antitumorigenic roles of BRCA1-BARD1 in DNA repair and replication. Nat Rev Mol Cell Biol 2020; 21:284-299. [PMID: 32094664 PMCID: PMC7204409 DOI: 10.1038/s41580-020-0218-z] [Citation(s) in RCA: 175] [Impact Index Per Article: 43.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2020] [Indexed: 11/09/2022]
Abstract
The tumour suppressor breast cancer type 1 susceptibility protein (BRCA1) promotes DNA double-strand break (DSB) repair by homologous recombination and protects DNA replication forks from attrition. BRCA1 partners with BRCA1-associated RING domain protein 1 (BARD1) and other tumour suppressor proteins to mediate the initial nucleolytic resection of DNA lesions and the recruitment and regulation of the recombinase RAD51. The discovery of the opposing functions of BRCA1 and the p53-binding protein 1 (53BP1)-associated complex in DNA resection sheds light on how BRCA1 influences the choice of homologous recombination over non-homologous end joining and potentially other mutagenic pathways of DSB repair. Understanding the functional crosstalk between BRCA1-BARD1 and its cofactors and antagonists will illuminate the molecular basis of cancers that arise from a deficiency or misregulation of chromosome damage repair and replication fork maintenance. Such knowledge will also be valuable for understanding acquired tumour resistance to poly(ADP-ribose) polymerase (PARP) inhibitors and other therapeutics and for the development of new treatments. In this Review, we discuss recent advances in elucidating the mechanisms by which BRCA1-BARD1 functions in DNA repair, replication fork maintenance and tumour suppression, and its therapeutic relevance.
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Affiliation(s)
- Madalena Tarsounas
- Genome Stability and Tumourigenesis Group, Oxford Institute for Radiation Oncology, Department of Oncology, University of Oxford, Oxford, UK.
| | - Patrick Sung
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center, San Antonio, TX, USA.
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19
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Structural biology of multicomponent assemblies in DNA double-strand-break repair through non-homologous end joining. Curr Opin Struct Biol 2020; 61:9-16. [DOI: 10.1016/j.sbi.2019.09.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 09/30/2019] [Indexed: 01/19/2023]
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20
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Abstract
DNA-dependent protein kinase (DNA-PK) is involved in many cellular pathways. It has a key role in the cellular response to DNA damage, in the repair of DNA double-strand break (DNA-DSBs) and as a consequence an important role in maintaining genomic integrity. In addition, DNA-PK has been shown to modulate transcription, to be involved in the development of the immune system and to protect telomeres. These pleotropic involvements and the fact that its expression is de-regulated in cancer have made DNA-PK an intriguing therapeutic target in cancer therapy, especially when combined with agents causing DNA-DSBs such as topoisomerase II inhibitors and ionizing radiation. Different small molecule inhibitors of DNA-PK have been recently synthesized and some are now being tested in clinical trials. This review discusses what is known about DNA-PK, its role in tumor biology, DNA repair and cancer therapy and critically discusses its inhibition as a potential therapeutic approach.
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Affiliation(s)
- Giovanna Damia
- Laboratory of Molecular Pharmacology, Department of Oncology, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milan, Italy.
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21
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Lu H, Saha J, Beckmann PJ, Hendrickson EA, Davis AJ. DNA-PKcs promotes chromatin decondensation to facilitate initiation of the DNA damage response. Nucleic Acids Res 2019; 47:9467-9479. [PMID: 31396623 PMCID: PMC6765147 DOI: 10.1093/nar/gkz694] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 07/29/2019] [Accepted: 07/31/2019] [Indexed: 11/14/2022] Open
Abstract
The DNA damage response (DDR) encompasses the cellular response to DNA double-stranded breaks (DSBs), and includes recognition of the DSB, recruitment of numerous factors to the DNA damage site, initiation of signaling cascades, chromatin remodeling, cell-cycle checkpoint activation, and repair of the DSB. Key drivers of the DDR are multiple members of the phosphatidylinositol 3-kinase-related kinase family, including ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related (ATR), and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). ATM and ATR modulate multiple portions of the DDR, but DNA-PKcs is believed to primarily function in the DSB repair pathway, non-homologous end joining. Utilizing a human cell line in which the kinase domain of DNA-PKcs is inactivated, we show here that DNA-PKcs kinase activity is required for the cellular response to DSBs immediately after their induction. Specifically, DNA-PKcs kinase activity initiates phosphorylation of the chromatin factors H2AX and KAP1 following ionizing radiation exposure and drives local chromatin decondensation near the DSB site. Furthermore, loss of DNA-PKcs kinase activity results in a marked decrease in the recruitment of numerous members of the DDR machinery to DSBs. Collectively, these results provide clear evidence that DNA-PKcs activity is pivotal for the initiation of the DDR.
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Affiliation(s)
- Huiming Lu
- Division of Molecular Radiation Biology, Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Janapriya Saha
- Division of Molecular Radiation Biology, Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Pauline J Beckmann
- 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
| | - Anthony J Davis
- Division of Molecular Radiation Biology, Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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22
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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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23
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Mohiuddin IS, Kang MH. DNA-PK as an Emerging Therapeutic Target in Cancer. Front Oncol 2019; 9:635. [PMID: 31380275 PMCID: PMC6650781 DOI: 10.3389/fonc.2019.00635] [Citation(s) in RCA: 122] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 06/27/2019] [Indexed: 12/21/2022] Open
Abstract
The DNA-dependent protein kinase (DNA-PK) plays an instrumental role in the overall survival and proliferation of cells. As a member of the phosphatidylinositol 3-kinase-related kinase (PIKK) family, DNA-PK is best known as a mediator of the cellular response to DNA damage. In this context, DNA-PK has emerged as an intriguing therapeutic target in the treatment of a variety of cancers, especially when used in conjunction with genotoxic chemotherapy or ionizing radiation. Beyond the DNA damage response, DNA-PK activity is necessary for multiple cellular functions, including the regulation of transcription, progression of the cell cycle, and in the maintenance of telomeres. Here, we review what is currently known about DNA-PK regarding its structure and established roles in DNA repair. We also discuss its lesser-known functions, the pharmacotherapies inhibiting its function in DNA repair, and its potential as a therapeutic target in a broader context.
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Affiliation(s)
- Ismail S Mohiuddin
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
| | - Min H Kang
- Cancer Center, Department of Pediatrics, Pharmacology and Neuroscience, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX, United States
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24
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Multicomponent assemblies in DNA-double-strand break repair by NHEJ. Curr Opin Struct Biol 2019; 55:154-160. [DOI: 10.1016/j.sbi.2019.03.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 03/06/2019] [Accepted: 03/27/2019] [Indexed: 11/17/2022]
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25
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Abstract
Known for its tumor suppressor activity in breast and ovarian cancers, the breast cancer 1 susceptibility gene (Brca1) is involved in a variety of cellular pathways including DNA repair, antioxidant signaling, apoptosis, and cell cycle regulation. BRCA1 can translocate between the cytoplasm and nucleus to perform its various roles. Herein is a procedure for measuring BRCA1 protein levels in the whole cell lysate (WCL), as well as in the nuclear (N) and cytoplasmic (C) fractions of mouse tissues at different gestational ages. The method employs multiple loading controls to ensure proper separation of fractions and a total protein stain for more consistent comparisons of dissimilar samples. This method is useful for identifying BRCA1 deficiencies and localization in a variety of research fields, including development, neurodegeneration, and cancer.
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Affiliation(s)
- Danielle M Drake
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada
| | - Peter G Wells
- Department of Pharmaceutical Sciences and Centre for Pharmaceutical Oncology, University of Toronto, Toronto, ON, Canada.
- Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada.
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26
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Cell cycle-dependent phosphorylation regulates RECQL4 pathway choice and ubiquitination in DNA double-strand break repair. Nat Commun 2017; 8:2039. [PMID: 29229926 PMCID: PMC5725494 DOI: 10.1038/s41467-017-02146-3] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 11/08/2017] [Indexed: 12/29/2022] Open
Abstract
Pathway choice within DNA double-strand break (DSB) repair is a tightly regulated process to maintain genome integrity. RECQL4, deficient in Rothmund-Thomson Syndrome, promotes the two major DSB repair pathways, non-homologous end joining (NHEJ) and homologous recombination (HR). Here we report that RECQL4 promotes and coordinates NHEJ and HR in different cell cycle phases. RECQL4 interacts with Ku70 to promote NHEJ in G1 when overall cyclin-dependent kinase (CDK) activity is low. During S/G2 phases, CDK1 and CDK2 (CDK1/2) phosphorylate RECQL4 on serines 89 and 251, enhancing MRE11/RECQL4 interaction and RECQL4 recruitment to DSBs. After phosphorylation, RECQL4 is ubiquitinated by the DDB1-CUL4A E3 ubiquitin ligase, which facilitates its accumulation at DSBs. Phosphorylation of RECQL4 stimulates its helicase activity, promotes DNA end resection, increases HR and cell survival after ionizing radiation, and prevents cellular senescence. Collectively, we propose that RECQL4 modulates the pathway choice of NHEJ and HR in a cell cycle-dependent manner. DNA double-strand break (DSB) repair is a tightly regulated process that can occur via non-homologous end joining (NHEJ) or homologous recombination (HR). Here, the authors investigate how RECQL4 modulates DSB repair pathway choice by differentially regulating NHEJ and HR in a cell cycle-dependent manner.
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27
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Sidorova J. A game of substrates: replication fork remodeling and its roles in genome stability and chemo-resistance. Cell Stress 2017; 1:115-133. [PMID: 29355244 PMCID: PMC5771654 DOI: 10.15698/cst2017.12.114] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2017] [Revised: 11/27/2017] [Accepted: 11/29/2017] [Indexed: 01/06/2023] Open
Abstract
During the hours that human cells spend in the DNA synthesis (S) phase of the cell cycle, they may encounter adversities such as DNA damage or shortage of nucleotides. Under these stresses, replication forks in DNA may experience slowing, stalling, and breakage. Fork remodeling mechanisms, which stabilize slow or stalled replication forks and ensure their ability to continue or resume replication, protect cells from genomic instability and carcinogenesis. Fork remodeling includes DNA strand exchanges that result in annealing of newly synthesized strands (fork reversal), controlled DNA resection, and cleavage of DNA strands. Defects in major tumor suppressor genes BRCA1 and BRCA2, and a subset of the Fanconi Anemia genes have been shown to result in deregulation in fork remodeling, and most prominently, loss of kilobases of nascent DNA from stalled replication forks. This phenomenon has recently gained spotlight as a potential marker and mediator of chemo-sensitivity in cancer cells and, conversely, its suppression - as a hallmark of acquired chemo-resistance. Moreover, nascent strand degradation at forks is now known to also trigger innate immune response to self-DNA. An increasingly sophisticated molecular description of these events now points at a combination of unbalanced fork reversal and end-resection as a root cause, yet also reveals the multi-layered complexity and heterogeneity of the underlying processes in normal and cancer cells.
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Affiliation(s)
- Julia Sidorova
- Department of Pathology, University of Washington, Seattle, Washington, USA
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PARI Regulates Stalled Replication Fork Processing To Maintain Genome Stability upon Replication Stress in Mice. Mol Cell Biol 2017; 37:MCB.00117-17. [PMID: 28894029 DOI: 10.1128/mcb.00117-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 09/07/2017] [Indexed: 12/14/2022] Open
Abstract
DNA replication is frequently perturbed by intrinsic, as well as extrinsic, genotoxic stress. At damaged forks, DNA replication and repair activities require proper coordination to maintain genome integrity. We show here that PARI antirecombinase plays an essential role in modulating the initial response to replication stress in mice. PARI is functionally dormant at replisomes during normal replication, but upon replication stress, it enhances nascent-strand shortening that is regulated by RAD51 and MRE11. PARI then promotes double-strand break induction, followed by new origin firing instead of replication restart. Such PARI function is apparently obstructive to replication but is nonetheless physiologically required for chromosome stability in vivo and ex vivo Of note, Pari-deficient embryonic stem cells exhibit spontaneous chromosome instability, which is attenuated by differentiation induction, suggesting that pluripotent stem cells have a preferential requirement for PARI that acts against endogenous replication stress. PARI is a latent modulator of stalled fork processing, which is required for stable genome inheritance under both endogenous and exogenous replication stress in mice.
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Zhu S, Fisher LA, Bessho T, Peng A. Protein phosphatase 1 and phosphatase 1 nuclear targeting subunit-dependent regulation of DNA-dependent protein kinase and non-homologous end joining. Nucleic Acids Res 2017; 45:10583-10594. [PMID: 28985363 PMCID: PMC5737533 DOI: 10.1093/nar/gkx686] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 07/28/2017] [Indexed: 12/29/2022] Open
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a key role in mediating non-homologous end joining (NHEJ), a major repair pathway for DNA double-strand breaks (DSBs). The activation, function and dynamics of DNA-PKcs is regulated largely by its reversible phosphorylation at numerous residues, many of which are targeted by DNA-PKcs itself. Interestingly, these DNA-PKcs phosphorylation sites function in a distinct, and sometimes opposing manner, suggesting that they are differentially regulated via complex actions of both kinases and phosphatases. In this study we identified several phosphatase subunits as potential DSB-associated proteins. In particular, protein phosphatase 1 (PP1) is recruited to a DSB-mimicking substrate in Xenopus egg extracts and sites of laser microirradiation in human cells. Depletion of PP1 impairs NHEJ in both Xenopus egg extracts and human cells. PP1 binds multiple motifs of DNA-PKcs, regulates DNA-PKcs phosphorylation, and is required for DNA-PKcs activation after DNA damage. Interestingly, phosphatase 1 nuclear targeting subunit (PNUTS), an inhibitory regulator of PP1, is also recruited to DNA damage sites to promote NHEJ. PNUTS associates with the DNA-PK complex and is required for DNA-PKcs phosphorylation at Ser-2056 and Thr-2609. Thus, PNUTS and PP1 together fine-tune the dynamic phosphorylation of DNA-PKcs after DNA damage to mediate NHEJ.
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Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Laura A Fisher
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Tadayoshi Bessho
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
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Abramenkovs A, Stenerlöw B. Measurement of DNA-Dependent Protein Kinase Phosphorylation Using Flow Cytometry Provides a Reliable Estimate of DNA Repair Capacity. Radiat Res 2017; 188:597-604. [PMID: 28952912 DOI: 10.1667/rr14693.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Uncontrolled generation of DNA double-strand breaks (DSBs) in cells is regarded as a highly toxic event that threatens cell survival. Radiation-induced DNA DSBs are commonly measured by pulsed-field gel electrophoresis, microscopic evaluation of accumulating DNA damage response proteins (e.g., 53BP1 or γ-H2AX) or flow cytometric analysis of γ-H2AX. The advantage of flow cytometric analysis is that DSB formation and repair can be studied in relationship to cell cycle phase or expression of other proteins. However, γ-H2AX is not able to monitor repair kinetics within the first 60 min postirradiation, a period when most DSBs undergo repair. A key protein in non-homologous end joining repair is the catalytic subunit of DNA-dependent protein kinase. Among several phosphorylation sites of DNA-dependent protein kinase, the threonine at position 2609 (T2609), which is phosphorylated by ataxia telangiectasia mutated (ATM) or DNA-dependent protein kinase catalytic subunit itself, activates the end processing of DSB. Using flow cytometry, we show here that phosphorylation at T2609 is faster in response to DSBs than γ-H2AX. Furthermore, flow cytometric analysis of T2609 resulted in a better representation of fast repair kinetics than analysis of γ-H2AX. In cells with reduced ligase IV activity, and wild-type cells where DNA-dependent protein kinase activity was inhibited, the reduced DSB repair capacity was observed by T2609 evaluation using flow cytometry. In conclusion, flow cytometric evaluation of DNA-dependent protein kinase T2609 can be used as a marker for early DSB repair and gives a better representation of early repair events than analysis of γ-H2AX.
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Affiliation(s)
- Andris Abramenkovs
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
| | - Bo Stenerlöw
- Department of Immunology, Genetics and Pathology, Rudbeck Laboratory, Uppsala University, SE-751 85 Uppsala, Sweden
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Abstract
DNA double-strand breaks (DSBs) are deleterious DNA lesions that must be properly repaired to maintain genome stability. Agents, generated both exogenously (environmental radiation, dental X-rays, etc.) and endogenously (reactive oxygen species, DNA replication, V(D)J recombination, etc.), induce numerous DSBs every day. To counter these DSBs, there are two major repair pathways in mammalian cells, nonhomologous end joining (NHEJ) and homologous recombination (HR). NHEJ directly mediates the religation of the broken DNA molecule and is active in all phases of the cell cycle. HR directs repair via the use of a homologous DNA sequence as a template and is primarily active in only S/G2 phases owing to the availability of a DNA template via a sister chromatid. As NHEJ and HR are active in multiple cell cycle phases, there is significant interest in how a cell chooses between the two DSB repair pathways. Therefore, it is essential to utilize assays to study DSB repair that can distinguish between the two DSB repair pathways and the different phases of the cell cycle. In this chapter, we describe methods to measure the contribution of DNA repair pathways in different phases of the cell cycle. These methods are simple, can be applied to most mammalian cell lines, and can be used as a broad utility to monitor cell cycle-dependent DSB repair.
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Sibanda BL, Chirgadze DY, Ascher DB, Blundell TL. DNA-PKcs structure suggests an allosteric mechanism modulating DNA double-strand break repair. Science 2017; 355:520-524. [DOI: 10.1126/science.aak9654] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 01/05/2017] [Indexed: 12/15/2022]
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Nagasawa H, Lin YF, Kato TA, Brogan JR, Shih HY, Kurimasa A, Bedford JS, Chen BPC, Little JB. Coordination of the Ser2056 and Thr2609 Clusters of DNA-PKcs in Regulating Gamma Rays and Extremely Low Fluencies of Alpha-Particle Irradiation to G 0/G 1 Phase Cells. Radiat Res 2017; 187:259-267. [PMID: 28118114 DOI: 10.1667/rr14679.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The catalytic subunit of DNA dependent protein kinase (DNA-PKcs) and its kinase activity are critical for mediation of non-homologous end-joining (NHEJ) of DNA double-strand breaks (DSB) in mammalian cells after gamma-ray irradiation. Additionally, DNA-PKcs phosphorylations at the T2609 cluster and the S2056 cluster also affect DSB repair and cellular sensitivity to gamma radiation. Previously we reported that phosphorylations within these two regions affect not only NHEJ but also homologous recombination repair (HRR) dependent DSB repair. In this study, we further examine phenotypic effects on cells bearing various combinations of mutations within either or both regions. Effects studied included cell killing as well as chromosomal aberration induction after 0.5-8 Gy gamma-ray irradiation delivered to synchronized cells during the G0/G1 phase of the cell cycle. Blocking phosphorylation within the T2609 cluster was most critical regarding sensitization and depended on the number of available phosphorylation sites. It was also especially interesting that only one substitution of alanine in each of the two clusters separately abolished the restoration of wild-type sensitivity by DNA-PKcs. Similar patterns were seen for induction of chromosomal aberrations, reflecting their connection to cell killing. To study possible change in coordination between HRR and NHEJ directed repair in these DNA-PKcs mutant cell lines, we compared the induction of sister chromatid exchanges (SCEs) by very low fluencies of alpha particles with mutant cells defective in the HRR pathway that is required for induction of SCEs. Levels of true SCEs induced by very low fluence of alpha-particle irradiation normally seen in wild-type cells were only slightly decreased in the S2056 cluster mutants, but were completely abolished in the T2609 cluster mutants and were indistinguishable from levels seen in HRR deficient cells. Again, a single substitution in the S2056 together with a single substitution in the T2609 cluster abolished SCE formation and thus also effectively interferes with HRR.
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Affiliation(s)
- Hatsumi Nagasawa
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Yu-Fen Lin
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Takamitsu A Kato
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - John R Brogan
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Hung-Ying Shih
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - Akihiro Kurimasa
- c Tohoku Medical and Pharmaceutical University, Sendai, Japan, 981-8558; and
| | - Joel S Bedford
- a Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523
| | - Benjamin P C Chen
- b Department of Radiation Oncology, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390
| | - John B Little
- d Department of Genetics and Complex Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
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Liang S, Esswein SR, Ochi T, Wu Q, Ascher DB, Chirgadze D, Sibanda BL, Blundell TL. Achieving selectivity in space and time with DNA double-strand-break response and repair: molecular stages and scaffolds come with strings attached. Struct Chem 2016. [DOI: 10.1007/s11224-016-0841-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Saha J, Davis AJ. Unsolved mystery: the role of BRCA1 in DNA end-joining. JOURNAL OF RADIATION RESEARCH 2016; 57 Suppl 1:i18-i24. [PMID: 27170701 PMCID: PMC4990114 DOI: 10.1093/jrr/rrw032] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 02/11/2016] [Accepted: 02/19/2016] [Indexed: 06/05/2023]
Abstract
Heritable mutations in the tumor suppressor gene BRCA1 increase a woman's lifetime risk of developing breast and ovarian cancer. BRCA1's tumor suppressor function is directly linked to its myriad of functions in the cellular response to DNA double-strand breaks (DSBs). BRCA1 interacts with an extensive array of DNA damage responsive proteins and plays important roles in DSB repair, mediated by the homologous recombination pathway, and in the activation of cell cycle checkpoints. However, the role of BRCA1 in the other two DSB repair pathways, classical non-homologous end-joining (C-NHEJ) and alternative NHEJ (A-NHEJ), remains unclear. In this review, we will discuss the current literature on BRCA1's potential role(s) in modulating both C-NHEJ and A-NHEJ. We also present a model showing that BRCA1 contributes to genomic maintenance by promoting precise DNA repair across all cell cycle phases via the direct modulation of DNA end-joining.
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Affiliation(s)
- Janapriya Saha
- Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390-9187, USA
| | - Anthony J Davis
- Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390-9187, USA
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Lysines 3241 and 3260 of DNA-PKcs are important for genomic stability and radioresistance. Biochem Biophys Res Commun 2016; 477:235-40. [PMID: 27297111 DOI: 10.1016/j.bbrc.2016.06.048] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 06/09/2016] [Indexed: 11/22/2022]
Abstract
DNA-dependent protein kinase (DNA-PK) is a serine/threonine kinase that plays an essential role in the repair of DNA double-strand breaks (DSBs) in the non-homologous end-joining (NHEJ) pathway. The DNA-PK holoenzyme consists of a catalytic subunit (DNA-PKcs) and DNA-binding subunit (Ku70/80, Ku). Ku is a molecular sensor for double-stranded DNA and once bound to DSB ends it recruits DNA-PKcs to the DSB site. Subsequently, DNA-PKcs is activated and heavily phosphorylated, with these phosphorylations modulating DNA-PKcs. Although phosphorylation of DNA-PKcs is well studied, other post-translational modifications of DNA-PKcs are not. In this study, we aimed to determine if acetylation of DNA-PKcs regulates DNA-PKcs-dependent DSB repair. We report that DNA-PKcs is acetylated in vivo and identified two putative acetylation sites, lysine residues 3241 and 3260. Mutating these sites to block potential acetylation results in increased radiosensitive, a slight decrease in DSB repair capacity as assessed by γH2AX resolution, and increased chromosomal aberrations, especially quadriradial chromosomes. Together, our results provide evidence that acetylation potentially regulates DNA-PKcs.
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Lee KJ, Saha J, Sun J, Fattah KR, Wang SC, Jakob B, Chi L, Wang SY, Taucher-Scholz G, Davis AJ, Chen DJ. Phosphorylation of Ku dictates DNA double-strand break (DSB) repair pathway choice in S phase. Nucleic Acids Res 2015; 44:1732-45. [PMID: 26712563 PMCID: PMC4770226 DOI: 10.1093/nar/gkv1499] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/11/2015] [Indexed: 12/16/2022] Open
Abstract
Multiple DNA double-strand break (DSB) repair pathways are active in S phase of the cell cycle; however, DSBs are primarily repaired by homologous recombination (HR) in this cell cycle phase. As the non-homologous end-joining (NHEJ) factor, Ku70/80 (Ku), is quickly recruited to DSBs in S phase, we hypothesized that an orchestrated mechanism modulates pathway choice between HR and NHEJ via displacement of the Ku heterodimer from DSBs to allow HR. Here, we provide evidence that phosphorylation at a cluster of sites in the junction of the pillar and bridge regions of Ku70 mediates the dissociation of Ku from DSBs. Mimicking phosphorylation at these sites reduces Ku's affinity for DSB ends, suggesting that phosphorylation of Ku70 induces a conformational change responsible for the dissociation of the Ku heterodimer from DNA ends. Ablating phosphorylation of Ku70 leads to the sustained retention of Ku at DSBs, resulting in a significant decrease in DNA end resection and HR, specifically in S phase. This decrease in HR is specific as these phosphorylation sites are not required for NHEJ. Our results demonstrate that the phosphorylation-mediated dissociation of Ku70/80 from DSBs frees DNA ends, allowing the initiation of HR in S phase and providing a mechanism of DSB repair pathway choice in mammalian cells.
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Affiliation(s)
- Kyung-Jong Lee
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Janapriya Saha
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Jingxin Sun
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Kazi R Fattah
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Shu-Chi Wang
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Burkhard Jakob
- Department of Biophysics; GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Linfeng Chi
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Shih-Ya Wang
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - Gisela Taucher-Scholz
- Department of Biophysics; GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, Darmstadt, Germany
| | - Anthony J Davis
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
| | - David J Chen
- Division of Molecular Radiation Biology, Department of Radiation Oncology, University of Texas Southwestern Medical Center, 2201 Inwood Rd, Dallas, Texas 75390, USA
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Hamada N, Fujimichi Y. Role of carcinogenesis related mechanisms in cataractogenesis and its implications for ionizing radiation cataractogenesis. Cancer Lett 2015; 368:262-74. [DOI: 10.1016/j.canlet.2015.02.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 12/20/2022]
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Yang Y, Liu Z, Wang F, Temviriyanukul P, Ma X, Tu Y, Lv L, Lin YF, Huang M, Zhang T, Pei H, Chen BPC, Jansen JG, de Wind N, Fischhaber PL, Friedberg EC, Tang TS, Guo C. FANCD2 and REV1 cooperate in the protection of nascent DNA strands in response to replication stress. Nucleic Acids Res 2015; 43:8325-39. [PMID: 26187992 PMCID: PMC4787816 DOI: 10.1093/nar/gkv737] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2015] [Accepted: 07/08/2015] [Indexed: 12/12/2022] Open
Abstract
REV1 is a eukaryotic member of the Y-family of DNA polymerases involved in translesion DNA synthesis and genome mutagenesis. Recently, REV1 is also found to function in homologous recombination. However, it remains unclear how REV1 is recruited to the sites where homologous recombination is processed. Here, we report that loss of mammalian REV1 results in a specific defect in replication-associated gene conversion. We found that REV1 is targeted to laser-induced DNA damage stripes in a manner dependent on its ubiquitin-binding motifs, on RAD18, and on monoubiquitinated FANCD2 (FANCD2-mUb) that associates with REV1. Expression of a FANCD2-Ub chimeric protein in RAD18-depleted cells enhances REV1 assembly at laser-damaged sites, suggesting that FANCD2-mUb functions downstream of RAD18 to recruit REV1 to DNA breaks. Consistent with this suggestion we found that REV1 and FANCD2 are epistatic with respect to sensitivity to the double-strand break-inducer camptothecin. REV1 enrichment at DNA damage stripes also partially depends on BRCA1 and BRCA2, components of the FANCD2/BRCA supercomplex. Intriguingly, analogous to FANCD2-mUb and BRCA1/BRCA2, REV1 plays an unexpected role in protecting nascent replication tracts from degradation by stabilizing RAD51 filaments. Collectively these data suggest that REV1 plays multiple roles at stalled replication forks in response to replication stress.
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Affiliation(s)
- Yeran Yang
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhenbo Liu
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Fengli Wang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Piya Temviriyanukul
- Department of Human Genetics, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Xiaolu Ma
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yingfeng Tu
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Lingna Lv
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yu-Fen Lin
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Min Huang
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Ting Zhang
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Huadong Pei
- Beijing Proteome Research Center, Beijing Institute of Radiation Medicine, Beijing 102206, China
| | - Benjamin P C Chen
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Jacob G Jansen
- Department of Human Genetics, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Niels de Wind
- Department of Human Genetics, Leiden University Medical Center, 2300 RC, Leiden, The Netherlands
| | - Paula L Fischhaber
- Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262, USA
| | - Errol C Friedberg
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Tie-Shan Tang
- State Key Laboratory of Membrane Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Caixia Guo
- Key Laboratory of Genomics and Precision Medicine, China Gastrointestinal Cancer Research Center, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
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Tu Z, Xu B, Qu C, Tao Y, Chen C, Hua W, Feng G, Chang H, Liu Z, Li G, Jiang C, Yi W, Zeng M, Xia Y. BRCC3 acts as a prognostic marker in nasopharyngeal carcinoma patients treated with radiotherapy and mediates radiation resistance in vitro. Radiat Oncol 2015; 10:123. [PMID: 26024915 PMCID: PMC4511524 DOI: 10.1186/s13014-015-0427-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 05/24/2015] [Indexed: 11/11/2022] Open
Abstract
Background BRCC3 has been found to be aberrantly expressed in breast tumors and involved in DNA damage response. The contribution of BRCC3 to nasopharyngeal carcinoma prognosis and radiosensitivity is still unclear. Methods Immunohistochemical analysis of BRCC3 was carried out in 100 nasopharyngeal carcinoma tissues, and the protein level was correlated to patient survival. BRCC3 expression of nasopharyngeal carcinoma cell lines was determined by Western-blotting and real-time PCR. Additionally, the effects of BRCC3 knockdown on nasopharyngeal carcinoma cell clongenic survival, DNA damage repair, and cell cycle distribution after irradiation was assessed. Results The BRCC3 protein level was inversely correlated with nasopharyngeal carcinoma patient overall survival (P < 0.001) and 3-year loco-regional relapse-free survival (P = 0.034). Multivariate analysis demonstrated that BRCC3 expression was an independent prognostic factor (P = 0.010). The expression of BRCC3 was much higher in radioresistant nasopharyngeal carcinoma cells than in radiosensitive cells. Knockdown of BRCC3 increased the cell survival fraction, attenuated DNA damage repair and resulted in G2/M cell cycle arrest in radioresistant NPC cells. Conclusions High BRCC3 expression in nasopharyngeal carcinoma patients is associated with poor survival. BRCC3 knockdown could abate the radioresistance in nasopharyngeal carcinoma cells. These findings suggest the utility of BRCC3 as a prognostic biomarker and novel target for nasopharyngeal carcinoma.
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Affiliation(s)
- Ziwei Tu
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Bingqing Xu
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Chen Qu
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Yalan Tao
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Chen Chen
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Wenfeng Hua
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Guokai Feng
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Hui Chang
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China.
| | - Zhigang Liu
- Department of Radiation Oncology, Hunan Cancer Hospital, The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, Hunan, People's Republic of China.
| | - Guo Li
- Department of Radiation Oncology, Affiliated Tumor Hospital, Guangzhou Medical University, Guangzhou, Guangdong, People's Republic of China.
| | - Changbin Jiang
- Department of Radiation Oncology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People's Republic of China.
| | - Wei Yi
- Department of Radiation Oncology, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, People's Republic of China.
| | - Musheng Zeng
- State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
| | - Yunfei Xia
- Department of Radiation Oncology, Sun Yat-Sen University Cancer Center, No. 651, Dongfeng East Road, Guangzhou, 510060, People's Republic of China. .,State Key Laboratory of Oncology in South China, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong, People's Republic of China.
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Wu Q, Jubb H, Blundell TL. Phosphopeptide interactions with BRCA1 BRCT domains: More than just a motif. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2015; 117:143-148. [PMID: 25701377 PMCID: PMC4728184 DOI: 10.1016/j.pbiomolbio.2015.02.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Revised: 01/05/2015] [Accepted: 02/10/2015] [Indexed: 01/15/2023]
Abstract
BRCA1 BRCT domains function as phosphoprotein-binding modules for recognition of the phosphorylated protein-sequence motif pSXXF. While the motif interaction interface provides strong anchor points for binding, protein regions outside the motif have recently been found to be important for binding affinity. In this review, we compare the available structural data for BRCA1 BRCT domains in complex with phosphopeptides in order to gain a more complete understanding of the interaction between phosphopeptides and BRCA1-BRCT domains.
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Affiliation(s)
- Qian Wu
- Department of Biochemistry, 80 Tennis Court Road, University of Cambridge, CB2 1GA, Cambridge, United Kingdom.
| | - Harry Jubb
- Department of Biochemistry, 80 Tennis Court Road, University of Cambridge, CB2 1GA, Cambridge, United Kingdom
| | - Tom L Blundell
- Department of Biochemistry, 80 Tennis Court Road, University of Cambridge, CB2 1GA, Cambridge, United Kingdom
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