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Dylgjeri E, Knudsen KE. DNA-PKcs: A Targetable Protumorigenic Protein Kinase. Cancer Res 2022; 82:523-533. [PMID: 34893509 PMCID: PMC9306356 DOI: 10.1158/0008-5472.can-21-1756] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 08/17/2021] [Accepted: 11/10/2021] [Indexed: 01/07/2023]
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a pleiotropic protein kinase that plays critical roles in cellular processes fundamental to cancer. DNA-PKcs expression and activity are frequently deregulated in multiple hematologic and solid tumors and have been tightly linked to poor outcome. Given the potentially influential role of DNA-PKcs in cancer development and progression, therapeutic targeting of this kinase is being tested in preclinical and clinical settings. This review summarizes the latest advances in the field, providing a comprehensive discussion of DNA-PKcs functions in cancer and an update on the clinical assessment of DNA-PK inhibitors in cancer therapy.
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Affiliation(s)
- Emanuela Dylgjeri
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania
| | - Karen E. Knudsen
- Department of Cancer Biology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Sidney Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Medical Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Urology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Department of Radiation Oncology, Thomas Jefferson University, Philadelphia, Pennsylvania.,Corresponding Author: Karen E. Knudsen, Thomas Jefferson University, 233 South 10th Street, BLSB 1050, Philadelphia, PA 19107. Phone: 215-503-5692; E-mail:
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2
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Liu L, Dai X, Yin S, Liu P, Hill EG, Wei W, Gan W. DNA-PK promotes activation of the survival kinase AKT in response to DNA damage through an mTORC2-ECT2 pathway. Sci Signal 2022; 15:eabh2290. [PMID: 34982576 DOI: 10.1126/scisignal.abh2290] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Liu Liu
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.,Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Xiaoming Dai
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Shasha Yin
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.,Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Pengda Liu
- Lineberger Comprehensive Cancer Center and Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Elizabeth G Hill
- Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA.,Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC 29425, USA
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | - Wenjian Gan
- Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425, USA.,Hollings Cancer Center, Medical University of South Carolina, Charleston, SC 29425, USA
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3
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Anisenko A, Kan M, Shadrina O, Brattseva A, Gottikh M. Phosphorylation Targets of DNA-PK and Their Role in HIV-1 Replication. Cells 2020; 9:E1907. [PMID: 32824372 PMCID: PMC7464883 DOI: 10.3390/cells9081907] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 08/13/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023] Open
Abstract
The DNA dependent protein kinase (DNA-PK) is a trimeric nuclear complex consisting of a large protein kinase and the Ku heterodimer. The kinase activity of DNA-PK is required for efficient repair of DNA double-strand breaks (DSB) by non-homologous end joining (NHEJ). We also showed that the kinase activity of DNA-PK is essential for post-integrational DNA repair in the case of HIV-1 infection. Besides, DNA-PK is known to participate in such cellular processes as protection of mammalian telomeres, transcription, and some others where the need for its phosphorylating activity is not clearly elucidated. We carried out a systematic search and analysis of DNA-PK targets described in the literature and identified 67 unique DNA-PK targets phosphorylated in response to various in vitro and/or in vivo stimuli. A functional enrichment analysis of DNA-PK targets and determination of protein-protein associations among them were performed. For 27 proteins from these 67 DNA-PK targets, their participation in the HIV-1 life cycle was demonstrated. This information may be useful for studying the functioning of DNA-PK in various cellular processes, as well as in various stages of HIV-1 replication.
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Affiliation(s)
- Andrey Anisenko
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Kan
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Olga Shadrina
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Anna Brattseva
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119234, Russia;; (M.K.); (A.B.)
| | - Marina Gottikh
- Chemistry Department and Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119234, Russia; (O.S.); (M.G.)
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Abstract
PURPOSE OF REVIEW Antiphospholipid syndrome (APS) is a rare heterogenous disorder associated with the presence of antiphospholipid antibodies and can present in a wide variety of clinical manifestations including thrombosis and pregnancy complications. Although the etiology of APS remains poorly understood, there is strong support for considering APS as a complex genetic disease in which multiple genetic risk factors, in conjunction with environmental factors, affect its onset, progression, and severity. Here, we provide a comprehensive review of the current knowledge of the genetic basis of APS, which remains in its infancy. RECENT FINDINGS Most genetic studies to date in APS were performed in small cohorts of patients. As a result, only few genetic associations reported are convincing. Several reports suggested genetic associations with HLA class II alleles in APS, and only two genetic loci outside of the HLA region (STAT4 and C1D) reached the threshold for genome-wide level of significance (P < 5 × 10-8). In this review, we also shed light on the genetic differences among the diverse clinical subsets of APS and briefly discuss the role that DNA methylation changes might play in the pathophysiology of this disease. The genetic basis of APS remains poorly characterized. Larger collaborative multicenter studies using well-characterized patients are needed to comprehensively understand the role of genetic susceptibility in APS.
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5
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George VC, Ansari SA, Chelakkot VS, Chelakkot AL, Chelakkot C, Menon V, Ramadan W, Ethiraj KR, El-Awady R, Mantso T, Mitsiogianni M, Panagiotidis MI, Dellaire G, Vasantha Rupasinghe HP. DNA-dependent protein kinase: Epigenetic alterations and the role in genomic stability of cancer. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2018; 780:92-105. [PMID: 31395353 DOI: 10.1016/j.mrrev.2018.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 06/13/2018] [Indexed: 12/28/2022]
Abstract
DNA-dependent protein kinase (DNA-PK), a member of phosphatidylinositol-kinase family, is a key protein in mammalian DNA double-strand break (DSB) repair that helps to maintain genomic integrity. DNA-PK also plays a central role in immune cell development and protects telomerase during cellular aging. Epigenetic deregulation due to endogenous and exogenous factors may affect the normal function of DNA-PK, which in turn could impair DNA repair and contribute to genomic instability. Recent studies implicate a role for epigenetics in the regulation of DNA-PK expression in normal and cancer cells, which may impact cancer progression and metastasis as well as provide opportunities for treatment and use of DNA-PK as a novel cancer biomarker. In addition, several small molecules and biological agents have been recently identified that can inhibit DNA-PK function or expression, and thus hold promise for cancer treatments. This review discusses the impact of epigenetic alterations and the expression of DNA-PK in relation to the DNA repair mechanisms with a focus on its differential levels in normal and cancer cells.
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Affiliation(s)
- Vazhappilly Cijo George
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Shabbir Ahmed Ansari
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Vipin Shankar Chelakkot
- Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland, Canada
| | | | - Chaithanya Chelakkot
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, Republic of Korea
| | - Varsha Menon
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates
| | - Wafaa Ramadan
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Medicine, University of Sharjah, Sharjah, United Arab Emirates
| | | | - Raafat El-Awady
- Sharjah Institute for Medical Research, University of Sharjah, Sharjah, United Arab Emirates; College of Pharmacy, University of Sharjah, Sharjah, United Arab Emirates; Cancer Biology Department, National Cancer Institute and College of Medicine, Cairo University, Cairo, Egypt
| | - Theodora Mantso
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Melina Mitsiogianni
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Mihalis I Panagiotidis
- Department of Applied Sciences, Faculty of Health & Life Sciences, Northumbria University, Newcastle upon Tyne, United Kingdom
| | - Graham Dellaire
- Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada
| | - H P Vasantha Rupasinghe
- Department of Plant, Food, and Environmental Sciences, Faculty of Agriculture, Dalhousie University, Truro, NS, Canada; Department of Pathology, Faculty of Medicine, Dalhousie University, Halifax, NS, Canada.
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Awwad SW, Abu-Zhayia ER, Guttmann-Raviv N, Ayoub N. NELF-E is recruited to DNA double-strand break sites to promote transcriptional repression and repair. EMBO Rep 2017; 18:745-764. [PMID: 28336775 PMCID: PMC5412775 DOI: 10.15252/embr.201643191] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 02/07/2017] [Accepted: 02/08/2017] [Indexed: 01/12/2023] Open
Abstract
Double-strand breaks (DSBs) trigger rapid and transient transcription pause to prevent collisions between repair and transcription machineries at damage sites. Little is known about the mechanisms that ensure transcriptional block after DNA damage. Here, we reveal a novel role of the negative elongation factor NELF in blocking transcription activity nearby DSBs. We show that NELF-E and NELF-A are rapidly recruited to DSB sites. Furthermore, NELF-E recruitment and its repressive activity are both required for switching off transcription at DSBs. Remarkably, using I-SceI endonuclease and CRISPR-Cas9 systems, we observe that NELF-E is preferentially recruited, in a PARP1-dependent manner, to DSBs induced upstream of transcriptionally active rather than inactive genes. Moreover, the presence of RNA polymerase II is a prerequisite for the preferential recruitment of NELF-E to DNA break sites. Additionally, we demonstrate that NELF-E is required for intact repair of DSBs. Altogether, our data identify the NELF complex as a new component in the DNA damage response.
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Affiliation(s)
- Samah W Awwad
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Enas R Abu-Zhayia
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Noga Guttmann-Raviv
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Nabieh Ayoub
- Department of Biology, Technion - Israel Institute of Technology, Haifa, Israel
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7
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Chen YJC, Wang HJ, Jauh GY. Dual Role of a SAS10/C1D Family Protein in Ribosomal RNA Gene Expression and Processing Is Essential for Reproduction in Arabidopsis thaliana. PLoS Genet 2016; 12:e1006408. [PMID: 27792779 PMCID: PMC5085252 DOI: 10.1371/journal.pgen.1006408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 10/06/2016] [Indexed: 12/20/2022] Open
Abstract
In eukaryotic cells, ribosomal RNAs (rRNAs) are transcribed, processed, and assembled with ribosomal proteins in the nucleolus. Regulatory mechanisms of rRNA gene (rDNA) transcription and processing remain elusive in plants, especially their connection to nucleolar organization. We performed an in silico screen for essential genes of unknown function in Arabidopsis thaliana and identified Thallo (THAL) encoding a SAS10/C1D family protein. THAL disruption caused enlarged nucleoli in arrested embryos, aberrant processing of precursor rRNAs at the 5' External Transcribed Spacer, and repression of the major rDNA variant (VAR1). THAL overexpression lines showed de-repression of VAR1 and overall reversed effects on rRNA processing sites. Strikingly, THAL overexpression also induced formation of multiple nucleoli per nucleus phenotypic of mutants of heterochromatin factors. THAL physically associated with histone chaperone Nucleolin 1 (NUC1), histone-binding NUC2, and histone demethylase Jumonji 14 (JMJ14) in bimolecular fluorescence complementation assay, suggesting that it participates in chromatin regulation. Furthermore, investigation of truncated THAL proteins revealed that the SAS10 C-terminal domain is likely important for its function in chromatin configuration. THAL also interacted with putative Small Subunit processome components, including previously unreported Arabidopsis homologue of yeast M Phase Phosphoprotein 10 (MPP10). Our results uncovering the dual role of THAL in transcription and processing events critical for proper rRNA biogenesis and nucleolar organization during reproduction are the first to define the function of SAS10/C1D family members in plants.
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Affiliation(s)
- Ying-Jiun C. Chen
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taichung, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung, Taiwan
| | - Huei-Jing Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
| | - Guang-Yuh Jauh
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taichung, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung, Taiwan
- * E-mail:
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8
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Jackson RA, Wu JS, Chen ES. C1D family proteins in coordinating RNA processing, chromosome condensation and DNA damage response. Cell Div 2016; 11:2. [PMID: 27030795 PMCID: PMC4812661 DOI: 10.1186/s13008-016-0014-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 02/22/2016] [Indexed: 12/02/2022] Open
Abstract
Research on the involvement of C1D and its yeast homologues Rrp47 (S. cerevisiae) and Cti1 (S. pombe) in DNA damage repair and RNA processing has remained mutually exclusive, with most studies predominantly concentrating on Rrp47. This review will look to reconcile the functions of these proteins in their involvement with the RNA exosome, in the regulation of chromatin architecture, and in the repair of DNA double-strand breaks, focusing on non-homologous end joining and homologous recombination. We propose that C1D is situated in a central position to maintain genomic stability at highly transcribed gene loci by coordinating these processes through the timely recruitment of relevant regulatory factors. In the event that the damage is beyond repair, C1D induces apoptosis in a p53-dependent manner.
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Affiliation(s)
- Rebecca A Jackson
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597 Singapore
| | - Jocelyn Shumei Wu
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597 Singapore
| | - Ee Sin Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117597 Singapore ; National University Health System (NUHS), Singapore, 119228 Singapore ; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, 119228 Singapore
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9
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The regulation and functions of the nuclear RNA exosome complex. Nat Rev Mol Cell Biol 2016; 17:227-39. [PMID: 26726035 DOI: 10.1038/nrm.2015.15] [Citation(s) in RCA: 274] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The RNA exosome complex is the most versatile RNA-degradation machine in eukaryotes. The exosome has a central role in several aspects of RNA biogenesis, including RNA maturation and surveillance. Moreover, it is emerging as an important player in regulating the expression levels of specific mRNAs in response to environmental cues and during cell differentiation and development. Although the mechanisms by which RNA is targeted to (or escapes from) the exosome are still not fully understood, general principles have begun to emerge, which we discuss in this Review. In addition, we introduce and discuss novel, previously unappreciated functions of the nuclear exosome, including in transcription regulation and in the maintenance of genome stability.
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10
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015. [PMID: 26579492 DOI: 10.3389/fonc.2015.00240] [] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination - a repair pathway activated in response to double-strand DNA breaks (DSB) - are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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11
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015. [PMID: 26579492 DOI: 10.3389/fonc.2015.00240]+[] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination - a repair pathway activated in response to double-strand DNA breaks (DSB) - are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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12
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Dungl DA, Maginn EN, Stronach EA. Preventing Damage Limitation: Targeting DNA-PKcs and DNA Double-Strand Break Repair Pathways for Ovarian Cancer Therapy. Front Oncol 2015; 5:240. [PMID: 26579492 PMCID: PMC4620694 DOI: 10.3389/fonc.2015.00240] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 10/10/2015] [Indexed: 12/22/2022] Open
Abstract
Platinum-based chemotherapy is the cornerstone of ovarian cancer treatment, and its efficacy is dependent on the generation of DNA damage, with subsequent induction of apoptosis. Inappropriate or aberrant activation of the DNA damage response network is associated with resistance to platinum, and defects in DNA repair pathways play critical roles in determining patient response to chemotherapy. In ovarian cancer, tumor cell defects in homologous recombination – a repair pathway activated in response to double-strand DNA breaks (DSB) – are most commonly associated with platinum-sensitive disease. However, despite initial sensitivity, the emergence of resistance is frequent. Here, we review strategies for directly interfering with DNA repair pathways, with particular focus on direct inhibition of non-homologous end joining (NHEJ), another DSB repair pathway. DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is a core component of NHEJ and it has shown considerable promise as a chemosensitization target in numerous cancer types, including ovarian cancer where it functions to promote platinum-induced survival signaling, via AKT activation. The development of pharmacological inhibitors of DNA-PKcs is on-going, and clinic-ready agents offer real hope to patients with chemoresistant disease.
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Affiliation(s)
- Daniela A Dungl
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Elaina N Maginn
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
| | - Euan A Stronach
- Molecular Therapy Laboratory, Department of Surgery and Cancer, Ovarian Cancer Action Research Centre, Imperial College London , London , UK
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13
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Wang JY, Chen SY, Sun CN, Chien T, Chern Y. A central role of TRAX in the ATM-mediated DNA repair. Oncogene 2015; 35:1657-70. [PMID: 26096928 DOI: 10.1038/onc.2015.228] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Revised: 05/04/2015] [Accepted: 05/18/2015] [Indexed: 12/21/2022]
Abstract
DNA repair is critical for the maintenance of genome stability. Upon genotoxic stress, dysregulated DNA repair may induce apoptosis. Translin-associated factor X (TRAX), which was initially identified as a binding partner of Translin, has been implicated in genome stability. However, the exact role of TRAX in DNA repair remains largely unknown. Here, we showed that TRAX participates in the ATM/H2AX-mediated DNA repair machinery by interacting with ATM and stabilizing the MRN complex at double-strand breaks. The exogenous expression of wild-type (WT) TRAX, but not a TRAX variant lacking the nuclear localization signal (NLS), rescued the vulnerability of TRAX-null mouse embryo fibroblasts (MEFs). This finding confirms the importance of the nuclear localization of TRAX in the repair of DNA damage. Compared with WT MEFs, TRAX-null MEFs exhibited impaired DNA repair (for example, reduced phosphorylation of ATM and H2AX) after treatment with ultra violet-C or γ-ray irradiation and a higher incidence of p53-mediated apoptosis. Our findings demonstrate that TRAX is required for MRN complex-ATM-H2AX signaling, which optimizes DNA repair by interacting with the activated ATM and protects cells from genotoxic stress-induced apoptosis.
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Affiliation(s)
- J-Y Wang
- Department of Neurology, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.,Neuroscience Division, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - S-Y Chen
- Neuroscience Division, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - C-N Sun
- Neuroscience Division, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - T Chien
- Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
| | - Y Chern
- Neuroscience Division, Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan.,Institute of Life Sciences, National Defense Medical Center, Taipei, Taiwan
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Abstract
SIGNIFICANCE Ionizing radiation (IR) is an effective and commonly employed treatment in the management of more than half of human malignancies. Because IR's ability to control tumors mainly relies on DNA damage, the cell's DNA damage response and repair (DRR) processes may hold the key to determining tumor responses. IR-induced DNA damage activates a number of DRR signaling cascades that control cell cycle arrest, DNA repair, and the cell's fate. DNA double-strand breaks (DSBs) generated by IR are the most lethal form of damage, and are mainly repaired via either homologous recombination (HR) or nonhomologous end-joining (NHEJ) pathways. RECENT ADVANCES In recent years, immense effort to understand and exploit the differences in the use of these repair pathways between tumors and normal cells will allow for an increase in tumor cell killing and a decrease in normal tissue injury. CRITICAL ISSUES Regulation of the two major DSB repair mechanisms (HR and NHEJ) and new strategies, which may improve the therapeutic ratio of radiation by differentially targeting HR and NHEJ function in tumor and normal tissues, is of intense interest currently, and is the focus of this article. FUTURE DIRECTIONS By utilizing the strategies outlined above, it may be possible to exploit differences between tumor and somatic cell DRR pathways, specifically their DSB repair mechanisms, to improve the therapeutic ratio of IR.
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Affiliation(s)
- Wil L Santivasi
- Department of Radiation Oncology, The Ohio State University College of Medicine , Columbus, Ohio
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15
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Sjakste N, Bielskiene K, Bagdoniene L, Labeikyte D, Gutcaits A, Vassetzky Y, Sjakste T. Tightly bound to DNA proteins: Possible universal substrates for intranuclear processes. Gene 2012; 492:54-64. [PMID: 22001404 DOI: 10.1016/j.gene.2011.09.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Revised: 09/08/2011] [Accepted: 09/22/2011] [Indexed: 01/05/2023]
Affiliation(s)
- N Sjakste
- Faculty of Medicine, University of Latvia, Šarlotes 1a, LV1001, Riga, Latvia
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16
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Lubas M, Chlebowski A, Dziembowski A, Jensen TH. Biochemistry and Function of RNA Exosomes. EUKARYOTIC RNASES AND THEIR PARTNERS IN RNA DEGRADATION AND BIOGENESIS, PART A 2012; 31:1-30. [DOI: 10.1016/b978-0-12-404740-2.00001-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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17
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Zhao BX, Chen HZ, Du XD, Luo J, He JP, Wang RH, Wang Y, Wu R, Hou RR, Hong M, Wu Q. Orphan receptor TR3 enhances p53 transactivation and represses DNA double-strand break repair in hepatoma cells under ionizing radiation. Mol Endocrinol 2011; 25:1337-50. [PMID: 21659476 DOI: 10.1210/me.2011-0081] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In response to ionizing radiation (IR)-induced DNA double-strand breaks (DSB), cells elicit an evolutionarily conserved checkpoint response that induces cell cycle arrest and either DNA repair or apoptosis, thereby maintaining genomic stability. DNA-dependent protein kinase (DNA-PK) is a central enzyme involved in DSB repair for mammalian cells that comprises a DNA-PK catalytic subunit and the Ku protein, which act as regulatory elements. DNA-PK also functions as a signaling molecule to selectively regulate p53-dependent apoptosis in response to IR. Herein, we demonstrate that the orphan nuclear receptor TR3 suppresses DSB repair by blocking Ku80 DNA-end binding activity and promoting DNA-PK-induced p53 activity in hepatoma cells. We find that TR3 interacts with Ku80 and inhibits its binding to DNA ends, which then suppresses DSB repair. Furthermore, TR3 is a phosphorylation substrate for DNA-PK and interacts with DNA-PK catalytic subunit in a Ku80-independent manner. Phosphorylated TR3, in turn, enhances DNA-PK-induced phosphorylation and p53 transcription activity, thereby enhancing IR-induced apoptosis in hepatoma cells. Together, our findings reveal novel functions for TR3, not only in DSB repair regulation but also in IR-induced hepatoma cell apoptosis, and they suggest that TR3 is a potential target for cancer radiotherapy.
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Affiliation(s)
- Bi-xing Zhao
- State Key Laboratory of Stress Cell Biology, School of Life Sciences, Xiamen University, Xiamen, Fujian Province, China
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18
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Mladenov E, Iliakis G. Induction and repair of DNA double strand breaks: the increasing spectrum of non-homologous end joining pathways. Mutat Res 2011; 711:61-72. [PMID: 21329706 DOI: 10.1016/j.mrfmmm.2011.02.005] [Citation(s) in RCA: 287] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2010] [Revised: 01/31/2011] [Accepted: 02/06/2011] [Indexed: 04/13/2023]
Abstract
A defining characteristic of damage induced in the DNA by ionizing radiation (IR) is its clustered character that leads to the formation of complex lesions challenging the cellular repair mechanisms. The most widely investigated such complex lesion is the DNA double strand break (DSB). DSBs undermine chromatin stability and challenge the repair machinery because an intact template strand is lacking to assist restoration of integrity and sequence in the DNA molecule. Therefore, cells have evolved a sophisticated machinery to detect DSBs and coordinate a response on the basis of inputs from various sources. A central function of cellular responses to DSBs is the coordination of DSB repair. Two conceptually different mechanisms can in principle remove DSBs from the genome of cells of higher eukaryotes. Homologous recombination repair (HRR) uses as template a homologous DNA molecule and is therefore error-free; it functions preferentially in the S and G2 phases. Non-homologous end joining (NHEJ), on the other hand, simply restores DNA integrity by joining the two ends, is error prone as sequence is only fortuitously preserved and active throughout the cell cycle. The basis of DSB repair pathway choice remains unknown, but cells of higher eukaryotes appear programmed to utilize preferentially NHEJ. Recent work suggests that when the canonical DNA-PK dependent pathway of NHEJ (D-NHEJ), becomes compromised an alternative NHEJ pathway and not HRR substitutes in a quasi-backup function (B-NHEJ). Here, we outline aspects of DSB induction by IR and review the mechanisms of their processing in cells of higher eukaryotes. We place particular emphasis on backup pathways of NHEJ and summarize their increasing significance in various cellular processes, as well as their potential contribution to carcinogenesis.
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Affiliation(s)
- Emil Mladenov
- Institute of Medical Radiation Biology, University of Duisburg-Essen Medical School, Hufelandstr. 55, 45122 Essen, Germany
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19
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Abstract
The Sas10/C1D domain is found in a small group of eukaryotic proteins that have functions in RNA processing events, translational control and DNA repair mechanisms. The domain is predicted to be alpha-helical in nature and comprises approx. 80 amino acid residues. Whereas the Sas10/C1D domain has yet to be functionally characterized, available results suggest that this domain forms a binding surface for specific interactions with other proteins and can concomitantly interact with RNA or DNA. This property of the Sas10/C1D domain may facilitate this family of proteins to dock other proteins on to nucleic acid substrates.
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20
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Ochi T, Sibanda BL, Wu Q, Chirgadze DY, Bolanos-Garcia VM, Blundell TL. Structural biology of DNA repair: spatial organisation of the multicomponent complexes of nonhomologous end joining. J Nucleic Acids 2010; 2010. [PMID: 20862368 PMCID: PMC2938450 DOI: 10.4061/2010/621695] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Accepted: 07/02/2010] [Indexed: 11/20/2022] Open
Abstract
Nonhomologous end joining (NHEJ) plays a major role in double-strand break DNA repair, which involves a series of steps mediated by multiprotein complexes. A ring-shaped Ku70/Ku80 heterodimer forms first at broken DNA ends, DNA-dependent protein kinase catalytic subunit (DNA-PKcs) binds to mediate synapsis and nucleases process DNA overhangs. DNA ligase IV (LigIV) is recruited as a complex with XRCC4 for ligation, with XLF/Cernunnos, playing a role in enhancing activity of LigIV. We describe how a combination of methods-X-ray crystallography, electron microscopy and small angle X-ray scattering-can give insights into the transient multicomponent complexes that mediate NHEJ. We first consider the organisation of DNA-PKcs/Ku70/Ku80/DNA complex (DNA-PK) and then discuss emerging evidence concerning LigIV/XRCC4/XLF/DNA and higher-order complexes. We conclude by discussing roles of multiprotein systems in maintaining high signal-to-noise and the value of structural studies in developing new therapies in oncology and elsewhere.
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Affiliation(s)
- Takashi Ochi
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1GA, UK
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21
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Malonia SK, Sinha S, Lakshminarasimhan P, Singh K, Jalota-Badhwar A, Rampalli S, Kaul-Ghanekar R, Chattopadhyay S. Gene regulation by SMAR1: Role in cellular homeostasis and cancer. Biochim Biophys Acta Rev Cancer 2010; 1815:1-12. [PMID: 20709157 DOI: 10.1016/j.bbcan.2010.08.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2010] [Revised: 08/04/2010] [Accepted: 08/06/2010] [Indexed: 12/22/2022]
Abstract
Changes in the composition of nuclear matrix associated proteins contribute to alterations in nuclear structure, one of the major phenotypes of malignant cancer cells. The malignancy-induced changes in this structure lead to alterations in chromatin folding, the fidelity of genome replication and gene expression programs. The nuclear matrix forms a scaffold upon which the chromatin is organized into periodic loop domains called matrix attachment regions (MAR) by binding to various MAR binding proteins (MARBPs). Aberrant expression of MARBPs modulates the chromatin organization and disrupt transcriptional network that leads to oncogenesis. Dysregulation of nuclear matrix associated MARBPs has been reported in different types of cancers. Some of these proteins have tumor specific expression and are therefore considered as promising diagnostic or prognostic markers in few cancers. SMAR1 (scaffold/matrix attachment region binding protein 1), is one such nuclear matrix associated protein whose expression is drastically reduced in higher grades of breast cancer. SMAR1 gene is located on human chromosome 16q24.3 locus, the loss of heterozygosity (LOH) of which has been reported in several types of cancers. This review elaborates on the multiple roles of nuclear matrix associated protein SMAR1 in regulating various cellular target genes involved in cell growth, apoptosis and tumorigenesis.
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22
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Li G, Liu J, Abu-Asab M, Masabumi S, Maru Y. XPB induces C1D expression to counteract UV-induced apoptosis. Mol Cancer Res 2010; 8:885-95. [PMID: 20530579 DOI: 10.1158/1541-7786.mcr-09-0467] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Although C1D has been shown to be involved in DNA double-strand break repair, how C1D expression was induced and the mechanism(s) by which C1D facilitates DNA repair in mammalian cells remain poorly understood. We and others have previously shown that expression of xeroderma pigmentosum B (XPB) protein efficiently compensated the UV irradiation-sensitive phenotype of 27-1 cells, which lack functional XPB. To further explore XPB-regulated genes that could be involved in UV-induced DNA repair, differential display analysis of mRNA levels from CHO-9, 27-1, and 27-1 complemented with wild-type XPB was done and C1D gene was identified as one of the major genes whose expression was significantly upregulated by restoring XPB function. We found that XPB is essential to induce C1D transcription after UV irradiation. The increase in C1D expression effectively compensates for the UV-induced proteolysis of C1D and thus maintains cellular C1D level to cope with DNA damage inflicted by UV irradiation. We further showed that although insufficient to rescue 27-1 cells from UV-induced apoptosis by itself, C1D facilitates XPB DNA repair through direct interaction with XPB. Our findings provided direct evidence that C1D is associated with DNA repair complex and may promote repair of UV-induced DNA damage.
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Affiliation(s)
- Guang Li
- Pediatric Tumor Biology and Ultrastructural Pathology Section, Laboratory of Pathology, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, MD 20892-1500, USA.
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23
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Griese JJ, Witte G, Hopfner KP. Structure and DNA binding activity of the mouse condensin hinge domain highlight common and diverse features of SMC proteins. Nucleic Acids Res 2010; 38:3454-65. [PMID: 20139420 PMCID: PMC2879519 DOI: 10.1093/nar/gkq038] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 01/14/2010] [Accepted: 01/14/2010] [Indexed: 01/13/2023] Open
Abstract
Structural Maintenance of Chromosomes (SMC) proteins are vital for a wide range of processes including chromosome structure and dynamics, gene regulation and DNA repair. Eukaryotes have three SMC complexes, consisting of heterodimeric pairs of six different SMC proteins along with several specific regulatory subunits. In addition to their other functions, all three SMC complexes play distinct roles in DNA repair. Cohesin (SMC1-SMC3) is involved in DNA double-strand break repair, condensin (SMC2-SMC4) participates in single-strand break (SSB) repair, and the SMC5-SMC6 complex functions in various DNA repair pathways. SMC proteins consist of N- and C-terminal domains that fold back onto each other to create an ATPase 'head' domain, connected to a central 'hinge' domain via long coiled-coils. The hinge domain mediates dimerization of SMC proteins and binds DNA, but it is not clear to what purpose this activity serves. We studied the structure and function of the condensin hinge domain from mouse. While the SMC hinge domain structure is largely conserved from prokaryotes to eukaryotes, its function seems to have diversified throughout the course of evolution. The condensin hinge domain preferentially binds single-stranded DNA. We propose that this activity plays a role in the SSB repair function of the condensin complex.
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Affiliation(s)
| | | | - Karl-Peter Hopfner
- Department of Biochemistry, Gene Center, Center for Integrated Protein Sciences and Munich Center for Advanced Photonics, Ludwig-Maximilians University Munich, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
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24
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Butler JS, Mitchell P. Rrp6, Rrp47 and Cofactors of the Nuclear Exosome. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 702:91-104. [DOI: 10.1007/978-1-4419-7841-7_8] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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25
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The pyridinylfuranopyrimidine inhibitor, PI-103, chemosensitizes glioblastoma cells for apoptosis by inhibiting DNA repair. Oncogene 2009; 28:3586-96. [PMID: 19633683 DOI: 10.1038/onc.2009.215] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The failure of conventional therapies in glioblastoma (GBM) is largely due to an aberrant activity of survival cascades, such as PI3 kinase (PI3K)/Akt-mediated signaling. This study is the first to show that the class I PI3K inhibitor, PI-103, enhances chemotherapy-induced cell death of GBM cells. Concurrent treatment with PI-103 and DNA-damaging drugs, in particular doxorubicin, significantly increases apoptosis and reduces colony formation compared with chemotherapy treatment alone. The underlying molecular mechanism for this chemosensitization was shown by two independent approaches, that is, pharmacological and genetic inhibition of PI3K, DNA-PK and mTOR, to involve inhibition of DNA-PK-mediated DNA repair. Accordingly, blockage of PI3K or DNA-PK, but not of mTOR, significantly delays the resolution of doxorubicin-induced DNA damage and concomitantly increases apoptosis. Importantly, not only are several GBM cell lines chemosensitized by PI-103 but also GBM stem cells. Clinical relevance was further confirmed by the use of primary cultured GBM cells, which also exhibit increased cell death and reduced colony formation on combined treatment with PI-103 and doxorubicin. By identifying class I PI3K inhibitors as powerful agents in enhancing the lethality of DNA-damaging drugs, to which GBMs are usually considered unresponsive, our findings have important implications for the design of rational combination regimens in overcoming the frequent chemoresistance of GBM.
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26
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Oyama S, Yamakawa H, Sasagawa N, Hosoi Y, Futai E, Ishiura S. Dysbindin-1, a schizophrenia-related protein, functionally interacts with the DNA- dependent protein kinase complex in an isoform-dependent manner. PLoS One 2009; 4:e4199. [PMID: 19142223 PMCID: PMC2614472 DOI: 10.1371/journal.pone.0004199] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 12/03/2008] [Indexed: 11/18/2022] Open
Abstract
DTNBP1 has been recognized as a schizophrenia susceptible gene, and its protein product, dysbindin-1, is down-regulated in the brains of schizophrenic patients. However, little is known about the physiological role of dysbindin-1 in the central nervous system. We hypothesized that disruption of dysbindin-1 with unidentified proteins could contribute to pathogenesis and the symptoms of schizophrenia. GST pull-down from human neuroblastoma lysates showed an association of dysbindin-1 with the DNA-dependent protein kinase (DNA-PK) complex. The DNA-PK complex interacts only with splice isoforms A and B, but not with C. We found that isoforms A and B localized in nucleus, where the kinase complex exist, whereas the isoform C was found exclusively in cytosol. Furthermore, results of phosphorylation assay suggest that the DNA-PK complex phosphorylated dysbindin-1 isoforms A and B in cells. These observations suggest that DNA-PK regulates the dysbindin-1 isoforms A and B by phosphorylation in nucleus. Isoform C does not contain exons from 1 to 6. Since schizophrenia-related single nucleotide polymorphisms (SNPs) occur in these introns between exon 1 and exon 6, we suggest that these SNPs might affect splicing of DTNBP1, which leads to impairment of the functional interaction between dysbindin-1 and DNA-PK in schizophrenic patients.
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Affiliation(s)
- Satoko Oyama
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Hidekuni Yamakawa
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Noboru Sasagawa
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Yoshio Hosoi
- Department of Radiological Technology, School of Health Sciences, Niigata University, Niigata-shi, Niigata, Japan
| | - Eugene Futai
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
| | - Shoichi Ishiura
- Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Meguro-ku, Tokyo, Japan
- * E-mail:
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27
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DNase I-resistant DNA-dependent protein kinase activity in Xenopus oocytes. Mol Cell Biochem 2007; 309:33-40. [DOI: 10.1007/s11010-007-9640-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Accepted: 10/18/2007] [Indexed: 10/22/2022]
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28
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Schilders G, van Dijk E, Pruijn GJ. C1D and hMtr4p associate with the human exosome subunit PM/Scl-100 and are involved in pre-rRNA processing. Nucleic Acids Res 2007; 35:2564-72. [PMID: 17412707 PMCID: PMC1885644 DOI: 10.1093/nar/gkm082] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The exosome is a complex of 3′–5′ exoribonucleases and RNA-binding proteins, which is involved in processing or degradation of different classes of RNA. Previously, the characterization of purified exosome complexes from yeast and human cells suggested that C1D and KIAA0052/hMtr4p are associated with the exosome and thus might regulate its functional activities. Subcellular localization experiments demonstrated that C1D and KIAA0052/hMtr4p co-localize with exosome subunit PM/Scl-100 in the nucleoli of HEp-2 cells. Additionally, the nucleolar accumulation of C1D appeared to be dependent on PM/Scl-100. Protein–protein interaction studies showed that C1D binds to PM/Scl-100, whereas KIAA0052/hMtr4p was found to interact with MPP6, a previously identified exosome-associated protein. Moreover, we demonstrate that C1D, MPP6 and PM/Scl-100 form a stable trimeric complex in vitro. Knock-down of C1D, MPP6 and KIAA0052/hMtr4p by RNAi resulted in the accumulation of 3′-extended 5.8S rRNA precursors, showing that these proteins are required for rRNA processing. Interestingly, C1D appeared to contain RNA-binding activity with a potential preference for structured RNAs. Taken together, our results are consistent with a role for the exosome-associated proteins C1D, MPP6 and KIAA052/hMtr4p in the recruitment of the exosome to pre-rRNA to mediate the 3′ end processing of the 5.8S rRNA.
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Affiliation(s)
| | | | - Ger J.M. Pruijn
- *To whom correspondence should be addressed +31 24 361 6847+31 24 354 0525
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29
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Rubin E, Wu X, Zhu T, Cheung JCY, Chen H, Lorincz A, Pandita RK, Sharma GG, Ha HC, Gasson J, Hanakahi LA, Pandita TK, Sukumar S. A role for the HOXB7 homeodomain protein in DNA repair. Cancer Res 2007; 67:1527-35. [PMID: 17308091 DOI: 10.1158/0008-5472.can-06-4283] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Homeobox genes encode transcription factors which function in body axis patterning in the developing embryo. Recent evidence suggests that the maintenance of specific HOX expression patterns is necessary for regulating the homeostasis of adult tissues as well. In this study, HOXB7 transformed human mammary epithelial cells, MCF10A, to grow in minimally supplemented medium, to form colonies in Matrigel, and display resistance to ionizing radiation. Searching for protein partners of HOXB7 that might contribute to resistance to ionizing radiation, we identified four HOXB7-binding proteins by GST pull-down/affinity chromatography and confirmed their interactions by coimmunoprecipitation in vivo. Interestingly, all four HOXB7-binding proteins shared functions as genomic caretakers and included members of the DNA-dependent protein kinase holoenzyme (Ku70, Ku80, DNA-PK(cs)) responsible for DNA double-strand break repair by nonhomologous end joining pathway and poly(ADP) ribose polymerase. Exogenous and endogenous expression of HOXB7 enhanced nonhomologous end joining and DNA repair functions in vitro and in vivo, which were reversed by silencing HOXB7. This is the first mechanistic study providing definitive evidence for the involvement of any HOX protein in DNA double-strand break repair.
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Affiliation(s)
- Ethel Rubin
- Department of Oncology, Johns Hopkins University School of Medicine, Baltimore, MD 21231, USA
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30
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Abstract
The exosome complex of 3'-->5' exonucleases is an important component of the RNA-processing machinery in eukaryotes. This complex functions in the accurate processing of nuclear RNA precursors and in the degradation of RNAs in both the nucleus and the cytoplasm. However, it has been unclear how different classes of substrate are distinguished from one another. Recent studies now provide insights into the regulation and structure of the exosome, and they reveal striking similarities between the process of RNA degradation in bacteria and eukaryotes.
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Affiliation(s)
- Jonathan Houseley
- Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, EH9 3JR, UK.
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31
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Dip R, Naegeli H. More than just strand breaks: the recognition of structural DNA discontinuities by DNA-dependent protein kinase catalytic subunit. FASEB J 2005; 19:704-15. [PMID: 15857885 DOI: 10.1096/fj.04-3041rev] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The DNA-dependent protein kinase (DNA-PK) is a trimeric factor originally identified as an enzyme that becomes activated upon incubation with DNA. Genetic defects in either the catalytic subunit (DNA-PK(CS)) or the two Ku components of DNA-PK result in immunodeficiency, radiosensitivity, and premature aging. This combined phenotype is generally attributed to the requirement for DNA-PK in the repair of DNA double strand breaks during various biological processes. However, recent studies revealed that DNA-PK(CS), a member of the growing family of phosphatidylinositol 3-kinases, participates in signal transduction cascades related to apoptotic cell death, telomere maintenance and other pathways of genome surveillance. These manifold functions of DNA-PK(CS) have been associated with an increasing number of protein interaction partners and phosphorylation targets. Here we review the DNA binding properties of DNA-PK(CS) and highlight its ability to interact with an astounding diversity of nucleic acid substrates. This survey indicates that the large catalytic subunit of DNA-PK functions as a sensor of not only broken DNA molecules, but of a wider spectrum of aberrant, unusual, or specialized structures that interrupt the standard double helical conformation of DNA.
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Affiliation(s)
- Ramiro Dip
- Institute of Veterinary Pharmacology and Toxicology, University of Zürich, Zürich, Switzerland
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32
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Abstract
DNA-PK is a protein complex that consists of a DNA-binding, regulatory subunit [Ku] and a larger approximately 465 kDa catalytic subunit [DNA-PKcs], a serine/threonine protein kinase. The kinase activity of DNA-PKcs resides between residues 3745 and 4013, a PI3 kinase domain. Another recognized domain within this large protein is a leucine zipper (LZ) motif or perhaps more appropriately designated a leucine rich region (LRR) that spans residues 1503-1602. Whereas, DNA-PK's kinase activity has been shown to be absolutely indispensable for its function in non-homologous end joining (NHEJ), little is known about the functional relevance of the LRR. Here we show that DNA-PKcs with point mutations in the LRR can only partially reverse the radiosensitive phenotype and V(D)J recombination deficits of DNA-PKcs deficient cells. Disruption of the LRR motif affects the ability to purify DNA-PKcs via its binding to DNA-cellulose, but does not affect its interaction with Ku or its catalytic activity. These data suggest that the LRR region of DNA-PKcs may contribute to its intrinsic DNA affinity, and moreover, that intrinsic DNA binding is important for optimal function of DNA-PKcs in repairing double strand breaks in living cells.
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Affiliation(s)
- Shikha Gupta
- Department of Microbiology and Molecular Genetics, College of Veterinary Medicine Michigan State UniversityEast Lansing, MI 48824, USA
| | - Katheryn Meek
- To whom correspondence should be addressed. Tel: +1 517 432 9505; Fax: +1 517 353 9004;
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33
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Abstract
DNA repair must take place within the context of chromatin, and it is therefore not surprising that many aspects of both chromatin components and proteins that modify chromatin have been implicated in this process. One of the best-characterized chromatin modification events in DNA-damage responses is the phosphorylation of the SQ motif found in histone H2A or the H2AX histone variant in higher eukaryotes. This modification is an early response to the induction of DNA damage, and occurs in a wide range of eukaryotic organisms, suggesting an important conserved function. One function that histone modifications can have is to provide a unique binding site for interacting factors. Here, we review the proteins and protein complexes that have been identified as H2AS129ph (budding yeast) or H2AXS139ph (human) binding partners and discuss the implications of these interactions.
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34
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Abstract
Double-strand breaks (DSBs) arise endogenously during normal cellular processes and exogenously by genotoxic agents such as ionizing radiation (IR). DSBs are one of the most severe types of DNA damage, which if left unrepaired are lethal to the cell. Several different DNA repair pathways combat DSBs, with nonhomologous end-joining (NHEJ) being one of the most important in mammalian cells. Competent NHEJ catalyses repair of DSBs by joining together and ligating two free DNA ends of little homology (microhomology) or DNA ends of no homology. The core components of mammalian NHEJ are the catalytic subunit of DNA protein kinase (DNA-PK(cs)), Ku subunits Ku70 and Ku80, Artemis, XRCC4 and DNA ligase IV. DNA-PK is a nuclear serine/threonine protein kinase that comprises a catalytic subunit (DNA-PK(cs)), with the Ku subunits acting as the regulatory element. It has been proposed that DNA-PK is a molecular sensor for DNA damage that enhances the signal via phosphorylation of many downstream targets. The crucial role of DNA-PK in the repair of DSBs is highlighted by the hypersensitivity of DNA-PK(-/-) mice to IR and the high levels of unrepaired DSBs after genotoxic insult. Recently, DNA-PK has emerged as a suitable genetic target for molecular therapeutics such as siRNA, antisense and novel inhibitory small molecules. This review encompasses the recent literature regarding the role of DNA-PK in the protection of genomic stability and focuses on how this knowledge has aided the development of specific DNA-PK inhibitors, via both small molecule and directed molecular targeting techniques. This review promotes the inhibition of DNA-PK as a valid approach to enhance the tumor-cell-killing effects of treatments such as IR.
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Affiliation(s)
- Spencer J Collis
- Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD 21231, USA.
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35
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Abstract
Efficient repair of DNA double-strand breaks is essential for the maintenance of chromosomal integrity. In higher eukaryotes, non-homologous end-joining (NHEJ) DNA is the primary pathway that repairs these breaks. NHEJ also functions in developing lymphocytes to repair strand breaks that occur during V(D)J recombination, the site-specific recombination process that provides for the assembly of functional antigen-receptor genes. If V(D)J recombination is impaired, B- and T-lymphocyte development is blocked resulting in severe combined immunodeficiency disease. In the last decade, an intensive research effort has focused on NHEJ resulting in a reasonable understanding of how double-strand breaks are resolved. Six distinct gene products have been identified that function in this pathway (Ku70, Ku86, XRCC4, DNA ligase IV, Artemis, and DNA-PKcs). Three of these comprise one complex, the DNA-dependent protein kinase (DNA-PK). This protein complex is central during NHEJ, because DNA-PK initially recognizes and binds to the damaged DNA and then targets the other repair activities to the site of DNA damage. In this review, we discuss recent developments that have provided insight into how DNA-PK functions, once bound to DNA ends.
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Affiliation(s)
- Katheryn Meek
- College of Veterinary Medicine and Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, MI 48824, USA
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36
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Dip R, Naegeli H. Binding of the DNA-dependent protein kinase catalytic subunit to Holliday junctions. Biochem J 2004; 381:165-74. [PMID: 15035658 PMCID: PMC1133774 DOI: 10.1042/bj20031666] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2003] [Revised: 03/03/2004] [Accepted: 03/22/2004] [Indexed: 11/17/2022]
Abstract
DNA-PK (DNA-dependent protein kinase) is a double-strand break sensor involved in DNA repair and signal transduction. In the present study, we constructed site-directed cross-linking probes to explore the range of DNA discontinuities that are recognized by DNA-PK(CS) (DNA-PK catalytic subunit). A comparison between different substrate architectures showed that DNA-PK(CS) associates preferentially with the crossover region of synthetic Holliday junctions. This interaction with four-way junctions was preserved when biotin-streptavidin complexes were assembled at the termini to exclude the binding of Ku proteins. The association of DNA-PK(CS) with Holliday junctions was salt-labile even in the presence of Ku proteins, but this interaction could be stabilized when the DNA probes were incubated with the endogenous enzyme in nuclear extracts of human cells. Cross-linking of the endogenous enzyme in cellular extracts also demonstrated that DNA-PK(CS) binds to DNA ends and four-way junctions with similar affinities in the context of a nuclear protein environment. Kinase assays using p53 proteins as a substrate showed that, in association with four-way structures, DNA-PK(CS) adopts an active conformation different from that in the complex with linear DNA. Our results are consistent with a structure-specific, but Ku- and DNA end-independent, recruitment of DNA-PK(CS) to Holliday junction intermediates. This observation suggests an unexpected functional link between the two main pathways that are responsible for the repair of DNA double-strand breaks in mammalian cells.
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Affiliation(s)
- Ramiro Dip
- Institute of Pharmacology and Toxicology, University of Zürich-Tierspital, Winterthurerstrasse 260, 8057 Zürich, Switzerland
| | - Hanspeter Naegeli
- Institute of Pharmacology and Toxicology, University of Zürich-Tierspital, Winterthurerstrasse 260, 8057 Zürich, Switzerland
- To whom correspondence should be addressed (e-mail )
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Feng J, Park J, Cron P, Hess D, Hemmings BA. Identification of a PKB/Akt hydrophobic motif Ser-473 kinase as DNA-dependent protein kinase. J Biol Chem 2004; 279:41189-96. [PMID: 15262962 DOI: 10.1074/jbc.m406731200] [Citation(s) in RCA: 386] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Full activation of protein kinase B (PKB)/Akt requires phosphorylation on Thr-308 and Ser-473 by 3-phosphoinositide-dependent kinase-1 (PDK1) and Ser-473 kinase (S473K), respectively. Although PDK1 has been well characterized, the identification of the S473K remains controversial. A major PKB Ser-473 kinase activity was purified from the membrane fraction of HEK293 cells and found to be DNA-dependent protein kinase (DNA-PK). DNA-PK co-localized and associated with PKB at the plasma membrane. In vitro, DNA-PK phosphorylated PKB on Ser-473, resulting in a approximately 10-fold enhancement of PKB activity. Knockdown of DNA-PK by small interfering RNA inhibited Ser-473 phosphorylation induced by insulin and pervanadate. DNA-PK-deficient glioblastoma cells did not respond to insulin at the level of Ser-473 phosphorylation; this effect was restored by complementation with the human PRKDC gene. We conclude that DNA-PK is a long sought after kinase responsible for the Ser-473 phosphorylation step in the activation of PKB.
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Affiliation(s)
- Jianhua Feng
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, Basel CH-4058, Switzerland
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38
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Wang YG, Nnakwe C, Lane WS, Modesti M, Frank KM. Phosphorylation and regulation of DNA ligase IV stability by DNA-dependent protein kinase. J Biol Chem 2004; 279:37282-90. [PMID: 15194694 DOI: 10.1074/jbc.m401217200] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA ligase IV (Lig4), x-ray cross-complementation group 4 (XRCC4), and DNA-dependent protein kinase (DNA-PK) are essential mammalian nonhomologous end joining proteins used for V(D)J recombination and DNA repair. Previously a Lig4 peptide was reported to be an in vitro substrate for DNA-PK, but the phosphorylation state of Lig4 protein in vivo is not known. In this study, we report that a full-length Lig4 construct was expressed as a phosphoprotein in the cell. Also the full-length Lig4 protein, in complex with XRCC4, was an in vitro substrate for DNA-PK. Using tandem mass spectrometry, we identified a DNA-PK phosphorylation site at Thr-650 in human Lig4 and a potential second phosphorylation site at Ser-668 or Ser-672. Phosphorylation of Lig4 per se was not required for Lig4 DNA end joining activity. Substitution of these amino acids with alanine, individually or in combination, led to changes in Lig4 protein stability of mouse Lig4. The phosphomimetic mutation S650D returned Lig4 stability to that of the wild-type protein. Furthermore DNA-PK was found to negatively regulate Lig4 protein stability. Our results suggest that Lig4 stability is regulated by multiple factors, including interaction with XRCC4, phosphorylation status, and possibly Lig4 conformation.
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Affiliation(s)
- Yu-Gang Wang
- Department of Pathology, University of Chicago, Chicago, Illinois 60637, USA
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Askree SH, Yehuda T, Smolikov S, Gurevich R, Hawk J, Coker C, Krauskopf A, Kupiec M, McEachern MJ. A genome-wide screen for Saccharomyces cerevisiae deletion mutants that affect telomere length. Proc Natl Acad Sci U S A 2004; 101:8658-63. [PMID: 15161972 PMCID: PMC423251 DOI: 10.1073/pnas.0401263101] [Citation(s) in RCA: 283] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Telomeres are nucleoprotein structures present at the ends of eukaryotic chromosomes that play a central role in guarding the integrity of the genome by protecting chromosome ends from degradation and fusion. Length regulation is central to telomere function. To broaden our knowledge about the mechanisms that control telomere length, we have carried out a systematic examination of approximately 4,800 haploid deletion mutants of Saccharomyces cerevisiae for telomere-length alterations. By using this screen, we have identified >150 candidate genes not previously known to affect telomere length. In two-thirds of the identified mutants, short telomeres were observed; whereas in one-third, telomeres were lengthened. The genes identified are very diverse in their functions, but certain categories, including DNA and RNA metabolism, chromatin modification, and vacuolar traffic, are overrepresented. Our results greatly enlarge the number of known genes that affect telomere metabolism and will provide insights into how telomere function is linked to many other cellular processes.
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Affiliation(s)
- Syed H Askree
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
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40
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Chen ES, Sutani T, Yanagida M. Cti1/C1D interacts with condensin SMC hinge and supports the DNA repair function of condensin. Proc Natl Acad Sci U S A 2004; 101:8078-83. [PMID: 15148393 PMCID: PMC419560 DOI: 10.1073/pnas.0307976101] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Condensin is a conserved five-subunit complex containing two SMC (structural maintenance of chromosomes) and three non-SMC subunits and plays a major role in mitotic chromosome condensation. Condensin also acts in interphase and is required for DNA repair and replication checkpoint control. We attempted to study the function of the condensin in greater detail by means of the isolation of interacting proteins with the two-hybrid system. Using the hinge domain of Cut3/SMC4 as bait, we found one Cut three-interacting (Cti) 14-kDa nuclear protein, Cti1. GST pull-down assay and immunoprecipitation supported physical interaction between Cti1 and condensin. Cti1 is similar to human C1D, which associates tightly with genomic DNA and functions to activate DNA protein kinase. SpC1D is essential for viability. The null mutant could germinate but arrest after replication, indicating that it is required for interphase growth. Importantly, an elevated dosage of spC1D suppressed the temperature, UV irradiation, and hydroxyurea sensitivity of the mutant of Cnd2, a non-SMC subunit of condensin. Upon exposure to hydroxyurea, spC1D accumulated on the nuclear chromatin, and the fraction of spC1D that was chromatin-bound increased. Cti1 is the first example of the protein that interacts with the hinge domain of SMC. Cti1 may have a supporting role for the DNA repair function of condensin.
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Affiliation(s)
- Ee Sin Chen
- Department of Gene Mechanisms, Graduate School of Biostudies, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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41
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Affiliation(s)
- Jessica A Downs
- Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA, UK.
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Dittmann K, Virsik-Köpp P, Mayer C, Rave-Fränk M, Rodemann HP. Bowman-Birk protease inhibitor activates DNA-dependent protein kinase and reduces formation of radiation-induced dicentric chromosomes. Int J Radiat Biol 2004; 79:801-8. [PMID: 14630539 DOI: 10.1080/09553000310001610277] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
PURPOSE To test a stimulatory effect of the radioprotector Bowman Birk protease inhibitor (BBI) upon DNA repair processes. MATERIALS AND METHODS An effect of BBI upon DNA repair was investigated by quantification of radiation-induced dicentric chromosomes. Sensitivity to ionizing radiation was determined by clonogenic survival assay. Quantification of activity of the DNA-dependent kinase was performed by immunoprecipitation and phosphorylation of a TP53-derived peptide. RESULTS The formation of radiation-induced dicentric chromosomes was reduced significantly after pretreatment of cells with BBI. By using a cell line with an inducible expression of a mutated TP53, it was shown that the BBI-mediated reduction of dicentric chromosome formation depended on the presence of wild-type TP53. To get further insights into the molecular mode of action of BBI, activity of the DNA-dependent protein kinase (DNA-PK) was quantified. BBI treatment resulted in a stimulation of basal (DNA-PK) activity. In SCID mouse fibroblasts deficient in DNA-PK activity, BBI failed to reduce the amount of radiation-induced dicentric chromosomes and the radioprotective effect was absent. Likewise, cells expressing mt.TP53 did not show radioprotection by BBI. CONCLUSIONS It was observed that BBI exerts its radioprotective effect by a reduction of incorrect DNA repair, resulting in a reduced amount of dicentric chromosomes. This effect on the fidelity of DNA repair is TP53 dependent and correlated with induction of DNA-PK activity.
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Affiliation(s)
- K Dittmann
- Section of Radiobiology and Environmental Research, Department of Radiation Oncology University of Tübingen Röntgenweg 11 D-72076 Tübingen Germany
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Mitchell P, Petfalski E, Houalla R, Podtelejnikov A, Mann M, Tollervey D. Rrp47p is an exosome-associated protein required for the 3' processing of stable RNAs. Mol Cell Biol 2003; 23:6982-92. [PMID: 12972615 PMCID: PMC193929 DOI: 10.1128/mcb.23.19.6982-6992.2003] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2003] [Revised: 05/23/2003] [Accepted: 07/03/2003] [Indexed: 11/20/2022] Open
Abstract
Related exosome complexes of 3'-->5' exonucleases are present in the nucleus and the cytoplasm. Purification of exosome complexes from whole-cell lysates identified a Mg(2+)-labile factor present in substoichiometric amounts. This protein was identified as the nuclear protein Yhr081p, the homologue of human C1D, which we have designated Rrp47p (for rRNA processing). Immunoprecipitation of epitope-tagged Rrp47p confirmed its interaction with the exosome and revealed its association with Rrp6p, a 3'-->5' exonuclease specific to the nuclear exosome fraction. Northern analyses demonstrated that Rrp47p is required for the exosome-dependent processing of rRNA and small nucleolar RNA (snoRNA) precursors. Rrp47p also participates in the 3' processing of U4 and U5 small nuclear RNAs (snRNAs). The defects in the processing of stable RNAs seen in rrp47-Delta strains closely resemble those of strains lacking Rrp6p. In contrast, Rrp47p is not required for the Rrp6p-dependent degradation of 3'-extended nuclear pre-mRNAs or the cytoplasmic 3'-->5' mRNA decay pathway. We propose that Rrp47p functions as a substrate-specific nuclear cofactor for exosome activity in the processing of stable RNAs.
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Affiliation(s)
- Philip Mitchell
- Wellcome Trust Centre for Cell Biology, Institute for Cell and Molecular Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.
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44
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Chen S, Paul P, Price BD. ATM's leucine-rich domain and adjacent sequences are essential for ATM to regulate the DNA damage response. Oncogene 2003; 22:6332-9. [PMID: 14508513 DOI: 10.1038/sj.onc.1206760] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ATM protein kinase regulates the DNA damage response by phosphorylating proteins involved in cell cycle checkpoints and DNA repair. We report here on the function of the predicted leucine zipper (LZ) motif, and sequences adjacent to this, in regulating ATM activity. The predicted LZ sequence was deleted from ATM, generating ATMDeltaLZ, and expressed in an ATM-negative AT cell line. ATM increased cell survival following exposure to ionizing radiation, whereas expression of ATMDeltaLZ failed to increase cell survival. ATMDeltaLZ retained in vitro kinase activity, but was unable to phosphorylate p53 in vivo. Leucine zippers mediate homo- and heterodimerization of proteins. However, the predicted LZ of ATM did not mediate the formation of ATM dimers. We examined if the predicted LZ of ATM was a dominant-negative inhibitor of ATM function in SW480 cells. Expression of amino acids 769-1436 of ATM, including the predicted LZ, sensitized SW480 cells to ionizing radiation, but did not inhibit ATM's kinase activity or its ability to phosphorylate Brca1. Further, this dominant-negative activity was not dependent on the predicted LZ domain. The central region of the ATM protein therefore contains multiple sequences which regulate cell survival following DNA damage.
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Affiliation(s)
- Shujuan Chen
- Department of Radiation Oncology, JF513, Dana-Farber Cancer Institute, Harvard Medical School, 44 Binney Street, Boston, MA 02115, USA
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45
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Lucero H, Gae D, Taccioli GE. Novel localization of the DNA-PK complex in lipid rafts: a putative role in the signal transduction pathway of the ionizing radiation response. J Biol Chem 2003; 278:22136-43. [PMID: 12672807 DOI: 10.1074/jbc.m301579200] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increased sensitivity to ionizing radiation (IR) has been shown to be due to defects in DNA double-strand break repair machinery. The major pathway in mammalian cells dedicated to the repair of DNA double-strand breaks is by the nonhomologous end-joining machinery. Six components function in this pathway, of which three (Ku70, Ku86, and DNA-PKcs) constitute a protein complex known as DNA-dependent protein kinase (DNA-PK). However, it is now recognized that the cellular radiation response is complex, and radiosensitivity may be also regulated at different levels in the radiation signal transduction pathway. In addition to DNA damage, exposure to IR triggers intracellular signaling cascades that overlap with pathways initiated by ligand engagement to a receptor. In this study, we provide evidence for the novel localization of the DNA-PK complex in lipid rafts. We also show this property is not a generalized characteristic of all DNA repair proteins. Furthermore, we have detected Ku86 in yeast lipid rafts. Our results suggest that the components of this complex might be recruited separately to the plasma membrane by tethering with raft-resident proteins. In addition, we found an irradiation-induced differential protein phosphorylation pattern dependent upon DNA-PKcs in lipid rafts. Thus, we speculate that another role for the DNA-PKcs subunit and perhaps for the holoenzyme is in the signal transduction of IR response.
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Affiliation(s)
- Hector Lucero
- Departments of Molecular and Cellular Biology, Goldman School of Dental Medicine, Boston University, Boston, MA 02118, USA
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46
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Ko L, Chin WW. Nuclear receptor coactivator thyroid hormone receptor-binding protein (TRBP) interacts with and stimulates its associated DNA-dependent protein kinase. J Biol Chem 2003; 278:11471-9. [PMID: 12519782 DOI: 10.1074/jbc.m209723200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nuclear receptors mediate gene activation through ligand-dependent interaction with coactivators. We previously cloned and characterized thyroid hormone receptor-binding protein, TRBP (NcoA6: AIB3/ASC-2/RAP250/PRIP/TRBP/NRC), as an LXXLL-containing coactivator that associates with coactivator complexes through its C terminus. To search for protein factors involved in TRBP action, we identified a distinct set of proteins from HeLa nuclear extract that interacts with the C terminus of TRBP. Analysis by mass spectrometric protein sequencing revealed a DNA-dependent protein kinase (DNA-PK) complex including its catalytic subunit and regulatory subunits, Ku70 and Ku86. DNA-PK is a heterotrimeric nuclear phosphatidylinositol 3-kinase that functions in DNA repair, recombination, and transcriptional regulation. DNA-PK phosphorylates TRBP at its C-terminal region, which directly interacts with Ku70 but not Ku86 in vitro. In addition, in the absence of DNA, TRBP itself activates DNA-PK, and the TRBP-stimulated DNA-PK activity has an altered phosphorylation pattern from DNA-stimulated activity. An anti-TRBP antibody inhibits TRBP-induced kinase activity, suggesting that protein content of TRBP is responsible for the stimulation of DNA-independent kinase activity. Furthermore, in DNA-PK-deficient scid cells, TRBP-mediated transactivation is significantly impaired, and nuclear localization of TRBP is altered. The activation of DNA-PK in the absence of DNA ends by the coactivator TRBP suggests a novel mechanism of coactivator-stimulated DNA-PK phosphorylation in transcriptional regulation.
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Affiliation(s)
- Lan Ko
- Department of Gene Regulation, Bone and Inflammation Research, Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA.
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47
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Yang J, Yu Y, Duerksen-Hughes PJ. Protein kinases and their involvement in the cellular responses to genotoxic stress. Mutat Res 2003; 543:31-58. [PMID: 12510016 DOI: 10.1016/s1383-5742(02)00069-8] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Cells are constantly subjected to genotoxic stress, and much has been learned regarding their response to this type of stress during the past year. In general, the cellular genotoxic response can be thought to occur in three stages: (1) damage sensing; (2) activation of signal transduction pathways; (3) biological consequences and attenuation of the response. The biological consequences, in particular, include cell cycle arrest and cell death. Although our understanding of the molecular mechanisms underlying cellular genotoxic stress responses remains incomplete, many cellular components have been identified over the years, including a group of protein kinases that appears to play a major role. Various DNA-damaging agents can activate these protein kinases, triggering a protein phosphorylation cascade that leads to the activation of transcription factors, and altering gene expression. In this review, the involvement of protein kinases, particularly the mitogen-activated protein kinases (MAPKs), at different stages of the genotoxic response is discussed.
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Affiliation(s)
- Jun Yang
- Department of Pathophysiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310031, China
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48
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Ai R, Sandoval A, Labhart P. Differential gene expression in human glioma cells: correlation with presence or absence of DNA-dependent protein kinase. Gene Expr 2003; 11:35-45. [PMID: 12691524 PMCID: PMC5991153 DOI: 10.3727/000000003783992306] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/16/2002] [Indexed: 11/24/2022]
Abstract
The human glioma cell line M059J is deficient in DNA-dependent protein kinase (DNA-PK) due to a frame-shift mutation in PRKDC, the gene for its catalytic subunit, while cell line M059K, isolated from the same malignant tumor, has normal DNA-PK activity. DNA-PK is required for double-strand DNA break repair, and its absence is responsible for increased radiosensitivity of M059J. We show that transcripts of several melanoma antigen subfamily A (MAGE-A) genes, the expression of which is restricted to tumor and germ-line cells,are present in M059K, but that their expression is strongly downregulated in M059J. Normal levels of MAGE-A expression are restored in the PRKDC-complemented cell line M059J/Fus1, suggesting that the presence of DNA-PK is required for MAGE-A gene transcription. We also show that the MAGE-A1 promoter is methylated in M059J, while the promoter is demethylated in M059K and M059J/Fus1. Other genes, including all three major histocompatibility class I (HLA) genes, BENE, and an unnamed gene related to CNIL(CORNICHON-like), display an opposite expression profile (i.e., they are upregulated in the DNA-PK-deficient cell line, but show low levels of expression in both M059K and in the PRKDC-complemented cell line). For these genes, differential expression does not correlate with DNA methylation in upstream promoter sequences. Our results suggest that the presence of DNA-PK can exert effects on gene expression by various mechanisms and pathways, thus affecting overall cell physiology even in the absence of DNA damage.
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Affiliation(s)
- Rong Ai
- Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121
| | - Ana Sandoval
- Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121
| | - Paul Labhart
- Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121
- Address correspondence to Paul Labhart, Torrey Pines Institute for Molecular Studies, 3550 General Atomics Court, San Diego, CA 92121. Tel: (858) 455-3857; Fax: (858) 455-3804; E-mail:
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Erdemir T, Bilican B, Cagatay T, Goding CR, Yavuzer U. Saccharomyces cerevisiae C1D is implicated in both non-homologous DNA end joining and homologous recombination. Mol Microbiol 2002; 46:947-57. [PMID: 12421302 DOI: 10.1046/j.1365-2958.2002.03224.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
C1D is a gamma-irradiation inducible nuclear matrix protein that interacts with and activates the DNA-dependent protein kinase (DNA-PK) that is essential for the repair of the DNA double-strand breaks and V(D)J recombination. Recently, it was demonstrated that C1D can also interact with TRAX and prevent the association of TRAX with Translin, a factor known to bind DNA break-point junctions, and that over expression of C1D can induce p53-dependent apoptosis. Taken together, these findings suggest that mammalian C1D could be involved in maintenance of genome integrity by regulating the activity of proteins involved in DNA repair and recombination. To obtain direct evidence for the biological function of C1D that we show is highly conserved between diverse species, we have analysed the Saccharomyces cerevisiae C1D homologue. We report that the disruption of the YC1D gene results in a temperature sensitivity and that yc1d mutant strains exhibit defects in non-homologous DNA end joining (NHEJ) and accurate DNA repair. In addition, using a novel plasmid-based in vivo recombination assay, we show that yc1d mutant strains are also defective in homologous recombination. These results indicate that YC1D is implicated in both homologous recombination and NHEJ pathways for the repair of DNA double-strand breaks.
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Affiliation(s)
- Tuba Erdemir
- Bikent University, Molecular Biology and Genetics Department, Ankara, Turkey
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50
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Mauldin SK, Getts RC, Liu W, Stamato TD. DNA-PK-dependent binding of DNA ends to plasmids containing nuclear matrix attachment region DNA sequences: evidence for assembly of a repair complex. Nucleic Acids Res 2002; 30:4075-87. [PMID: 12235392 PMCID: PMC137113 DOI: 10.1093/nar/gkf529] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
We find that nuclear protein extracts from mammalian cells contain an activity that allows DNA ends to associate with circular pUC18 plasmid DNA. This activity requires the catalytic subunit of DNA-PK (DNA-PKcs) and Ku since it was not observed in mutants lacking Ku or DNA-PKcs but was observed when purified Ku/DNA-PKcs was added to these mutant extracts. Purified Ku/DNA-PKcs alone did not produce association of DNA ends with plasmid DNA suggesting that additional factors in the nuclear extract are necessary for this activity. Competition experiments between pUC18 and pUC18 plasmids containing various nuclear matrix attachment region (MAR) sequences suggest that DNA ends preferentially associate with plasmids containing MAR DNA sequences. At a 1:5 mass ratio of MAR to pUC18, approximately equal amounts of DNA end binding to the two plasmids were observed, while at a 1:1 ratio no pUC18 end binding was observed. Calculation of relative binding activities indicates that DNA end-binding activities to MAR sequences was 7-21-fold higher than pUC18. Western analysis of proteins bound to pUC18 and MAR plasmids indicates that XRCC4, DNA ligase IV and scaffold attachment factor A preferentially associate with the MAR plasmid in the absence or presence of DNA ends. In contrast, Ku and DNA-PKcs were found on the MAR plasmid only in the presence of DNA ends suggesting that binding of these proteins to DNA ends is necessary for their association with MAR DNA. The ability of DNA-PKcs/Ku to direct DNA ends to MAR and pUC18 plasmid DNA is a new activity for DNA-PK and may be important for its function in double-strand break repair. A model for DNA repair based on these observations is presented.
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Affiliation(s)
- Stanley K Mauldin
- Lankenau Institute for Medical Research, 100 Lancaster Avenue, Wynnewood, PA 19096, USA and Genisphere, Incorporated, 4170 City Avenue, Philadelphia, PA 19131-1694, USA
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