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Yamaguchi T, Masago K, Sasaki E, Kuroda H, Matsushita H, Horio Y. EML4-ALK Variant 3a/b as a mechanism of osimertinib resistance in a patient with EGFR L858R positive NSCLC. Cancer Genet 2024; 280-281:13-16. [PMID: 38128381 DOI: 10.1016/j.cancergen.2023.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/08/2023] [Accepted: 12/07/2023] [Indexed: 12/23/2023]
Affiliation(s)
- Teppei Yamaguchi
- Department of Thoracic Oncology, Aichi Cancer Center Hospital, Japan
| | - Katsuhiro Masago
- Department of Pathology and Molecular Diagnostics, Aichi Cancer Center Hospital, Japan; Division of Translational Oncoimmunology, Aichi Cancer Research Institute, Nagoya, Japan.
| | - Eiichi Sasaki
- Department of Pathology and Molecular Diagnostics, Aichi Cancer Center Hospital, Japan
| | - Hiroaki Kuroda
- Department of Respiratory Surgery, Aichi Cancer Center Hospital, Nagoya, Japan; Department of Thoracic Surgery, Teikyo University Mizonokuchi Hospital, Tokyo, Japan; Division of Translational Oncoimmunology, Aichi Cancer Research Institute, Nagoya, Japan
| | - Hirokazu Matsushita
- Division of Translational Oncoimmunology, Aichi Cancer Research Institute, Nagoya, Japan
| | - Yoshitsugu Horio
- Department of Thoracic Oncology, Aichi Cancer Center Hospital, Japan; Division of Translational Oncoimmunology, Aichi Cancer Research Institute, Nagoya, Japan
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2
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Transcriptome analysis of HEK 293T cells revealed different significance of the depletion of DNA-dependent protein kinase subunits, Ku70, Ku80, and DNA-PKcs. Biochimie 2022; 199:139-149. [DOI: 10.1016/j.biochi.2022.04.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/17/2022] [Accepted: 04/12/2022] [Indexed: 01/08/2023]
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3
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Xing M, Bjørås M, Daniel JA, Alt FW, Oksenych V. Synthetic lethality between murine DNA repair factors XLF and DNA-PKcs is rescued by inactivation of Ku70. DNA Repair (Amst) 2017; 57:133-138. [PMID: 28759779 PMCID: PMC5584571 DOI: 10.1016/j.dnarep.2017.07.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/25/2017] [Accepted: 07/24/2017] [Indexed: 11/18/2022]
Abstract
DNA double-strand breaks (DSBs) are recognized and repaired by the Classical Non-Homologous End-Joining (C-NHEJ) and Homologous Recombination pathways. C-NHEJ includes the core Ku70 and Ku80 (or Ku86) heterodimer that binds DSBs and thus promotes recruitment of accessory downstream NHEJ factors XLF, PAXX, DNA-PKcs, Artemis and other core subunits, XRCC4 and DNA Ligase 4 (Lig4). In the absence of core C-NHEJ factors, DNA repair can be performed by Alternative End-Joining, which likely depends on DNA Ligase 1 and DNA Ligase 3. Genetic inactivation of C-NHEJ factors, such as Ku70, Ku80, XLF, PAXX and DNA-PKcs results in viable mice showing increased levels of genomic instability and sensitivity to DSBs. Knockouts of XRCC4 or Lig4, on the other hand, as well as combined inactivation of XLF and DNA-PKcs, or XLF and PAXX, result in late embryonic lethality in mice, which in most cases correlate with severe apoptosis in the central nervous system. Here, we demonstrate that inactivation of the Ku70 gene rescues the synthetic lethality between XLF and DNA-PKcs, resulting in triple knockout mice that are indistinguishable from Ku70-deficient littermates by size or levels of genomic instability. Moreover, we find that combined inactivation of Ku70 and XLF results in viable mice. Together, these findings suggest that Ku70 is epistatic with XLF and DNA-PKcs and support a model in which inactivation of Ku70 allows DNA lesions to become accessible to alternative DNA repair pathways.
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Affiliation(s)
- Mengtan Xing
- Institute for Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons Gate 1, 7491 Trondheim, Norway
| | - Magnar Bjørås
- Institute for Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons Gate 1, 7491 Trondheim, Norway
| | - Jeremy A Daniel
- The NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Frederick W Alt
- Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States.
| | - Valentyn Oksenych
- Institute for Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, Laboratory Center, Erling Skjalgssons Gate 1, 7491 Trondheim, Norway; The NNF Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark; Howard Hughes Medical Institute, Program in Cellular and Molecular Medicine, Boston Children's Hospital, Department of Genetics, Harvard Medical School, Boston, MA 02115, United States; St. Olavs Hospital, Trondheim University Hospital, Clinic of Medicine, Postboks 3250 Sluppen, 7006 Trondheim, Norway.
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4
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Characterization of HIV-1 integrase interaction with human Ku70 protein and initial implications for drug targeting. Sci Rep 2017; 7:5649. [PMID: 28717247 PMCID: PMC5514147 DOI: 10.1038/s41598-017-05659-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 06/01/2017] [Indexed: 11/27/2022] Open
Abstract
Human Ku70/Ku80 protein is known to influence HIV-1 replication. One of the possible reasons may be the protection of integrase from proteasomal degradation by Ku70 subunit. We demonstrated that recombinant HIV-1 integrase and Ku70 form a stable complex, while no interaction of Ku70 with integrase from prototype foamy virus was observed. By analyzing protein subdomains we determined two binding sites in the structure of both Ku70 and integrase: the 51–160 a.a. region of integrase interacts with residues 251–438 of Ku70, whereas Ku70 N-terminal domain (1–250 a.a.) contacts an α6-helix in the 200–220 a.a. integrase region. Single substitutions within integrase (E212A or L213A) block the interaction with Ku70 thus indicating that the binding site formed by the 200–220 a.a. integrase region is crucial for complex formation. E212A/L213A substitutions decreased the integrase capacity to bind Ku70 in HEK293T cells. A conjugate of 2′-ОMe-GGUUUUUGUGU oligonucleotide with eosin is shown by molecular modeling to shield integrase residues E212/L213 and is effective in blocking complex formation of Ku70 with integrase what makes the complex between α6-helix and Ku70(1–250) a possible target for drug development.
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5
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Ngo J, Matsuyama M, Kim C, Poventud-Fuentes I, Bates A, Siedlak SL, Lee HG, Doughman YQ, Watanabe M, Liner A, Hoit B, Voelkel N, Gerson S, Hasty P, Matsuyama S. Bax deficiency extends the survival of Ku70 knockout mice that develop lung and heart diseases. Cell Death Dis 2015; 6:e1706. [PMID: 25811803 PMCID: PMC4385910 DOI: 10.1038/cddis.2015.11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Revised: 12/24/2014] [Accepted: 12/29/2014] [Indexed: 01/13/2023]
Abstract
Ku70 (Lupus Ku autoantigen p70) is essential in nonhomologous end joining DNA double-strand break repair, and ku70−/− mice age prematurely because of increased genomic instability and DNA damage responses. Previously, we found that Ku70 also inhibits Bax, a key mediator of apoptosis. We hypothesized that Bax-mediated apoptosis would be enhanced in the absence of Ku70 and contribute to premature death observed in ku70−/− mice. Here, we show that ku70−/−bax+/− and ku70−/−bax−/− mice have better survival, especially in females, than ku70−/− mice, even though Bax deficiency did not decrease the incidence of lymphoma observed in a Ku70-null background. Moreover, we found that ku70−/− mice develop lung diseases, like emphysema and pulmonary arterial (PA) occlusion, by 3 months of age. These lung abnormalities can trigger secondary health problems such as heart failure that may account for the poor survival of ku70−/− mice. Importantly, Bax deficiency appeared to delay the development of emphysema. This study suggests that enhanced Bax activity exacerbates the negative impact of Ku70 deletion. Furthermore, the underlying mechanisms of emphysema and pulmonary hypertension due to PA occlusion are not well understood, and therefore ku70−/− and Bax-deficient ku70−/− mice may be useful models to study these diseases.
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Affiliation(s)
- J Ngo
- 1] Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA [2] Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - M Matsuyama
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - C Kim
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - I Poventud-Fuentes
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - A Bates
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - S L Siedlak
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - H-G Lee
- Department of Pathology, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - Y Q Doughman
- Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - M Watanabe
- 1] Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA [2] Department of Pediatrics, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - A Liner
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - B Hoit
- Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - N Voelkel
- Pulmonary and Critical Care Medicine Division and Victoria Johnson Center for Pulmonary Obstructive Research, Virginia Commonwealth University, Richmond, VA, USA
| | - S Gerson
- 1] Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA [2] Department of Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
| | - P Hasty
- Department of Molecular Medicine and Institute of Biotechnology, University of Texas Health Science Center, San Antonio, TX, USA
| | - S Matsuyama
- 1] Department of Medicine, School of Medicine, Case Western Reserve University, Cleveland, OH, USA [2] Department of Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
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Kosova AA, Lavrik OI, Khodyreva SN. Role of Ku antigen in the repair of apurinic/apyrimidinic sites in DNA. Mol Biol 2015. [DOI: 10.1134/s0026893315010070] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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7
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Hasty P, Montagna C. Chromosomal Rearrangements in Cancer: Detection and potential causal mechanisms. Mol Cell Oncol 2014; 1:e29904. [PMID: 26203462 PMCID: PMC4507279 DOI: 10.4161/mco.29904] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 06/20/2014] [Accepted: 06/23/2014] [Indexed: 12/13/2022]
Abstract
Many cancers exhibit chromosomal rearrangements. These rearrangements can be simple with a single balanced fusion preserving the proper complement of genetic information or they can be complex with one or more fusions that distort this balance. A range of technological advances has improved our ability to detect and understand these rearrangements leading to speculation of causal mechanisms including defective DNA double strand break (DSB) repair and faulty DNA replication. A better understanding of these potential cancer-causing mechanisms will lead to novel therapeutic regimes to fight cancer. This review describes the technological advances used to detect simple and complex chromosomal rearrangements, cancers that exhibit these rearrangements, potential mechanisms that rearrange chromosomes and intervention strategies designed to specifically attack fusion gene products and causal DNA repair/synthesis pathways.
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Affiliation(s)
- Paul Hasty
- Department of Molecular Medicine/Institute of Biotechnology; The University of Texas Health Science Center at San Antonio; San Antonio, TX USA
| | - Cristina Montagna
- Department of Genetics and Pathology; Albert Einstein College of Medicine of Yeshiva University; Michael F. Price Center; Bronx, NY USA
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The progeroid phenotype of Ku80 deficiency is dominant over DNA-PKCS deficiency. PLoS One 2014; 9:e93568. [PMID: 24740260 PMCID: PMC3989187 DOI: 10.1371/journal.pone.0093568] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 03/05/2014] [Indexed: 01/01/2023] Open
Abstract
Ku80 and DNA-PKCS are both involved in the repair of double strand DNA breaks via the nonhomologous end joining (NHEJ) pathway. While ku80-/- mice exhibit a severely reduced lifespan and size, this phenotype is less pronounced in dna-pkcs-/- mice. However, these observations are based on independent studies with varying genetic backgrounds. Here, we generated ku80-/-, dna-pkcs-/- and double knock out mice in a C57Bl6/J*FVB F1 hybrid background and compared their lifespan, end of life pathology and mutation frequency in liver and spleen using a lacZ reporter. Our data confirm that inactivation of Ku80 and DNA-PKCS causes reduced lifespan and bodyweights, which is most severe in ku80-/- mice. All mutant mice exhibited a strong increase in lymphoma incidence as well as other aging-related pathology (skin epidermal and adnexal atrophy, trabacular bone reduction, kidney tubular anisokaryosis, and cortical and medullar atrophy) and severe lymphoid depletion. LacZ mutation frequency analysis did not show strong differences in mutation frequencies between knock out and wild type mice. The ku80-/- mice had the most severe phenotype and the Ku80-mutation was dominant over the DNA-PKCS-mutation. Presumably, the more severe degenerative effect of Ku80 inactivation on lifespan compared to DNA-PKCS inactivation is caused by additional functions of Ku80 or activity of free Ku70 since both Ku80 and DNA-PKCS are essential for NHEJ.
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9
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Deletion of individual Ku subunits in mice causes an NHEJ-independent phenotype potentially by altering apurinic/apyrimidinic site repair. PLoS One 2014; 9:e86358. [PMID: 24466051 PMCID: PMC3900520 DOI: 10.1371/journal.pone.0086358] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 12/07/2013] [Indexed: 01/25/2023] Open
Abstract
Ku70 and Ku80 form a heterodimer called Ku that forms a holoenzyme with DNA dependent-protein kinase catalytic subunit (DNA-PKCS) to repair DNA double strand breaks (DSBs) through the nonhomologous end joining (NHEJ) pathway. As expected mutating these genes in mice caused a similar DSB repair-defective phenotype. However, ku70-/- cells and ku80-/- cells also appeared to have a defect in base excision repair (BER). BER corrects base lesions, apurinic/apyrimidinic (AP) sites and single stand breaks (SSBs) utilizing a variety of proteins including glycosylases, AP endonuclease 1 (APE1) and DNA Polymerase β (Pol β). In addition, deleting Ku70 was not equivalent to deleting Ku80 in cells and mice. Therefore, we hypothesized that free Ku70 (not bound to Ku80) and/or free Ku80 (not bound to Ku70) possessed activity that influenced BER. To further test this hypothesis we performed two general sets of experiments. The first set showed that deleting either Ku70 or Ku80 caused an NHEJ-independent defect. We found ku80-/- mice had a shorter life span than dna-pkcs-/- mice demonstrating a phenotype that was greater than deleting the holoenzyme. We also found Ku70-deletion induced a p53 response that reduced the level of small mutations in the brain suggesting defective BER. We further confirmed that Ku80-deletion impaired BER via a mechanism that was not epistatic to Pol β. The second set of experiments showed that free Ku70 and free Ku80 could influence BER. We observed that deletion of either Ku70 or Ku80, but not both, increased sensitivity of cells to CRT0044876 (CRT), an agent that interferes with APE1. In addition, free Ku70 and free Ku80 bound to AP sites and in the case of Ku70 inhibited APE1 activity. These observations support a novel role for free Ku70 and free Ku80 in altering BER.
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10
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Li H, Marple T, Hasty P. Ku80-deleted cells are defective at base excision repair. Mutat Res 2013; 745-746:16-25. [PMID: 23567907 DOI: 10.1016/j.mrfmmm.2013.03.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/18/2013] [Accepted: 03/29/2013] [Indexed: 11/27/2022]
Abstract
Ku80 forms a heterodimer with Ku70, called Ku, that repairs DNA double-strand breaks (DSBs) via the nonhomologous end joining (NHEJ) pathway. As a consequence of deleting NHEJ, Ku80-mutant cells are hypersensitive to agents that cause DNA DSBs like ionizing radiation. Here we show that Ku80 deletion also decreased resistance to ROS and alkylating agents that typically cause base lesions and single-strand breaks (SSBs). This is unusual since base excision repair (BER), not NHEJ, typically repairs these types of lesions. However, we show that deletion of another NHEJ protein, DNA ligase IV (Lig4), did not cause hypersensitivity to these agents. In addition, the ROS and alkylating agents did not induce γ-H2AX foci that are diagnostic of DSBs. Furthermore, deletion of Ku80, but not Lig4 or Ku70, reduced BER capacity. Ku80 deletion also impaired BER at the initial lesion recognition/strand scission step; thus, involvement of a DSB is unlikely. Therefore, our data suggests that Ku80 deletion impairs BER via a mechanism that does not repair DSBs.
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Affiliation(s)
- Han Li
- The Department of Molecular Medicine, The University of Texas Health Science Center, San Antonio, TX 78245-3207, USA
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11
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Agrobacterium tumefaciens T-DNA Integration and Gene Targeting in Arabidopsis thaliana Non-Homologous End-Joining Mutants. ACTA ACUST UNITED AC 2012. [DOI: 10.1155/2012/989272] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In order to study the role of AtKu70 and AtKu80 in Agrobacterium-mediated transformation and gene targeting, plant lines with a T-DNA insertion in AtKu80 or AtKu70 genes were functionally characterized. Such plant lines lacked both subunits, indicating that heterodimer formation between AtKu70 and AtKu80 is needed for the stability of the proteins. Homozygous mutants were phenotypically indistinguishable from wild-type plants and were fertile. However, they were hypersensitive to the genotoxic agent bleomycin, resulting in more DSBs as quantified in comet assays. They had lower end-joining efficiency, suggesting that NHEJ is a critical pathway for DSB repair in plants. Both Atku mutants and a previously isolated Atmre11 mutant were impaired in Agrobacterium T-DNA integration via floral dip transformation, indicating that AtKu70, AtKu80, and AtMre11 play an important role in T-DNA integration in Arabidopsis. The frequency of gene targeting was not significantly increased in the Atku80 and Atku70 mutants, but it was increased at least 10-fold in the Atmre11 mutant compared with the wild type.
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12
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Freitas AA, de Magalhães JP. A review and appraisal of the DNA damage theory of ageing. Mutat Res 2011; 728:12-22. [PMID: 21600302 DOI: 10.1016/j.mrrev.2011.05.001] [Citation(s) in RCA: 137] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2011] [Revised: 05/02/2011] [Accepted: 05/03/2011] [Indexed: 01/25/2023]
Abstract
Given the central role of DNA in life, and how ageing can be seen as the gradual and irreversible breakdown of living systems, the idea that damage to the DNA is the crucial cause of ageing remains a powerful one. DNA damage and mutations of different types clearly accumulate with age in mammalian tissues. Human progeroid syndromes resulting in what appears to be accelerated ageing have been linked to defects in DNA repair or processing, suggesting that elevated levels of DNA damage can accelerate physiological decline and the development of age-related diseases not limited to cancer. Higher DNA damage may trigger cellular signalling pathways, such as apoptosis, that result in a faster depletion of stem cells, which in turn contributes to accelerated ageing. Genetic manipulations of DNA repair pathways in mice further strengthen this view and also indicate that disruption of specific pathways, such as nucleotide excision repair and non-homologous end joining, is more strongly associated with premature ageing phenotypes. Delaying ageing in mice by decreasing levels of DNA damage, however, has not been achieved yet, perhaps due to the complexity inherent to DNA repair and DNA damage response pathways. Another open question is whether DNA repair optimization is involved in the evolution of species longevity, and we suggest that the way cells from different organisms respond to DNA damage may be crucial in species differences in ageing. Taken together, the data suggest a major role of DNA damage in the modulation of longevity, possibly through effects on cell dysfunction and loss, although understanding how to modify DNA damage repair and response systems to delay ageing remains a crucial challenge.
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Affiliation(s)
- Alex A Freitas
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool, L69 7ZB, UK; School of Computing and Centre for BioMedical Informatics, University of Kent, Canterbury, CT2 7NF, UK.
| | - João Pedro de Magalhães
- Integrative Genomics of Ageing Group, Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, Liverpool, L69 7ZB, UK.
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Li R, Yang Y, An Y, Zhou Y, Liu Y, Yu Q, Lu D, Wang H, Jin L, Zhou W, Qian J, Shugart YY. Genetic polymorphisms in DNA double-strand break repair genes XRCC5, XRCC6 and susceptibility to hepatocellular carcinoma. Carcinogenesis 2011; 32:530-6. [PMID: 21304054 DOI: 10.1093/carcin/bgr018] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Environmental risk factors cause DNA damages. Imprecise DNA repair leads to chromosome aberrations, genome destabilization and hepatocarcinogenesis. Ku is a key DNA double-strand break repair protein. We hypothesized that the genetic variants in Ku subunits encoding genes, XRCC5/XRCC6, may contribute to hepatocellular carcinoma (HCC) susceptibility. We genotyped 13 common single nucleotide polymorphisms (SNPs) in XRCC5 and XRCC6 and evaluated their associations with HCC risk in 689 pathologically confirmed cases and 690 cancer-free controls from a Chinese population. We found that a significantly reduced risk for HCC was associated with XRCC5 rs16855458 [odds ratio (OR)=0.59; 95% confidence interval (CI)=0.43-0.81; CA+AA versus CC] and a significantly increased risk for HCC was associated with XRCC5 rs9288516 (OR=2.02; 95% CI=1.42-2.86; TA+AA versus TT) even after Bonferroni correction (Pcorrected=0.026 and 0.002, respectively). The effects of rs16855458 (OR=0.57; 95% CI=0.37-0.86, P=0.008) and rs9288516 (OR=1.86; 95% CI=1.19-2.90, P=0.007) were more significant in hepatitis B surface antigen-infected subjects than non-infected subjects. The haplotype-based analysis revealed that in XRCC5, AA in block 1 (OR=0.63; 95% CI=0.48-0.83) and CGGTT in block 2 (OR=0.52; 95% CI=0.39-0.69) were associated with decreased HCC risk (Pcorrected=0.013 and <0.001, respectively). The aforementioned two SNPs exhibited a significant cumulative risk effect (Ptrend<0.001). Additionally, potential interaction among XRCC5 rs9288516 and rs2267437, rs5751131 in XRCC6 was indicated by the multifactor dimensionality reduction analysis. In conclusion, XRCC5 variants may play a role in determining individual's HCC susceptibility, which warranted validation in larger studies.
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Affiliation(s)
- Rui Li
- State Key Laboratory of Genetic Engineering, School of Life Sciences and Institutes of Biomedical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 China
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Brenkman AB, Broek NJF, Keizer PLJ, Gent DC, Burgering BMT. The DNA damage repair protein Ku70 interacts with FOXO4 to coordinate a conserved cellular stress response. FASEB J 2010; 24:4271-80. [DOI: 10.1096/fj.10-158717] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Arjan B. Brenkman
- Department of Physiological ChemistryUniversity Medical Centre Utrecht Utrecht The Netherlands
- Centre for Biomedical GeneticsUniversity Medical Centre Utrecht Utrecht The Netherlands
- Department of Metabolic and Endocrine DiseasesUniversity Medical Centre Utrecht Utrecht The Netherlands
- Netherlands Metabolomics Centre Utrecht The Netherlands
| | - Niels J. F. Broek
- Centre for Biomedical GeneticsUniversity Medical Centre Utrecht Utrecht The Netherlands
- Department of Metabolic and Endocrine DiseasesUniversity Medical Centre Utrecht Utrecht The Netherlands
- Netherlands Metabolomics Centre Utrecht The Netherlands
| | - Peter L. J. Keizer
- Department of Physiological ChemistryUniversity Medical Centre Utrecht Utrecht The Netherlands
- Centre for Biomedical GeneticsUniversity Medical Centre Utrecht Utrecht The Netherlands
| | - Dik C. Gent
- Department of Cell Biology and GeneticsErasmus Medical CenterUniversity Medical Center Rotterdam Rotterdam The Netherlands
| | - Boudewijn M. T. Burgering
- Department of Physiological ChemistryUniversity Medical Centre Utrecht Utrecht The Netherlands
- Centre for Biomedical GeneticsUniversity Medical Centre Utrecht Utrecht The Netherlands
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Ku is a 5'-dRP/AP lyase that excises nucleotide damage near broken ends. Nature 2010; 464:1214-7. [PMID: 20383123 PMCID: PMC2859099 DOI: 10.1038/nature08926] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2008] [Accepted: 02/11/2010] [Indexed: 01/08/2023]
Abstract
Mammalian cells require Nonhomologous end joining (NHEJ) for efficient repair of chromosomal DNA double-strand breaks1. A key feature of biological sources of strand breaks is associated nucleotide damage, including base loss (abasic or AP sites)2. At single strand breaks, 5' terminal abasic sites are excised by pol β's 5'dRP lyase activity3,4,5,6: we show here in vitro and in cells that accurate and efficient repair by NHEJ of double-strand breaks with such damage similarly requires 5'dRP/AP lyase activity (Figure 1a). Classically defined NHEJ is moreover uniquely effective at coupling this end-cleaning step to joining in cells, helping distinguish this pathway from otherwise robust alternate NHEJ pathways. Surprisingly, the NHEJ factor Ku can be identified as an effective 5'dRP/AP lyase. Similar to other lyases7, Ku nicks DNA 3' of an abasic site by a mechanism involving a Schiff base covalent intermediate with the abasic site. We demonstrate using cell extracts that Ku is essential for efficient removal of AP sites near double-strand breaks and, consistent with this result, joining of such breaks is specifically reduced in cells complemented with a lyase-attenuated Ku mutant. Ku had previously been presumed only to recognize ends and recruit other factors that processed ends; our data supports an unexpected direct role for Ku in end processing steps as well.
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