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Gao L, Zhang X, Cui J, Liu L, Tai D, Wang S, Huang L. Transcription factor TP63 mediates LncRNA CNTFR-AS1 to promote DNA damage induced by neodymium oxide nanoparticles via homologous recombination repair. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2023; 334:122191. [PMID: 37451587 DOI: 10.1016/j.envpol.2023.122191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 06/21/2023] [Accepted: 07/11/2023] [Indexed: 07/18/2023]
Abstract
The widespread use of neodymium oxide nanoparticles (NPs-Nd2O3) has caused environmental pollution and human health problems, thus attracting significant attention. Understanding the mechanisms of NPs- Nd2O3-induced genetic damage is of great significance for identifying early markers for NPs- Nd2O3-induced lung injury. At present, the mechanisms underlying DNA damage induced by NPs- Nd2O3 remain unclear. In this study, we performed functional assays on human bronchial epithelial cells (16HBEs) exposed to various concentrations of NPs-Nd2O3 and SD rats administered with a single intratracheal instillation with NPs-Nd2O3. Exposure to NPs-Nd2O3 could lead to DNA damage in 16HBE cells and rat lung tissue cells. We found a novel long non-coding RNA, named CNTFR-AS1, which was highly expressed after exposure to NPs-Nd2O3. Our data verified that transcription factor TP63 mediates the high expression levels of CNTFR-AS1, which in turn regulates NPs-Nd2O3-induced DNA damage in cells by inhibiting HR repair. Moreover, the levels of CNTFR-AS1 were correlated with the number of years worked by occupational workers. Collectively, these results demonstrate that CNTFR-AS1 acts as a novel DNA damage regulator in bronchial epithelial cells exposed to NPs-Nd2O3. Hence, our data provide a basis for the identification of lncRNAs as early diagnostic markers for rare earth lung injury.
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Affiliation(s)
- Lei Gao
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Xia Zhang
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Jinjin Cui
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Ling Liu
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Dapeng Tai
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Suhua Wang
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China
| | - Lihua Huang
- School of Public Health, Baotou Medical College, Baotou, 014030, Inner Mongolia, China.
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2
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Lu H, Zhang Q, Laverty DJ, Puncheon AC, Augustine M, Williams G, Nagel Z, Chen BC, Davis A. ATM phosphorylates the FATC domain of DNA-PKcs at threonine 4102 to promote non-homologous end joining. Nucleic Acids Res 2023; 51:6770-6783. [PMID: 37309889 PMCID: PMC10359628 DOI: 10.1093/nar/gkad505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 05/26/2023] [Accepted: 05/31/2023] [Indexed: 06/14/2023] Open
Abstract
Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double-stranded breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Ablating phosphorylation at T4102 attenuates DNA-PKcs kinase activity and this destabilizes the interaction between DNA-PKcs and the Ku-DNA complex, resulting in decreased assembly and stabilization of the NHEJ machinery at DSBs. Phosphorylation at T4102 promotes NHEJ, radioresistance, and increases genomic stability following DSB induction. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PKcs.
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Affiliation(s)
- Huiming Lu
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Qin Zhang
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Daniel J Laverty
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA02115, USA
| | - Andrew C Puncheon
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Mathew M Augustine
- Division of Surgical Oncology, Department of Surgery, UT Southwestern Medical Center, Dallas, TX75390, USA
- Department of Surgery, North Texas VA Medical Center, Dallas, TX75216, USA
| | - Gareth J Williams
- Department of Biochemistry and Molecular Biology, Robson DNA Science Centre, Charbonneau Cancer Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Zachary D Nagel
- Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA02115, USA
| | - Benjamin P C Chen
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
| | - Anthony J Davis
- Department of Radiation Oncology, UT Southwestern Medical Center, Dallas, TX75390, USA
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3
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Lu H, Zhang Q, Laverty DJ, Puncheon AC, Williams GJ, Nagel ZD, Chen BP, Davis AJ. ATM phosphorylates the FATC domain of DNA-PK cs at threonine 4102 to promote non-homologous end joining. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.02.526879. [PMID: 36778257 PMCID: PMC9915669 DOI: 10.1101/2023.02.02.526879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Ataxia-telangiectasia mutated (ATM) drives the DNA damage response via modulation of multiple signal transduction and DNA repair pathways. Previously, ATM activity was implicated in promoting the non-homologous end joining (NHEJ) pathway to repair a subset of DNA double strand breaks (DSBs), but how ATM performs this function is still unclear. In this study, we identified that ATM phosphorylates the DNA-dependent protein kinase catalytic subunit (DNA-PK cs ), a core NHEJ factor, at its extreme C-terminus at threonine 4102 (T4102) in response to DSBs. Phosphorylation at T4102 stabilizes the interaction between DNA-PK cs and the Ku-DNA complex and promotes assembly and stabilization of the NHEJ machinery at DSBs. Ablating phosphorylation at this site results in decreased NHEJ, radiosensitivity, and increased radiation-induced genomic instability. Collectively, these findings establish a key role for ATM in NHEJ-dependent repair of DSBs through positive regulation of DNA-PK cs .
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de Campos Nebel M, Palmitelli M, Pérez Maturo J, González-Cid M. Alternative end-joining originates stable chromosome aberrations induced by etoposide during targeted inhibition of DNA-PKcs in ATM-deficient tumor cells. Chromosome Res 2022; 30:459-476. [PMID: 35604590 DOI: 10.1007/s10577-022-09700-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Revised: 04/29/2022] [Accepted: 05/09/2022] [Indexed: 01/25/2023]
Abstract
ATM and DNA-PKcs coordinate the DNA damage response at multiple levels following the exposure to chemotherapy. The Topoisomerase II poison etoposide (ETO) is an effective chemotherapeutic agent that induces DNA double-strand breaks (DSB), but it is responsible from the chromosomal rearrangements frequently found in therapy-related secondary tumors. Targeted inhibition of DNA-PKcs in ATM-defective tumors combined with radio- or chemotherapy has been proposed as relevant therapies. Here, we explored the DNA repair mechanisms and the genetic consequences of targeting the non-oncogenic addiction to DNA-PKcs of ATM-defective tumor cells after exposure to ETO. We demonstrated that chemical inhibition of DNA-PKcs followed by treatment with ETO resulted in the accumulation of chromatid breaks and decreased mitotic index in both A-T cells and ATM-knocked-down (ATMkd) tumor cells. The HR repair process in DNA-PKcs-inhibited ATMkd cells amplified the RAD51 foci number, with no correlated increase in sister chromatid exchanges. The analysis of post-mitotic DNA lesions presented an augmented number of persistent unresolved DSB, without alterations in the cell cycle progression. Long-term examination of chromosome aberrations revealed a strikingly high number of chromatid and chromosome exchanges. By using genetic and pharmacological abrogation of PARP-1, we demonstrated that alternative end-joining (alt-EJ) repair pathway is responsible for those chromosome abnormalities generated by limiting c-NHEJ activities during directed inhibition of DNA-PKcs in ATM-deficient cells. Targeting the non-oncogenic addiction to DNA-PKcs of ATM-defective tumors stimulates the DSB repair by alt-EJ, which is liable for the origin of cells carrying stable chromosome aberrations that may eventually restrict the therapeutic strategy.
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Affiliation(s)
- Marcelo de Campos Nebel
- Laboratorio de Mutagénesis, Instituto de Medicina Experimental (IMEX), CONICET-Academia Nacional de Medicina, Buenos Aires, Argentina.
| | - Micaela Palmitelli
- Laboratorio de Mutagénesis, Instituto de Medicina Experimental (IMEX), CONICET-Academia Nacional de Medicina, Buenos Aires, Argentina
| | - Josefina Pérez Maturo
- Programa de Medicina de Precisión Y Genómica Clínica, Facultad de Ciencias Biomédicas,, Instituto de Investigaciones en Medicina Traslacional, Universidad Austral-CONICET, Pilar, Argentina
- Consultorio Y Laboratorio de Neurogenética, Facultad de Medicina, Centro Universitario de Neurología "José María Ramos Mejía" Y División Neurología, Hospital J.M. Ramos Mejía, Universidad de Buenos Aires, Buenos Aires,, Argentina
| | - Marcela González-Cid
- Laboratorio de Mutagénesis, Instituto de Medicina Experimental (IMEX), CONICET-Academia Nacional de Medicina, Buenos Aires, Argentina
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Anglada T, Repullés J, Espinal A, LaBarge MA, Stampfer MR, Genescà A, Martín M. Delayed γH2AX foci disappearance in mammary epithelial cells from aged women reveals an age-associated DNA repair defect. Aging (Albany NY) 2020; 11:1510-1523. [PMID: 30875333 PMCID: PMC6428106 DOI: 10.18632/aging.101849] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 03/09/2019] [Indexed: 01/15/2023]
Abstract
Aging is a degenerative process in which genome instability plays a crucial role. To gain insight into the link between organismal aging and DNA repair capacity, we analyzed DNA double-strand break (DSB) resolution efficiency in human mammary epithelial cells from 12 healthy donors of young and old ages. The frequency of DSBs was measured by quantifying the number of γH2AX foci before and after 1Gy of γ-rays and it was higher in cells from aged donors (ADs) at all times analyzed. At 24 hours after irradiation, ADs retained a significantly higher frequency of residual DSBs than young donors (YDs), which had already reached values close to basal levels. The kinetics of DSB induction and disappearance showed that cells from ADs and YDs repair DSBs with similar speed, although analysis of early times after irradiation indicate that a repair defect may lie within the firing of the DNA repair machinery in AD cells. Indeed, using a mathematical model we calculated a constant factor of delay affecting aged human epithelial cells repair kinetics. This defect manifests with the accumulation of DSBs that might eventually undergo illegitimate repair, thus posing a relevant threat to the maintenance of genome integrity in older individuals.
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Affiliation(s)
- Teresa Anglada
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Joan Repullés
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain.,Microscopy Platform, Biomedical Research Institute Sant Pau (IIB-Sant Pau), Barcelona, 08041, Spain
| | - Anna Espinal
- Servei d'Estadística Aplicada, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Mark A LaBarge
- Department of Population Sciences, and Center for Cancer and Aging, Beckman Research Institute at City of Hope, Duarte, CA, 91010, USA.,Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Martha R Stampfer
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Anna Genescà
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
| | - Marta Martín
- Department of Cell Biology, Physiology and Immunology, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain
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6
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Priya B, Spadigam A, Dhupar A, Syed S. Frequency of micronuclei in tobacco habitués and Non-Habitués with oral lichen planus. CHRISMED JOURNAL OF HEALTH AND RESEARCH 2020. [DOI: 10.4103/cjhr.cjhr_109_1910.4103/cjhr.cjhr_109_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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7
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Hollingworth R, Horniblow RD, Forrest C, Stewart GS, Grand RJ. Localization of Double-Strand Break Repair Proteins to Viral Replication Compartments following Lytic Reactivation of Kaposi's Sarcoma-Associated Herpesvirus. J Virol 2017; 91:e00930-17. [PMID: 28855246 PMCID: PMC5660498 DOI: 10.1128/jvi.00930-17] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 08/10/2017] [Indexed: 12/11/2022] Open
Abstract
Double-strand breaks (DSBs) in DNA are recognized by the Ku70/80 heterodimer and the MRE11-RAD50-NBS1 (MRN) complex and result in activation of the DNA-PK and ATM kinases, which play key roles in regulating the cellular DNA damage response (DDR). DNA tumor viruses such as Kaposi's sarcoma-associated herpesvirus (KSHV) are known to interact extensively with the DDR during the course of their replicative cycles. Here we show that during lytic amplification of KSHV DNA, the Ku70/80 heterodimer and the MRN complex consistently colocalize with viral genomes in replication compartments (RCs), whereas other DSB repair proteins form foci outside RCs. Depletion of MRE11 and abrogation of its exonuclease activity negatively impact viral replication, while in contrast, knockdown of Ku80 and inhibition of the DNA-PK enzyme, which are involved in nonhomologous end joining (NHEJ) repair, enhance amplification of viral DNA. Although the recruitment of DSB-sensing proteins to KSHV RCs is a consistent occurrence across multiple cell types, activation of the ATM-CHK2 pathway during viral replication is a cell line-specific event, indicating that recognition of viral DNA by the DDR does not necessarily result in activation of downstream signaling pathways. We have also observed that newly replicated viral DNA is not associated with cellular histones. Since the presence and modification of these DNA-packaging proteins provide a scaffold for docking of multiple DNA repair factors, the absence of histone deposition may allow the virus to evade localization of DSB repair proteins that would otherwise have a detrimental effect on viral replication.IMPORTANCE Tumor viruses are known to interact with machinery responsible for detection and repair of double-strand breaks (DSBs) in DNA, although detail concerning how Kaposi's sarcoma-associated herpesvirus (KSHV) modulates these cellular pathways during its lytic replication phase was previously lacking. By undertaking a comprehensive assessment of the localization of DSB repair proteins during KSHV replication, we have determined that a DNA damage response (DDR) is directed to viral genomes but is distinct from the response to cellular DNA damage. We also demonstrate that although recruitment of the MRE11-RAD50-NBS1 (MRN) DSB-sensing complex to viral genomes and activation of the ATM kinase can promote KSHV replication, proteins involved in nonhomologous end joining (NHEJ) repair restrict amplification of viral DNA. Overall, this study extends our understanding of the virus-host interactions that occur during lytic replication of KSHV and provides a deeper insight into how the DDR is manipulated during viral infection.
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Affiliation(s)
- Robert Hollingworth
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Richard D Horniblow
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Calum Forrest
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Grant S Stewart
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
| | - Roger J Grand
- Institute of Cancer and Genomic Sciences, University of Birmingham, Birmingham, United Kingdom
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8
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Kramer N, Rosner M, Kovacic B, Hengstschläger M. Full biological characterization of human pluripotent stem cells will open the door to translational research. Arch Toxicol 2016; 90:2173-2186. [PMID: 27325309 DOI: 10.1007/s00204-016-1763-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Accepted: 06/13/2016] [Indexed: 12/13/2022]
Abstract
Since the discovery of human embryonic stem cells (hESC) and human-induced pluripotent stem cells (hiPSC), great hopes were held for their therapeutic application including disease modeling, drug discovery screenings, toxicological screenings and regenerative therapy. hESC and hiPSC have the advantage of indefinite self-renewal, thereby generating an inexhaustible pool of cells with, e.g., specific genotype for developing putative treatments; they can differentiate into derivatives of all three germ layers enabling autologous transplantation, and via donor-selection they can express various genotypes of interest for better disease modeling. Furthermore, drug screenings and toxicological screenings in hESC and hiPSC are more pertinent to identify drugs or chemical compounds that are harmful for human, than a mouse model could predict. Despite continuing research in the wide field of therapeutic applications, further understanding of the underlying basic mechanisms of stem cell function is necessary. Here, we summarize current knowledge concerning pluripotency, self-renewal, apoptosis, motility, epithelial-to-mesenchymal transition and differentiation of pluripotent stem cells.
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Affiliation(s)
- Nina Kramer
- Institute of Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090, Vienna, Austria
| | - Margit Rosner
- Institute of Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090, Vienna, Austria
| | - Boris Kovacic
- Institute of Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090, Vienna, Austria
| | - Markus Hengstschläger
- Institute of Medical Genetics, Medical University of Vienna, Währingerstrasse 10, 1090, Vienna, Austria.
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9
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The Vitamin A Derivative All-Trans Retinoic Acid Repairs Amyloid-β-Induced Double-Strand Breaks in Neural Cells and in the Murine Neocortex. Neural Plast 2016; 2016:3707406. [PMID: 26881107 PMCID: PMC4735929 DOI: 10.1155/2016/3707406] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 10/13/2015] [Indexed: 12/17/2022] Open
Abstract
The amyloid-β peptide or Aβ is the key player in the amyloid-cascade hypothesis of Alzheimer's disease. Aβ appears to trigger cell death but also production of double-strand breaks (DSBs) in aging and Alzheimer's disease. All-trans retinoic acid (RA), a derivative of vitamin A, was already known for its neuroprotective effects against the amyloid cascade. It diminishes, for instance, the production of Aβ peptides and their oligomerisation. In the present work we investigated the possible implication of RA receptor (RAR) in repair of Aβ-induced DSBs. We demonstrated that RA, as well as RAR agonist Am80, but not AGN 193109 antagonist, repair Aβ-induced DSBs in SH-SY5Y cells and an astrocytic cell line as well as in the murine cortical tissue of young and aged mice. The nonhomologous end joining pathway and the Ataxia Telangiectasia Mutated kinase were shown to be involved in RA-mediated DSBs repair in the SH-SY5Y cells. Our data suggest that RA, besides increasing cell viability in the cortex of young and even of aged mice, might also result in targeted DNA repair of genes important for cell or synaptic maintenance. This phenomenon would remain functional up to a point when Aβ increase and RA decrease probably lead to a pathological state.
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A novelly synthesized phenanthroline derivative is a promising DNA-damaging anticancer agent inhibiting G1/S checkpoint transition and inducing cell apoptosis in cancer cells. Cancer Chemother Pharmacol 2015; 77:169-80. [PMID: 26590990 DOI: 10.1007/s00280-015-2894-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 10/20/2015] [Indexed: 10/22/2022]
Abstract
PURPOSE The study mainly aimed to determine the biological function of a novelly synthesized phenanthroimidazole derivative, named L233, and to explore its potential mechanisms. METHODS Cell survival was examined using the MTT assays, and the DNA-damaging role of L233 was explored using the comet assay. Moreover, the western blotting assays and immunofluorescence assays were used to detect DNA damage biomarkers. Afterward, the flow cytometry was used to assess the effects of L233 on cell cycle distribution. As for the detection of cell apoptosis upon L233 treatment, the Hoechst 33342 staining, flow cytometry, and western blotting assays were all put into practice. RESULTS We find that L233 inhibits tumor cell growth more efficiently and safely than cisplatin. Moreover, it is a DNA-damaging agent, interrupting the cell cycle G1/S checkpoint transition and inducing cell apoptosis by not only activating ATM/CHK1 signaling pathway, but also targeting CHK1 to reduce the expression of RAP80 and PARP-1 to compromise the DNA damage repair in tumor cells. CONCLUSIONS In summary, L233 is a promising anticancer drug for the development of novel chemotherapies in the future.
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Björkman A, Du L, Felgentreff K, Rosner C, Pankaj Kamdar R, Kokaraki G, Matsumoto Y, Davies EG, van der Burg M, Notarangelo LD, Hammarström L, Pan-Hammarström Q. DNA-PKcs Is Involved in Ig Class Switch Recombination in Human B Cells. THE JOURNAL OF IMMUNOLOGY 2015; 195:5608-15. [DOI: 10.4049/jimmunol.1501633] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Accepted: 10/06/2015] [Indexed: 01/03/2023]
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Gustafsson AS, Abramenkovs A, Stenerlöw B. Suppression of DNA-dependent protein kinase sensitize cells to radiation without affecting DSB repair. Mutat Res 2014; 769:1-10. [PMID: 25771720 DOI: 10.1016/j.mrfmmm.2014.06.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 06/04/2014] [Accepted: 06/16/2014] [Indexed: 06/04/2023]
Abstract
Efficient and correct repair of DNA double-strand break (DSB) is critical for cell survival. Defects in the DNA repair may lead to cell death, genomic instability and development of cancer. The catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) is an essential component of the non-homologous end joining (NHEJ) which is the major DSB repair pathway in mammalian cells. In the present study, by using siRNA against DNA-PKcs in four human cell lines, we examined how low levels of DNA-PKcs affected cellular response to ionizing radiation. Decrease of DNA-PKcs levels by 80-95%, induced by siRNA treatment, lead to extreme radiosensitivity, similar to that seen in cells completely lacking DNA-PKcs and low levels of DNA-PKcs promoted cell accumulation in G2/M phase after irradiation and blocked progression of mitosis. Surprisingly, low levels of DNA-PKcs did not affect the repair capacity and the removal of 53BP1 or γ-H2AX foci and rejoining of DSB appeared normal. This was in strong contrast to cells completely lacking DNA-PKcs and cells treated with the DNA-PKcs inhibitor NU7441, in which DSB repair were severely compromised. This suggests that there are different mechanisms by which loss of DNA-PKcs functions can sensitize cells to ionizing radiation. Further, foci of phosphorylated DNA-PKcs (T2609 and S2056) co-localized with DSB and this was independent of the amount of DNA-PKcs but foci of DNA-PKcs was only seen in siRNA-treated cells. Our study emphasizes on the critical role of DNA-PKcs for maintaining survival after radiation exposure which is uncoupled from its essential function in DSB repair. This could have implications for the development of therapeutic strategies aiming to radiosensitize tumors by affecting the DNA-PKcs function.
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Affiliation(s)
- Ann-Sofie Gustafsson
- Section of Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Science, Rudbeck Laboratory, Uppsala University, Dag Hammarskjölds Väg 20, SE-751 85 Uppsala, Sweden.
| | - Andris Abramenkovs
- Section of Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Science, Rudbeck Laboratory, Uppsala University, Dag Hammarskjölds Väg 20, SE-751 85 Uppsala, Sweden
| | - Bo Stenerlöw
- Section of Biomedical Radiation Sciences, Department of Radiology, Oncology and Radiation Science, Rudbeck Laboratory, Uppsala University, Dag Hammarskjölds Väg 20, SE-751 85 Uppsala, Sweden
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13
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A novel ATM/TP53/p21-mediated checkpoint only activated by chronic γ-irradiation. PLoS One 2014; 9:e104279. [PMID: 25093836 PMCID: PMC4122452 DOI: 10.1371/journal.pone.0104279] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/05/2014] [Indexed: 01/19/2023] Open
Abstract
Different levels or types of DNA damage activate distinct signaling pathways that elicit various cellular responses, including cell-cycle arrest, DNA repair, senescence, and apoptosis. Whereas a range of DNA-damage responses have been characterized, mechanisms underlying subsequent cell-fate decision remain elusive. Here we exposed cultured cells and mice to different doses and dose rates of γ-irradiation, which revealed cell-type-specific sensitivities to chronic, but not acute, γ-irradiation. Among tested cell types, human fibroblasts were associated with the highest levels of growth inhibition in response to chronic γ-irradiation. In this context, fibroblasts exhibited a reversible G1 cell-cycle arrest or an irreversible senescence-like growth arrest, depending on the irradiation dose rate or the rate of DNA damage. Remarkably, when the same dose of γ-irradiation was delivered chronically or acutely, chronic delivery induced considerably more cellular senescence. A similar effect was observed with primary cells isolated from irradiated mice. We demonstrate a critical role for the ataxia telangiectasia mutated (ATM)/tumor protein p53 (TP53)/p21 pathway in regulating DNA-damage-associated cell fate. Indeed, blocking the ATM/TP53/p21 pathway deregulated DNA damage responses, leading to micronucleus formation in chronically irradiated cells. Together these results provide insights into the mechanisms governing cell-fate determination in response to different rates of DNA damage.
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14
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Interplay of DNA damage and cell cycle signaling at the level of human replication protein A. DNA Repair (Amst) 2014; 21:12-23. [PMID: 25091156 DOI: 10.1016/j.dnarep.2014.05.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 03/17/2014] [Accepted: 05/18/2014] [Indexed: 02/05/2023]
Abstract
Replication protein A (RPA) is the main human single-stranded DNA (ssDNA)-binding protein. It is essential for cellular DNA metabolism and has important functions in human cell cycle and DNA damage signaling. RPA is indispensable for accurate homologous recombination (HR)-based DNA double-strand break (DSB) repair and its activity is regulated by phosphorylation and other post-translational modifications. HR occurs only during S and G2 phases of the cell cycle. All three subunits of RPA contain phosphorylation sites but the exact set of HR-relevant phosphorylation sites on RPA is unknown. In this study, a high resolution capillary isoelectric focusing immunoassay, used under native conditions, revealed the isoforms of the RPA heterotrimer in control and damaged cell lysates in G2. Moreover, the phosphorylation sites of chromatin-bound and cytosolic RPA in S and G2 phases were identified by western and IEF analysis with all available phosphospecific antibodies for RPA2. Strikingly, most of the RPA heterotrimers in control G2 cells are phosphorylated with 5 isoforms containing up to 7 phosphates. These isoforms include RPA2 pSer23 and pSer33. DNA damaged cells in G2 had 9 isoforms with up to 14 phosphates. DNA damage isoforms contained pSer4/8, pSer12, pThr21, pSer23, and pSer33 on RPA2 and up to 8 unidentified phosphorylation sites.
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García CP, Videla Richardson GA, Romorini L, Miriuka SG, Sevlever GE, Scassa ME. Topoisomerase I inhibitor, camptothecin, induces apoptogenic signaling in human embryonic stem cells. Stem Cell Res 2013; 12:400-14. [PMID: 24380814 DOI: 10.1016/j.scr.2013.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 11/27/2013] [Accepted: 12/04/2013] [Indexed: 01/10/2023] Open
Abstract
Embryonic stem cells (ESCs) need to maintain their genomic integrity in response to DNA damage to safeguard the integrity of the organism. DNA double strand breaks (DSBs) are one of the most lethal forms of DNA damage and, if not repaired correctly, they can lead to cell death, genomic instability and cancer. How human ESCs (hESCs) maintain genomic integrity in response to agents that cause DSBs is relatively unclear. In the present study we aim to determine the hESC response to the DSB inducing agent camptothecin (CPT). We find that hESCs are hypersensitive to CPT, as evidenced by high levels of apoptosis. CPT treatment leads to DNA-damage sensor kinase (ATM and DNA-PKcs) phosphorylation on serine 1981 and serine 2056, respectively. Activation of ATM and DNA-PKcs was followed by histone H2AX phosphorylation on Ser 139, a sensitive reporter of DNA damage. Nuclear accumulation and ATM-dependent phosphorylation of p53 on serine 15 were also observed. Remarkably, hESC viability was further decreased when ATM or DNA-PKcs kinase activity was impaired by the use of specific inhibitors. The hypersensitivity to CPT treatment was markedly reduced by blocking p53 translocation to mitochondria with pifithrin-μ. Importantly, programmed cell death was achieved in the absence of the cyclin dependent kinase inhibitor, p21(Waf1), a bona fide p53 target gene. Conversely, differentiated hESCs were no longer highly sensitive to CPT. This attenuated apoptotic response was accompanied by changes in cell cycle profile and by the presence of p21(Waf1). The results presented here suggest that p53 has a key involvement in preventing the propagation of damaged hESCs when genome is threatened. As a whole, our findings support the concept that the phenomenon of apoptosis is a prominent player in normal embryonic development.
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Affiliation(s)
- Carolina Paola García
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
| | - Guillermo Agustín Videla Richardson
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
| | - Leonardo Romorini
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
| | - Santiago Gabriel Miriuka
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
| | - Gustavo Emilio Sevlever
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
| | - María Elida Scassa
- Laboratorio de Investigación aplicada a Neurociencias-LIAN-Fundación para la Lucha contra las Enfermedades Neurológicas de la Infancia-FLENI, Ruta 9, Km 52.5, B1625XAF Escobar, Provincia de Buenos Aires, Argentina.
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Liu H, Galka M, Mori E, Liu X, Lin YF, Wei R, Pittock P, Voss C, Dhami G, Li X, Miyaji M, Lajoie G, Chen B, Li SSC. A method for systematic mapping of protein lysine methylation identifies functions for HP1β in DNA damage response. Mol Cell 2013; 50:723-35. [PMID: 23707759 DOI: 10.1016/j.molcel.2013.04.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 03/13/2013] [Accepted: 04/12/2013] [Indexed: 11/28/2022]
Abstract
Lysine methylation occurs on both histone and nonhistone proteins. However, our knowledge on the prevalence and function of nonhistone protein methylation is poor. We describe an approach that combines peptide array, bioinformatics, and mass spectrometry to systematically identify lysine methylation sites and map methyllysine-driven protein-protein interactions. Using this approach, we identified a high-confidence and high-resolution interactome of the heterochromatin protein 1β (HP1β) and uncovered, simultaneously, numerous methyllysine sites on nonhistone proteins. We found that HP1β binds to DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and regulates its localization to double-strand breaks (DSBs) during DNA damage response (DDR). Mutation of the methylation sites in DNA-PKcs or depletion of HP1β in cells caused defects in DDR. Furthermore, we showed that the methylation of DNA-PKcs and many other proteins in the HP1β interactome undergoes large changes in response to DNA damage, indicating that Lys methylation is a highly dynamic posttranslational modification.
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Affiliation(s)
- Huadong Liu
- Department of Biochemistry and the Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
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Palii SS, Cui Y, Innes CL, Paules RS. Dissecting cellular responses to irradiation via targeted disruptions of the ATM-CHK1-PP2A circuit. Cell Cycle 2013; 12:1105-18. [PMID: 23462183 DOI: 10.4161/cc.24127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Exposure of proliferating cells to genotoxic stresses activates a cascade of signaling events termed the DNA damage response (DDR). The DDR preserves genetic stability by detecting DNA lesions, activating cell cycle checkpoints and promoting DNA damage repair. The phosphoinositide 3-kinase-related kinases (PIKKs) ataxia telangiectasia-mutated (ATM), ATM and Rad 3-related kinase (ATR) and DNA-dependent protein kinase (DNA-PK) are crucial for sensing lesions and signal transduction. The checkpoint kinase 1 (CHK1) is a traditional ATR target involved in DDR and normal cell cycle progression and represents a pharmacological target for anticancer regimens. This study employed cell lines stably depleted for CHK1, ATM or both for dissecting cross-talk and compensatory effects on G(2)/M checkpoint in response to ionizing radiation (IR). We show that a 90% depletion of CHK1 renders cells radiosensitive without abrogating their IR-mediated G(2)/M checkpoint arrest. ATM phosphorylation is enhanced in CHK1-deficient cells compared with their wild-type counterparts. This correlates with lower nuclear abundance of the PP2A catalytic subunit in CHK1-depleted cells. Stable depletion of CHK1 in an ATM-deficient background showed only a 50% reduction from wild-type CHK1 protein expression levels and resulted in an additive attenuation of the G(2)/M checkpoint response compared with the individual knockdowns. ATM inhibition and 90% CHK1 depletion abrogated the early G(2)/M checkpoint and precluded the cells from mounting an efficient compensatory response to IR at later time points. Our data indicates that dual targeting of ATM and CHK1 functionalities disrupts the compensatory response to DNA damage and could be exploited for developing efficient anti-neoplastic treatments.
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Affiliation(s)
- Stela S Palii
- Environmental Stress and Cancer Group, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC, USA
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