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Xiong H, Hua F, Dong Y, Lin Y, Ying J, Liu J, Wang X, Zhang L, Zhang J. DNA damage response and GATA4 signaling in cellular senescence and aging-related pathology. Front Aging Neurosci 2022; 14:933015. [PMID: 36177479 PMCID: PMC9513149 DOI: 10.3389/fnagi.2022.933015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 08/08/2022] [Indexed: 11/13/2022] Open
Abstract
Aging is the continuous degradation of biological function and structure with time, and cellular senescence lies at its core. DNA damage response (DDR) can activate Ataxia telangiectasia-mutated serine/threonine kinase (ATM) and Rad3-related serine/threonine kinase (ATR), after which p53 activates p21, stopping the cell cycle and inducing cell senescence. GATA4 is a transcription factor that plays an important role in the development of many organs, such as the heart, testis, ovary, foregut, liver, and ventral pancreas. Studies have shown that GATA4 can also contribute to the DDR, leading to aging. Consistently, there is also evidence that the GATA4 signaling pathway is associated with aging-related diseases, including atherosclerosis and heart failure. This paper reviews the relationship between GATA4, DDR, and cellular senescence, as well as its effect on aging-related diseases.
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Affiliation(s)
- Hao Xiong
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Fuzhou Hua
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Yao Dong
- Department of Anesthesiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yue Lin
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Jun Ying
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Jie Liu
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
| | - Xifeng Wang
- Department of Anesthesiology, The First Affiliated Hospital of Nanchang University, Nanchang, China
- Xifeng Wang
| | - Lieliang Zhang
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
- Key Laboratory of Anesthesiology of Jiangxi Province, Nanchang, China
- *Correspondence: Lieliang Zhang
| | - Jing Zhang
- Department of Anesthesiology, The Second Affiliated Hospital of Nanchang University, Nanchang, China
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Schlam-Babayov S, Bensimon A, Harel M, Geiger T, Aebersold R, Ziv Y, Shiloh Y. Phosphoproteomics reveals novel modes of function and inter-relationships among PIKKs in response to genotoxic stress. EMBO J 2020; 40:e104400. [PMID: 33215756 DOI: 10.15252/embj.2020104400] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 08/13/2020] [Accepted: 10/12/2020] [Indexed: 01/10/2023] Open
Abstract
The DNA damage response (DDR) is a complex signaling network that relies on cascades of protein phosphorylation, which are initiated by three protein kinases of the family of PI3-kinase-related protein kinases (PIKKs): ATM, ATR, and DNA-PK. ATM is missing or inactivated in the genome instability syndrome, ataxia-telangiectasia (A-T). The relative shares of these PIKKs in the response to genotoxic stress and the functional relationships among them are central questions in the genome stability field. We conducted a comprehensive phosphoproteomic analysis in human wild-type and A-T cells treated with the double-strand break-inducing chemical, neocarzinostatin, and validated the results with the targeted proteomic technique, selected reaction monitoring. We also matched our results with 34 published screens for DDR factors, creating a valuable resource for identifying strong candidates for novel DDR players. We uncovered fine-tuned dynamics between the PIKKs following genotoxic stress, such as DNA-PK-dependent attenuation of ATM. In A-T cells, partial compensation for ATM absence was provided by ATR and DNA-PK, with distinct roles and kinetics. The results highlight intricate relationships between these PIKKs in the DDR.
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Affiliation(s)
- Sapir Schlam-Babayov
- The David and Inez Myers Laboratory of Cancer Genetics, Department of Human Molecular Genetics and Biochemistry, Tel Aviv University School of Medicine, Tel Aviv, Israel
| | - Ariel Bensimon
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland
| | - Michal Harel
- Department of Human Molecular Genetics and Biochemistry, Tel Aviv University School of Medicine, Tel Aviv, Israel
| | - Tamar Geiger
- Department of Human Molecular Genetics and Biochemistry, Tel Aviv University School of Medicine, Tel Aviv, Israel
| | - Ruedi Aebersold
- Department of Biology, Institute of Molecular Systems Biology, ETH Zurich, Zurich, Switzerland.,Faculty of Science, University of Zurich, Zurich, Switzerland
| | - Yael Ziv
- The David and Inez Myers Laboratory of Cancer Genetics, Department of Human Molecular Genetics and Biochemistry, Tel Aviv University School of Medicine, Tel Aviv, Israel
| | - Yosef Shiloh
- The David and Inez Myers Laboratory of Cancer Genetics, Department of Human Molecular Genetics and Biochemistry, Tel Aviv University School of Medicine, Tel Aviv, Israel
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ATM, DNA-PKcs and ATR: shaping development through the regulation of the DNA damage responses. ACTA ACUST UNITED AC 2019. [DOI: 10.1007/s42764-019-00003-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Induction and inhibition of the pan-nuclear gamma-H2AX response in resting human peripheral blood lymphocytes after X-ray irradiation. Cell Death Discov 2016; 2:16011. [PMID: 27551505 PMCID: PMC4979483 DOI: 10.1038/cddiscovery.2016.11] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 01/17/2016] [Indexed: 01/08/2023] Open
Abstract
Human peripheral blood lymphocytes (HPBLs) are one of the most sensitive cells to ionizing radiation (IR) in the human body, and IR-induced DNA damage and functional impairment of HPBLs are the adverse consequences of IR accidents and major side effects of radiotherapy. Phosphorylated H2AX (γH2AX) is a sensitive marker for DNA double-strand breaks, but the role and regulation of the pan-nuclear γH2AX response in HPBLs after IR remain unclear. We herein demonstrated that the pan-nuclear γH2AX signals were increased in a time- and dose-dependent manner, colocalized with >94% of TUNEL apoptotic staining, and displayed a typical apoptotic pattern in resting HPBLs after low LET X-ray IR. In addition, the X-irradiation-induced pan-nuclear p-ATM and p-DNA-PKcs responses also occurred in resting HPBLs, and were colocalized with 92–95% of TUNEL staining and 97–98% of the pan-nuclear γH2AX signals, respectively, with a maximum at 6 h post irradiation, but disappeared at 24 h post irradiation. Moreover, ATM/DNA-PKcs inhibitor KU55933, p53 inhibitor PFT-μ and pan-caspase inhibitor ZVAD-fmk significantly decreased X-irradiation-induced pan-nuclear γH2AX signals and TUNEL staining, protected HPBLs from apoptosis, but decreased the proliferative response to mitogen in X-irradiated HPBLs. Notably, whereas both KU55933 and PFT-μ increased the IR-induced chromosome breaks and mis-repair events through inhibiting the formation of p-ATM, p-DNA-PKcs and γH2AX foci in X-irradiated HPBLs, the ZVAD-fmk did not increase the IR-induced chromosomal instability. Taken together, our data indicate that pan-nuclear γH2AX response represents an apoptotic signal that is triggered by the transient pan-nuclear ATM and DNA-PKcs activation, and mediated by p53 and pan-caspases in X-irradiated HPBLs, and that caspase inhibitors are better than ATM/DNA-PKcs inhibitors and p53 inhibitors to block pan-nuclear γH2AX response/apoptosis and protect HPBLs from IR.
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Flassig RJ, Maubach G, Täger C, Sundmacher K, Naumann M. Experimental design, validation and computational modeling uncover DNA damage sensing by DNA-PK and ATM. MOLECULAR BIOSYSTEMS 2014; 10:1978-86. [PMID: 24833308 DOI: 10.1039/c4mb00093e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reliable and efficient detection of DNA damage constitutes a vital capability of human cells to maintain genome stability. Following DNA damage, the histone variant H2AX becomes rapidly phosphorylated by the DNA damage response kinases DNA-PKcs and ATM. H2AX phosphorylation plays a central role in signal amplification leading to chromatin remodeling and DNA repair initiation. The contribution of DNA-PKcs and ATM to H2AX phosphorylation is however puzzling. Although ATM is required, DNA-PKcs can substitute for it. Here we analyze the interplay between DNA-PKcs and ATM with a computational model derived by an iterative workflow: switching between experimental design, experiment and model analysis, we generated an extensive set of time-resolved data and identified a conclusive dynamic signaling model out of several alternatives. Our work shows that DNA-PKcs and ATM enforce a biphasic H2AX phosphorylation. DNA-PKcs can be associated to the initial, and ATM to the succeeding phosphorylation phase of H2AX resulting into a signal persistence detection function for reliable damage sensing. Further, our model predictions emphasize that DNA-PKcs inhibition significantly delays H2AX phosphorylation and associated DNA repair initiation.
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Affiliation(s)
- R J Flassig
- Process Systems Engineering Group, Max Planck Institute for Dynamics of Complex Technical Systems, Magdeburg, Germany.
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Martín M, Terradas M, Tusell L, Genescà A. ATM and DNA-PKcs make a complementary couple in DNA double strand break repair. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2012; 751:29-35. [DOI: 10.1016/j.mrrev.2011.12.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 01/21/2023]
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Conceição LEC, Aragão C, Dias J, Costas B, Terova G, Martins C, Tort L. Dietary nitrogen and fish welfare. FISH PHYSIOLOGY AND BIOCHEMISTRY 2012; 38:119-41. [PMID: 22212981 DOI: 10.1007/s10695-011-9592-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Accepted: 12/16/2011] [Indexed: 05/12/2023]
Abstract
Little research has been done in optimizing the nitrogenous fraction of the fish diets in order to minimize welfare problems. The purpose of this review is to give an overview on how amino acid (AA) metabolism may be affected when fish are under stress and the possible effects on fish welfare when sub-optimal dietary nitrogen formulations are used to feed fish. In addition, it intends to evaluate the current possibilities, and future prospects, of using improved dietary nitrogen formulations to help fish coping with predictable stressful periods. Both metabolomic and genomic evidence show that stressful husbandry conditions affect AA metabolism in fish and may bring an increase in the requirement of indispensable AA. Supplementation in arginine and leucine, but also eventually in lysine, methionine, threonine and glutamine, may have an important role in enhancing the innate immune system. Tryptophan, as precursor for serotonin, modulates aggressive behaviour and feed intake in fish. Bioactive peptides may bring important advances in immunocompetence, disease control and other aspects of welfare of cultured fish. Fishmeal replacement may reduce immune competence, and the full nutritional potential of plant-protein ingredients is attained only after the removal or inactivation of some antinutritional factors. This review shows that AA metabolism is affected when fish are under stress, and this together with sub-optimal dietary nitrogen formulations may affect fish welfare. Furthermore, improved dietary nitrogen formulations may help fish coping with predictable stressful events.
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Affiliation(s)
- Luis E C Conceição
- CCMAR-CIMAR L.A., Centro de Ciências do Mar do Algarve, Universidade do Algarve, Campus de Gambelas, 8005-139, Faro, Portugal,
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Gonçalves AP, Máximo V, Lima J, Singh KK, Soares P, Videira A. Involvement of p53 in cell death following cell cycle arrest and mitotic catastrophe induced by rotenone. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:492-9. [PMID: 21223980 DOI: 10.1016/j.bbamcr.2011.01.006] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 12/06/2010] [Accepted: 01/03/2011] [Indexed: 11/17/2022]
Abstract
In order to investigate the cell death-inducing effects of rotenone, a plant extract commonly used as a mitochondrial complex I inhibitor, we studied cancer cell lines with different genetic backgrounds. Rotenone inhibits cell growth through the induction of cell death and cell cycle arrest, associated with the development of mitotic catastrophe. The cell death inducer staurosporine potentiates the inhibition of cell growth by rotenone in a dose-dependent synergistic manner. The tumor suppressor p53 is involved in rotenone-induced cell death, since the drug treatment results in increased expression, phosphorylation and nuclear localization of the protein. The evaluation of the effects of rotenone on a p53-deficient cell line revealed that although not required for the promotion of mitotic catastrophe, functional p53 appears to be essential for the extensive cell death that occurs afterwards. Our results suggest that mitotic slippage also occurs subsequently to the rotenone-induced mitotic arrest and cells treated with the drug for a longer period become senescent. Treatment of mtDNA-depleted cells with rotenone induces cell death and cell cycle arrest as in cells containing wild-type mtDNA, but not formation of reactive oxygen species. This suggests that the effects of rotenone are not dependent from the production of reactive oxygen species. This work highlights the multiple effects of rotenone in cancer cells related to its action as an anti-mitotic drug.
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Affiliation(s)
- António Pedro Gonçalves
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
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Samuelson L, Wright N, Gerber DA. Endodermal progenitor cells isolated from mouse pancreas. ACTA ACUST UNITED AC 2011. [DOI: 10.4236/scd.2011.13005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Tomita M. Involvement of DNA-PK and ATM in radiation- and heat-induced DNA damage recognition and apoptotic cell death. JOURNAL OF RADIATION RESEARCH 2010; 51:493-501. [PMID: 20814172 DOI: 10.1269/jrr.10039] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Exposure to ionizing radiation and hyperthermia results in important biological consequences, e.g. cell death, chromosomal aberrations, mutations, and DNA strand breaks. There is good evidence that the nucleus, specifically cellular DNA, is the principal target for radiation-induced cell lethality. DNA double-strand breaks (DSBs) are considered to be the most serious type of DNA damage induced by ionizing radiation. On the other hand, verifiable mechanisms which can lead to heat-induced cell death are damage to the plasma membrane and/or inactivation of heat-labile proteins caused by protein denaturation and subsequent aggregation. Recently, several reports have suggested that DSBs can be induced after hyperthermia because heat-induced phosphorylated histone H2AX (γ-H2AX) foci formation can be observed in several mammalian cell lines. In mammalian cells, DSBs are repaired primarily through two distinct and complementary mechanisms: non-homologous end joining (NHEJ), and homologous recombination (HR) or homology-directed repair (HDR). DNA-dependent protein kinase (DNA-PK) and ataxia-telangiectasia mutated (ATM) are key players in the initiation of DSB repair and phosphorylate and/or activate many substrates, including themselves. These phosphorylated substrates have important roles in the functioning of cell cycle checkpoints and in cell death, as well as in DSB repair. Apoptotic cell death is a crucial cell suicide mechanism during development and in the defense of homeostasis. If DSBs are unrepaired or misrepaired, apoptosis is a very important system which can protect an organism against carcinogenesis. This paper reviews recently obtained results and current topics concerning the role of DNA-PK and ATM in heat- or radiation-induced apoptotic cell death.
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Affiliation(s)
- Masanori Tomita
- Department of Radiation Oncology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan.
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Liu J, Naegele JR, Lin SL. The DNA-PK catalytic subunit regulates Bax-mediated excitotoxic cell death by Ku70 phosphorylation. Brain Res 2009; 1296:164-75. [PMID: 19664609 DOI: 10.1016/j.brainres.2009.07.101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2009] [Revised: 07/27/2009] [Accepted: 07/30/2009] [Indexed: 10/20/2022]
Abstract
DNA repair deficiency results in neurodegenerative disease and increased susceptibility to excitotoxic cell death, suggesting a critical but undefined role for DNA damage in neurodegeneration. We compared DNA damage, Ku70-Bax interaction, and Bax-dependent excitotoxic cell death in kainic acid-treated primary cortical neurons derived from both wild-type mice and mice deficient in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) encoded by the Prkdc gene. In both wild-type and Prkdc(-/-) neurons, kainic acid treatment resulted in rapid induction of DNA damage (53BP1 foci formation) followed by nuclear pyknosis. Bax deficiency, by either Bax shRNA-mediated knockdown or gene deletion, protected wild-type and heterozygous but not Prkdc(-/-) neurons from kainate-induced excitotoxicity. Cotransfection of DNA-PKcs with Bax shRNA restored Bax shRNA-mediated neuroprotection in Prkdc(-/-) neurons, suggesting that DNA-PKcs is required for kainate-induced activation of the pro-apoptotic Bax pathway. Immunoprecipitation studies revealed that the DNA-PKcs-nonphosphorylatable Ku70 (S6A/S51A) bound 3- to 4-fold greater Bax than wild-type Ku70, suggesting that DNA-PKcs-mediated Ku70 phosphorylation causes release of Bax from Ku70. In support of this, kainic acid induced translocation of a Bax-EGFP fusion protein to the mitochondria in the presence of a cotransfected wild-type, but not mutant Ku70 (S6A/S51A) gene when examined at 4 and 8 h following kainate addition. We conclude that DNA-PKcs links DNA damage to Bax-dependent excitotoxic cell death, by phosphorylating Ku70 on serines 6 and/or 51, to initiate Bax translocation to the mitochondria and directly activate a pro-apoptotic Bax-dependent death cascade.
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Affiliation(s)
- Jia Liu
- Program in Neuroscience and Behavior, Department of Biology, Wesleyan University, Middletown, CT 06459-0170, USA
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Callén E, Jankovic M, Wong N, Zha S, Chen HT, Difilippantonio S, Di Virgilio M, Heidkamp G, Alt FW, Nussenzweig A, Nussenzweig M. Essential role for DNA-PKcs in DNA double-strand break repair and apoptosis in ATM-deficient lymphocytes. Mol Cell 2009; 34:285-97. [PMID: 19450527 DOI: 10.1016/j.molcel.2009.04.025] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Revised: 03/06/2009] [Accepted: 04/24/2009] [Indexed: 02/07/2023]
Abstract
The DNA double-strand break (DSB) repair protein DNA-PKcs and the signal transducer ATM are both activated by DNA breaks and phosphorylate similar substrates in vitro, yet appear to have distinct functions in vivo. Here, we show that ATM and DNA-PKcs have overlapping functions in lymphocytes. Ablation of both kinase activities in cells undergoing immunoglobulin class switch recombination leads to a compound defect in switching and a synergistic increase in chromosomal fragmentation, DNA insertions, and translocations due to aberrant processing of DSBs. These abnormalities are attributed to a compound deficiency in phosphorylation of key proteins required for DNA repair, class switching, and cell death. Notably, both kinases are required for normal levels of p53 phosphorylation in B and T cells and p53-dependent apoptosis. Our experiments reveal a DNA-PKcs-dependent pathway that regulates DNA repair and activation of p53 in the absence of ATM.
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Affiliation(s)
- Elsa Callén
- Experimental Immunology Branch, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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Artemis and nonhomologous end joining-independent influence of DNA-dependent protein kinase catalytic subunit on chromosome stability. Mol Cell Biol 2008; 29:503-14. [PMID: 19015239 DOI: 10.1128/mcb.01354-08] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Deficiency in both ATM and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) is synthetically lethal in developing mouse embryos. Using mice that phenocopy diverse aspects of Atm deficiency, we have analyzed the genetic requirements for embryonic lethality in the absence of functional DNA-PKcs. Similar to the loss of ATM, hypomorphic mutations of Mre11 (Mre11(ATLD1)) led to synthetic lethality when juxtaposed with DNA-PKcs deficiency (Prkdc(scid)). In contrast, the more moderate DNA double-strand break response defects associated with the Nbs1(DeltaB) allele permitted viability of some Nbs1(DeltaB/DeltaB) Prkdc(scid/scid) embryos. Cell cultures from Nbs1(DeltaB/DeltaB) Prkdc(scid/scid) embryos displayed severe defects, including premature senescence, mitotic aberrations, sensitivity to ionizing radiation, altered checkpoint responses, and increased chromosome instability. The known functions of DNA-PKcs in the regulation of Artemis nuclease activity or nonhomologous end joining-mediated repair do not appear to underlie the severe genetic interaction. Our results reveal a role for DNA-PKcs in the maintenance of S/G(2)-phase chromosome stability and in the induction of cell cycle checkpoint responses.
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Chromium-mediated apoptosis: Involvement of DNA-dependent protein kinase (DNA-PK) and differential induction of p53 target genes. DNA Repair (Amst) 2008; 7:1484-99. [DOI: 10.1016/j.dnarep.2008.05.007] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2007] [Revised: 05/02/2008] [Accepted: 05/12/2008] [Indexed: 12/25/2022]
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Long X, Goldenthal MJ, Marín-García J. Oxidative stress enhances phosphorylation of p53 in neonatal rat cardiomyocytes. Mol Cell Biochem 2007; 303:167-74. [PMID: 17457521 DOI: 10.1007/s11010-007-9470-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2006] [Accepted: 03/30/2007] [Indexed: 12/31/2022]
Abstract
p53 is an important regulator of cell growth and apoptosis and its activity is regulated by phosphorylation. Accordingly, in neonatal rat cardiomyocytes we examined the involvement of p53 in H(2)O(2)-induced apoptosis. Treatment with 50-100 microM H(2)O(2) markedly induced apoptosis in cardiomyocytes, as assessed by gel electrophoresis of genomic DNA. To examine whether H(2)O(2) increases p53 phosphorylation in cardiomyocytes, we utilized an antibody that specifically recognizes phosphorylated p53 at serine-15. The level of phosphorylated p53 was markedly increased by 100 microM H(2)O(2) at 30 and 60 min. Using specific protein kinase inhibitors we examined the involvement of protein kinases in p53 phosphorylation in response to H(2)O(2) treatment. However, staurosporine, a broad spectrum inhibitor of protein kinases, SB202190, a specific p38 kinase inhibitor, PD98059, a MAP kinase inhibitor, wortmannin, an inhibitor of DNA-PK and PI3 kinase, SP600125, a JNK inhibitor and caffeine,an inhibitor of ATM and ATR, failed to prevent the H(2)O(2)-induced phosphorylation of p53. cDNA microarray revealed that H(2)O(2) markedly increased expression of several p53 upstream modifiers such as the p300 coactivator protein and several downstream effectors such as gadd45, but decreased the expression of MDM2, a negative regulator of p53. Our results suggest that phosphorylation of p53 at serine-15 may be an important signaling event in the H(2)O(2)-mediated apoptotic process.
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Affiliation(s)
- Xilin Long
- The Molecular Cardiology and Neuromuscular Institute, Highland Park, NJ 08904, USA
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Hatch T, Derijck AAHA, Black PD, van der Heijden GW, de Boer P, Dubrova YE. Maternal effects of the scid mutation on radiation-induced transgenerational instability in mice. Oncogene 2007; 26:4720-4. [PMID: 17237807 DOI: 10.1038/sj.onc.1210253] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The results of a number of recent studies show that mutation rates in the offspring of irradiated parents are substantially elevated, however, the effect of parental genotype on transgenerational instability remains poorly understood. Here, we have analysed the mutation frequency at an expanded simple tandem repeat (ESTR) locus in the germline and bone marrow of the first-generation male offspring of control and irradiated male mice. The frequency of ESTR mutation was studied in the offspring of two reciprocal matings male symbol scid x female symbol BALB/c and male symbol BALB/c x female symbol scid, which were compared with that in BALB/c mice. In the offspring of the BALB/c x BALB/c and male symbol scid x female symbol BALB/c matings, which were conceived after paternal sperm irradiation, the frequency of ESTR mutation was significantly elevated in both tissues. In contrast, ESTR mutation frequency was only slightly elevated in the offspring of male symbol BALB/c x female symbol scid mating conceived after paternal irradiation. The results of this study suggest that the oocytes of scid females are unable to fully support the repair of double-strand breaks induced in paternal sperm which may in turn result in the elimination of cells/embryos containing high levels of DNA damage, thus partially preventing the manifestation of genomic instability.
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Affiliation(s)
- T Hatch
- Department of Genetics, University of Leicester, Leicester, UK
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Matsumoto M, Furihata M, Ohtsuki Y. Posttranslational phosphorylation of mutant p53 protein in tumor development. Med Mol Morphol 2006; 39:79-87. [PMID: 16821145 DOI: 10.1007/s00795-006-0320-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Accepted: 04/20/2006] [Indexed: 01/10/2023]
Abstract
p53 has been called the "cellular gatekeeper" and the "genome guard," because in response to exposure to DNA-damaging agents, it induces cell-cycle arrest in G1 or apoptosis and also directly affects DNA replication. Multiple mechanisms regulate p53 activity and posttranslational modification, including multisite phosphorylation of wild-type p53, in particular. Normal functions of wild-type p53 are abrogated by mutation of this gene, and oncogenic studies have revealed that p53 mutation is among the most common genetic alteration in human cancers. It is generally accepted that mutant p53 protein may not only lose the tumor suppressor functions of wild-type p53 but also acquire additional tumorigenetic roles, including dominant-negative effects and gain of function. Although many studies have revealed such aberrant functions of mutant p53, less is known about the posttranslational phosphorylation status of mutant p53 and novel biological functions of phosphorylation in carcinogenesis.
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Affiliation(s)
- Manabu Matsumoto
- Department of Clinical Laboratory, Kochi Medical School Hospital, Nankoku, Kochi, 783-8305, Japan.
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Abstract
An appropriate response to genotoxic stress is essential for maintenance of genome stability and avoiding the passage to neoplasia. Nuclear factor kappaB (NF-kappaB) is activated as part of the DNA damage response and is thought to orchestrate a cell survival pathway, which, together with the activation of cell cycle checkpoints and DNA repair, allows the cell in cases of limited damage to restore a normal life cycle, unharmed. In this respect, NF-kappaB is one of the main factors accounting for chemotherapy resistance and as such impedes effective cancer treatment, representing an important drug target. Despite this high clinical relevance, signalling cascades leading to DNA damage-induced NF-kappaB activation are poorly understood and the use of highly divergent experimental set-ups in the past led to many controversies in the field. Therefore, in this review, we will try to summarize the current knowledge of distinct DNA damage-induced NF-kappaB signalling pathways.
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Affiliation(s)
- S Janssens
- Department of Biochemistry, University of Lausanne, Chemin des Boveresses 155, Epalinges CH-1066, Switzerland
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19
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Baserga M, Hale MA, Ke X, Wang ZM, Yu X, Callaway CW, McKnight RA, Lane RH. Uteroplacental insufficiency increases p53 phosphorylation without triggering the p53-MDM2 functional circuit response in the IUGR rat kidney. Am J Physiol Regul Integr Comp Physiol 2006; 291:R412-8. [PMID: 16914427 DOI: 10.1152/ajpregu.00880.2005] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Uteroplacental insufficiency (UPI) leads to intrauterine growth restriction (IUGR), which predisposes infants toward renal insufficiency early in life and increases the risk of kidney-related adult morbidities, such as hypertension. This compromised in utero environment has been demonstrated to impair nephrogenesis, as evidenced by a reduced nephron endowment in humans and in rats rendered IUGR by UPI. Concordantly, we have observed that IUGR rats have increased kidney p53 protein levels associated with increased apoptosis. Several factors can regulate p53 gene expression and activity, including posttranslational modifications and protein-protein interactions in the cell. Among these, two important mechanisms are 1) phosphorylation of the amino terminal serine 15 [phospho-p53 (Ser15)], which increases p53 stability and apoptotic activity, and 2) the murine double-minute (MDM2) functional circuit that limits further p53-induced apoptosis by promoting proteosomal degradation of p53. We hypothesize that UPI induces an increase in phospho-p53 (Ser15) in association with an absent MDM2 response, predisposing the kidney to increased apoptosis. To test our hypothesis, we induced IUGR through bilateral uterine artery ligation of the pregnant rat. UPI significantly increased phospho-p53 (Ser15), as well as ataxia teleangiectasia-mutated kinase/A-T-related kinase and dsDNA-activated protein kinase kinase levels, which induce phosphorylation of p53. In contrast, UPI induced no increase in kidney MDM2 mRNA and protein levels in IUGR pups. We conclude that among multiple mechanisms that affect nephrogenesis, UPI induces an increase in p53 phosphorylation without a corresponding increase in MDM2 expression, and we speculate that this response may contribute to the increased apoptosis previously described in the IUGR kidney.
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Affiliation(s)
- Mariana Baserga
- University of Utah School of Medicine, Department of Pediatrics, Division of Neonatology, PO Box 581289, Salt Lake City, UT 84158, USA.
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20
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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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21
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Koike M, Sugasawa J, Koike A, Kohno Y. p53 phosphorylation in mouse skin and in vitro human skin model by high-dose-radiation exposure. JOURNAL OF RADIATION RESEARCH 2005; 46:461-8. [PMID: 16394637 DOI: 10.1269/jrr.46.461] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
The skin is an external organ that is most frequently exposed to radiation. High-dose radiation initiates and promotes acute radiation injury. Thus, it is important to investigate the influence of high-dose radiation exposure on the skin at the molecular level. The post-translational modification of p53 plays a central role in radiation responses, including apoptosis and cell growth arrest. Although it is well known that ataxia telangiectasia mutated (ATM) kinase and DNA-dependent protein kinase (DNA-PK) can phosphorylate Ser15/Ser18 of p53 in vitro, the post-translational modification pattern and the modifier of p53 in the skin after exposure to high-dose X-rays are not yet well understood. Here we show that the phosphorylation of p53 on Ser15/Ser18, as well as the phosphorylation of histone H2AX on Ser139, was detected in the keratinocytes of the mouse skin and human skin models after high-dose X-ray irradiation. Following high-dose X-ray irradiation, both proteins were also phosphorylated in the skin keratinocytes of both ATM gene knockout mice and DNA-PK-deficient SCID mice.
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Affiliation(s)
- Manabu Koike
- Radiation Hazards Research Group, National Institute of Radiological Sciences, Japan.
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22
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Martín M, Genescà A, Latre L, Jaco I, Taccioli GE, Egozcue J, Blasco MA, Iliakis G, Tusell L. Postreplicative Joining of DNA Double-Strand Breaks Causes Genomic Instability in DNA-PKcs–Deficient Mouse Embryonic Fibroblasts. Cancer Res 2005; 65:10223-32. [PMID: 16288010 DOI: 10.1158/0008-5472.can-05-0932] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Combined cytogenetic and biochemical approaches were used to investigate the contributions of the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs) in the maintenance of genomic stability in nonirradiated and irradiated primary mouse embryo fibroblasts (MEF). We show that telomere dysfunction contributes only marginally to genomic instability associated with DNA-PKcs deficiency in the absence of radiation. Following exposure to ionizing radiation, DNA-PKcs-/- MEFs are radiosensitized mainly as a result of the associated DNA double-strand break (DSB) repair defect. This defect manifests as an increase in the fraction of DSB rejoining with slow kinetics although nearly complete rejoining is achieved within 48 hours. Fifty-four hours after ionizing radiation, DNA-PKcs-/- cells present with a high number of simple and complex chromosome rearrangements as well as with unrepaired chromosome breaks. Overall, induction of chromosome aberrations is 6-fold higher in DNA-PKcs-/- MEFs than in their wild-type counterparts. Spectral karyotyping-fluorescence in situ hybridization technology distinguishes between rearrangements formed by prereplicative and postreplicative DSB rejoining and identifies sister chromatid fusion as a significant source of genomic instability and radiation sensitivity in DNA-PKcs-/- MEFs. Because DNA-PKcs-/- MEFs show a strong G1 checkpoint response after ionizing radiation, we propose that the delayed rejoining of DNA DSBs in DNA-PKcs-/- MEFs prolongs the mean life of broken chromosome ends and increases the probability of incorrect joining. The preponderance of sister chromatid fusion as a product of incorrect joining points to a possible defect in S-phase arrest and emphasizes proximity in these misrepair events.
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Affiliation(s)
- Marta Martín
- Department of Cell Biology, Physiology, and Immunology, Institute of Biotechnology and Biomedicine, Universitat Autònoma de Barcelona, Bellaterra, Spain
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23
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Brew CT, Aronchik I, Hsu JC, Sheen JH, Dickson RB, Bjeldanes LF, Firestone GL. Indole-3-carbinol activates the ATM signaling pathway independent of DNA damage to stabilize p53 and induce G1 arrest of human mammary epithelial cells. Int J Cancer 2005; 118:857-68. [PMID: 16152627 DOI: 10.1002/ijc.21445] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The phytochemical indole-3-carbinol (I3C), from cruciferous vegetables such as broccoli, has been shown to elicit a potent anti-proliferative response in human breast cancer cell lines. Treatment of the immortalized human mammary epithelial cell line MCF10A with I3C induced a G1 cell cycle arrest, elevated p53 tumor suppressor protein levels and stimulated expression of downstream transcriptional target, p21. I3C treatment also elevated p53 levels in several breast cancer cell lines that express mutant p53. I3C did not arrest MCF10A cells stably transfected with dominant-negative p53, establishing a functional requirement for p53. Cell fractionation and immunolocalization studies revealed a large fraction of stabilized p53 protein in the nucleus of I3C-treated MCF10A cells. With I3C treatment, phosphatidyl-inositol-3-kinase family member ataxia telangiectasia-mutated (ATM) was phosphorylated, as were its substrates p53, CHK2 and BRCA1. Phosphorylation of p53 at the N-terminus has previously been shown to disrupt the interaction between p53 and its ubiquitin ligase, MDM2, and therefore stabilizing p53. Coimmunoprecipitation analysis revealed that I3C reduced by 4-fold the level of MDM2 protein that associated with p53. The p53-MDM2 interaction and absence of p21 production were restored in cells treated with I3C and the ATM inhibitor wortmannin. Significantly, I3C does not increase the number of 53BP1 foci or H2AX phosphorylation, indicating that ATM is activated independent of DNA double-strand breaks. Taken together, our results demonstrate that I3C activates ATM signaling through a novel pathway to stimulate p53 phosphorylation and disruption of the p53-MDM2 interaction, which releases p53 to induce the p21 CDK inhibitor and a G1 cell cycle arrest.
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Affiliation(s)
- Christine T Brew
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, University of California at Berkeley, Berkeley, CA 94720-3200, USA
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24
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Ban S, Michikawa Y, Ishikawa KI, Sagara M, Watanabe K, Shimada Y, Inazawa J, Imai T. Radiation sensitivities of 31 human oesophageal squamous cell carcinoma cell lines. Int J Exp Pathol 2005; 86:231-40. [PMID: 16045545 PMCID: PMC2517430 DOI: 10.1111/j.0959-9673.2005.00431.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2005] [Accepted: 03/17/2005] [Indexed: 11/29/2022] Open
Abstract
The purpose of this study was to determine the radiosensitivities of 31 human oesophageal squamous cell carcinoma cell lines with a colony-formation assay. A large variation in radiosensitivity existed among 31 cell lines. Such a large variation may partly explain the poor result of radiotherapy for this cancer. One cell line (KYSE190) demonstrated an unusual radiosensitivity. Ataxia-telangiectasia-mutated (ATM) gene in these cells had five missense mutations, and ATM protein was truncated or degraded. Inability to phosphorylate Chk2 in the irradiated KYSE190 cells suggests that the ATM protein in these cells had lost its function. The dysfunctional ATM protein may be a main cause of unusual radiosensitivity of KYSE190 cells. Because the donor of these cells was not diagnosed with ataxia telangiectasia, mutations in ATM gene might have occurred during the initiation and progression of cancer. Radiosensitive cancer developed in non-hereditary diseased patients must be a good target for radiotherapy.
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Affiliation(s)
- Sadayuki Ban
- Frontier Research Center, National Institute of Radiological Sciences, Anagawa, Inage-ku, Chiba 263-8555, Japan.
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25
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Subramanian D, Griffith JD. Modulation of p53 binding to Holliday junctions and 3-cytosine bulges by phosphorylation events. Biochemistry 2005; 44:2536-44. [PMID: 15709766 DOI: 10.1021/bi048700u] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Recognition of certain types of DNA lesions by the tumor suppressor protein, p53, represents one of the several downstream functions of this protein in response to DNA damage. This binding property is regulated by several factors including posttranslational modifications and interactions with other proteins. Phosphorylation by several stress-response kinases activates p53 by increasing protein stability as well as transactivation properties. Here we examined the effect of phosphorylation events on the sequence-independent binding properties of p53 using two DNA substrates: One resembling Holliday junctions and the other containing extra base bulges. Gel retardation assays showed that dephosphorylation of serine 392 in the C-terminal domain of p53 greatly reduces Holliday junction and lesion recognition. In contrast, sequence-specific binding is disrupted by the removal of some N-terminal phosphates but not serine 392. Rephosphorylation of p53 by certain kinases can restore p53 recognition of Holliday junctions and 3-cytosine bulges. In all cases, phosphorylation of serine 392 occurs; however, reactivation also involves other residues. Together, the results show that p53 DNA binding activity is strongly regulated by the phosphorylation state of the protein.
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Affiliation(s)
- Deepa Subramanian
- Lineberger Comprehensive Cancer Center and Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7295, USA
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26
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Peng Y, Woods RG, Beamish H, Ye R, Lees-Miller SP, Lavin MF, Bedford JS. Deficiency in the catalytic subunit of DNA-dependent protein kinase causes down-regulation of ATM. Cancer Res 2005; 65:1670-7. [PMID: 15753361 DOI: 10.1158/0008-5472.can-04-3451] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Previous reports have suggested a connection between reduced levels of the catalytic subunit of DNA-dependent protein kinases (DNA-PKcs), a component of the nonhomologous DNA double-strand breaks end-joining system, and a reduction in ATM. We studied this possible connection in other DNA-PKcs-deficient cell types, and following knockdown of DNA-PKcs with small interfering RNA, Chinese hamster ovary V3 cells, lacking DNA-PKcs, had reduced levels of ATM and hSMG-1, but both were restored after transfection with PRKDC. Atm levels were also reduced in murine scid cells. Reduction of ATM in a human glioma cell line lacking DNA-PKcs was accompanied by defective signaling through downstream substrates, post-irradiation. A large reduction of DNA-PKcs was achieved in normal human fibroblasts after transfection with two DNA-PKcs small interfering RNA sequences. This was accompanied by a reduction in ATM. These data were confirmed using immunocytochemical detection of the proteins. Within hours after transfection, a decline in PRKDC mRNA was seen, followed by a more gradual decline in DNA-PKcs protein beginning 1 day after transfection. No change in ATM mRNA was observed for 2 days post-transfection. Only after the DNA-PKcs reduction occurred was a reduction in ATM mRNA observed, beginning 2 days post-transfection. The amount of ATM began to decline, starting about 3 days post-treatment, then it declined to levels comparable to DNA-PKcs. Both proteins returned to normal levels at later times. These data illustrate a potentially important cross-regulation between the nonhomologous end-joining system for rejoining of DNA double-strand breaks and the ATM-dependent damage response network of pathways, both of which operate to maintain the integrity of the genome.
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Affiliation(s)
- Yuanlin Peng
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, Colorado 80523, USA
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27
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Yamaguchi S, Hasegawa M, Aizawa S, Tanaka K, Yoshida K, Noda Y, Tatsumi K, Hirokawa K, Kitagawa M. DNA-dependent protein kinase enhances DNA damage-induced apoptosis in association with Friend gp70. Leuk Res 2005; 29:307-16. [PMID: 15661267 DOI: 10.1016/j.leukres.2004.07.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2004] [Accepted: 07/24/2004] [Indexed: 01/01/2023]
Abstract
Friend leukemia virus (FLV) infection strongly enhances gamma-irradiation-induced apoptosis of hematopoietic cells of C3H hosts leading to a lethal anemia. Experiments using p53 knockout mice with the C3H background have clarified that the apoptosis is p53-dependent and would not be associated with changes of cell populations caused by the infection with FLV. In bone marrow cells of FLV + total body irradiation (TBI)-treated C3H mice, the p53 protein was prominently activated to overexpress p21 and bax suggesting that apoptosis-enhancing mechanisms lay upstream of p53 protein in the signaling pathway. Neither of DNA-dependent protein kinase (DNA-PK)-deficient SCID mice nor ataxia telangiectasia mutated (ATM) gene knockout mice with the C3H background exhibited a remarkable enhancement of apoptosis or p53 activation on FLV + TBI-treatment indicating that DNA-PK and ATM were both essential. ATM appeared necessary for introducing DNA damage-induced apoptosis, while DNA-PK enhanced p53-dependent apoptosis under FLV-infection. Surprisingly, viral envelope protein, gp70, was co-precipitated with DNA-PK but not with ATM in FLV + TBI-treated C3H mice. These results indicated that FLV-infection enhances DNA damage-induced apoptosis via p53 activation and that DNA-PK, in association with gp70, might play critical roles in modulating the signaling pathway.
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Affiliation(s)
- Shuichi Yamaguchi
- Department of Comprehensive Pathology, Aging and Developmental Sciences, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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28
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Sengupta S, Harris CC. p53: traffic cop at the crossroads of DNA repair and recombination. Nat Rev Mol Cell Biol 2005; 6:44-55. [PMID: 15688066 DOI: 10.1038/nrm1546] [Citation(s) in RCA: 408] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
p53 mutants that lack DNA-binding activities, and therefore, transcriptional activities, are among the most common mutations in human cancer. Recently, a new role for p53 has come to light, as the tumour suppressor also functions in DNA repair and recombination. In cooperation with its function in transcription, the transcription-independent roles of p53 contribute to the control and efficiency of DNA repair and recombination.
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Affiliation(s)
- Sagar Sengupta
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, 37 Convent Drive, Building 37, Room 3068, Bethesda, Maryland, 20892-4255, USA
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29
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Abstract
Chk2 is a critical mediator of diverse cellular responses to DNA damage. Activation of Chk2 by DNA damage requires phosphorylation at sites including Thr68. In earlier work, we found that an activity present in rabbit reticulocyte lysates phosphorylates and activates Chk2. We now find that hypophosphorylated Chk2 can be phosphorylated at Thr68 by various subcellular fractions of HEK293 cells. This activity is sensitive to the phosphatidylinositol 3'-kinase-like kinase inhibitor wortmannin, but not to caffeine. DNA enhances the Chk2 phosphorylation by cellular fractions in vitro. The wortmannin-sensitive Chk2 kinase activity is present in fractions from ATM-deficient cells. In contrast, Chk2 was not efficiently phosphorylated at Thr68 in vitro by fractions from cells with a defective DNA-dependent protein kinase (DNA-PK) catalytic subunit. Chk2 is phosphorylated by purified DNA-PK in vitro. Endogenous Chk2 coimmunoprecipitates Ku70 and Ku80. In a series of matched cell lines having and lacking functional DNA-PK, Chk2 activation by exposure of cells to ionizing radiation, or to camptothecin was consistently diminished in the absence of DNA-PK. Down-regulation of DNA-PK(cs) by either siRNA or a chemical inhibitor attenuated radiation-induced Chk2 phosphorylation. Ionizing radiation-induced Chk2 phosphorylation was wortmannin-sensitive in ATM-defective cells with depleted ATR. These results suggest that DNA-PK augments ATM and ATR in activation of Chk2 by DNA damage.
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Affiliation(s)
- Jia Li
- Department of Pathology, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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30
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Komiyama S, Taniguchi S, Matsumoto Y, Tsunoda E, Ohto T, Suzuki Y, Yin HL, Tomita M, Enomoto A, Morita A, Suzuki T, Ohtomo K, Hosoi Y, Suzuki N. Potentiality of DNA-dependent protein kinase to phosphorylate Ser46 of human p53. Biochem Biophys Res Commun 2004; 323:816-22. [PMID: 15381073 DOI: 10.1016/j.bbrc.2004.08.161] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2004] [Indexed: 01/12/2023]
Abstract
DNA damage induces accumulation and activation of p53 via various posttranslational modifications. Among them, several lines of evidence indicated the phosphorylation of Ser46 as an important mediator of DNA damage-induced apoptosis but the responsible kinase remains to be clarified, especially in the case of ionizing radiation (IR). Here we showed that DNA-dependent protein kinase (DNA-PK) could phosphorylate Ser46 of p53 in addition to reported phosphorylation sites Ser15 and Ser37. However, IR-induced phosphorylation of Ser46 was seen even in M059J, a human glioma cell line lacking DNA-PKcs, and it was, at most, only slightly less than in control M059K. On the other hand, a related kinase ataxia-telangiectasia mutated (ATM), which was shown to be essential for IR-induced phosphorylation of Ser46, could poorly phosphorylate Ser46 by itself. These results collectively suggested two pathways for IR-induced phosphorylation of Ser46, i.e., direct phosphorylation by DNA-PK and indirect phosphorylation via ATM.
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Affiliation(s)
- Shingo Komiyama
- Department of Radiation Oncology, Graduate School of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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31
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Barber RC, Miccoli L, van Buul PPW, Burr KLA, van Duyn-Goedhart A, Angulo JF, Dubrova YE. Germline mutation rates at tandem repeat loci in DNA-repair deficient mice. Mutat Res 2004; 554:287-95. [PMID: 15450426 DOI: 10.1016/j.mrfmmm.2004.05.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2003] [Revised: 05/06/2004] [Accepted: 05/12/2004] [Indexed: 04/30/2023]
Abstract
Mutation rates at two expanded simple tandem repeat (ESTR) loci were studied in the germline of non-exposed and irradiated severe combined immunodeficient (scid) and poly(ADP-ribose) polymerase (PARP-1-/-) deficient male mice. Non-exposed scid and PARP-/- male mice showed considerably elevated ESTR mutation rates, far higher than those in wild-type isogenic mice and other inbred strains. The irradiated scid and PARP-1-/- male mice did not show any detectable increases in their mutation rate, whereas significant ESTR mutation induction was observed in the irradiated wild-type isogenic males. ESTR mutation spectra in the scid and PARP-1-/- strains did not differ from those in the isogenic wild-type strains. Considering these data and the results of previous studies, we propose that a delay in repair of DNA damage in scid and PARP-1-/- mice could result in replication fork pausing which, in turn, may affect ESTR mutation rate in the non-irradiated males. The lack of mutation induction in irradiated scid and PARP-1-/- can be explained by the high cell killing effects of irradiation on the germline of deficient mice.
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Affiliation(s)
- Ruth C Barber
- Department of Genetics, University of Leicester, LE1 7RH, UK
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32
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Abstract
The DNA-dependent protein kinase (DNA-PK) plays a critical role in DNA double-strand break (DSB) repair and in V(D)J recombination. DNA-PK also plays a very important role in triggering apoptosis in response to severe DNA damage or critically shortened telomeres. Paradoxically, components of the DNA-PK complex are present at the mammalian telomere where they function in capping chromosome ends to prevent them from being mistaken for double-strand breaks. In addition, DNA-PK appears to be involved in mounting an innate immune response to bacterial DNA and to viral infection. As DNA-PK localizes very rapidly to DNA breaks and phosphorylates itself and other damage-responsive proteins, it appears that DNA-PK serves as both a sensor and a transducer of DNA-damage signals. The many roles of DNA-PK in the mammalian cell are discussed in this review with particular emphasis on recent advances in our understanding of the phosphorylation events that take place during the activation of DNA-PK at DNA breaks.
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Affiliation(s)
- Sandeep Burma
- Life Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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33
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Stiff T, O'Driscoll M, Rief N, Iwabuchi K, Löbrich M, Jeggo PA. ATM and DNA-PK function redundantly to phosphorylate H2AX after exposure to ionizing radiation. Cancer Res 2004; 64:2390-6. [PMID: 15059890 DOI: 10.1158/0008-5472.can-03-3207] [Citation(s) in RCA: 758] [Impact Index Per Article: 37.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
H2AX phosphorylation is an early step in the response to DNA damage. It is widely accepted that ATM (ataxia telangiectasia mutated protein) phosphorylates H2AX in response to DNA double-strand breaks (DSBs). Whether DNA-dependent protein kinase (DNA-PK) plays any role in this response is unclear. Here, we show that H2AX phosphorylation after exposure to ionizing radiation (IR) occurs to similar extents in human fibroblasts and in mouse embryo fibroblasts lacking either DNA-PK or ATM but is ablated in ATM-deficient cells treated with LY294002, a drug that specifically inhibits DNA-PK. Additionally, we show that inactivation of both DNA-PK and ATM is required to ablate IR-induced H2AX phosphorylation in chicken cells. We confirm that H2AX phosphorylation induced by DSBs in nonreplicating cells is ATR (ataxia telangiectasia and Rad3-related protein) independent. Taken together, we conclude that under most normal growth conditions, IR-induced H2AX phosphorylation can be carried out by ATM and DNA-PK in a redundant, overlapping manner. In contrast, DNA-PK cannot phosphorylate other proteins involved in the checkpoint response, including chromatin-associated Rad17. However, by phosphorylating H2AX, DNA-PK can contribute to the presence of the damage response proteins MDC1 and 53BP1 at the site of the DSB.
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Affiliation(s)
- Tom Stiff
- Genome Damage and Stability Centre, University of Sussex, East Sussex, United Kingdom
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34
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Kühne C, Tjörnhammar ML, Pongor S, Banks L, Simoncsits A. Repair of a minimal DNA double-strand break by NHEJ requires DNA-PKcs and is controlled by the ATM/ATR checkpoint. Nucleic Acids Res 2004; 31:7227-37. [PMID: 14654698 PMCID: PMC291875 DOI: 10.1093/nar/gkg937] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Mammalian cells primarily rejoin DNA double-strand breaks (DSBs) by the non-homologous end-joining (NHEJ) pathway. The joining of the broken DNA ends appears directly without template and accuracy is ensured by the NHEJ factors that are under ATM/ATR regulated checkpoint control. In the current study we report the engineering of a mono-specific DNA damaging agent. This was used to study the molecular requirements for the repair of the least complex DSB in vivo. Single-chain PvuII restriction enzymes fused to protein delivery sequences transduce cells efficiently and induce blunt end DSBs in vivo. We demonstrate that beside XRCC4/LigaseIV and KU, the DNA-PK catalytic subunit (DNA-PKcs) is also essential for the joining of this low complex DSB in vivo. The appearance of blunt end 3'-hydroxyl and 5'-phosphate DNA DSBs induces a significantly higher frequency of anaphase bridges in cells that do not contain functional DNA-PKcs, suggesting an absolute requirement for DNA-PKcs in the control of chromosomal stability during end joining. Moreover, these minimal blunt end DSBs are sufficient to induce a p53 and ATM/ATR checkpoint function.
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Affiliation(s)
- Christian Kühne
- International Center for Genetic Engineering and Biotechnology (ICGEB), Area Science Park, Padriciano 99, I-34000 Trieste, Italy.
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35
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Tomita M, Suzuki N, Matsumoto Y, Enomoto A, Yin HL, Hosoi Y, Hirano K, Sakai K. Wortmannin-enhanced X-ray-induced apoptosis of human T-cell leukemia MOLT-4 cells possibly through the JNK/SAPK pathway. Radiat Res 2003; 160:467-77. [PMID: 12968928 DOI: 10.1667/rr3055] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
We demonstrated that enhancement of X-ray-induced apoptosis/rapid cell death by wortmannin accompanied by increased activation of JNK/SAPK in human leukemia MOLT-4 cells. Rapid cell death/apoptosis was determined either by the dye exclusion test or by the appearance of Annexin V-positive cells and cleaved PARP fragments. Enhancement was observed only at higher concentrations of wortmannin, i.e. 1 microM or more. At these high concentrations, both DNA-PK and ATM were inhibited. X-ray-induced phosphorylation of Ser 15 of p53/TP53, accumulation of both p53/TP53 and p21/WAF1/CDKN1A, and phosphorylation of XRCC4 were all suppressed. The enhancement of apoptosis/rapid cell death by wortmannin was prevented by addition of caspase inhibitors, Z-VAD-FMK or Ac-DEVD-CHO, or by transfection and overexpression of mouse Bcl2, which is known as an anti-apoptosis protein. The requirement for a high concentration of wortmannin, i.e. 1 microM or more, indicates that inhibition of both DNA-PK and ATM was necessary for the enhanced apoptosis/rapid cell death. Phosphorylation of AKT/PKB was completely suppressed at a much lower concentration, i.e. 0.1 microM wortmannin, where no enhancement of X-ray-induced apoptosis/rapid cell death was observed. On the other hand, X-ray-induced phosphorylation of JNK and its kinase activity as well as apoptosis/rapid cell death were all significantly enhanced only at high concentrations of wortmannin, i.e. 1 microM or more. Furthermore, the extent of enhancement of both JNK phosphorylation and of apoptosis/rapid cell death by wortmannin was less in Rh1a cells, which are ceramide- and radiation-resistant variant cells compared to the parental MOLT-4 cells. Therefore, activation of the JNK pathway was considered important for the enhancement of X-ray-induced apoptosis/rapid cell death of MOLT-4 cells by wortmannin, because of the requirement for a higher concentration of wortmannin than that required for inhibition of AKT phosphorylation. The suppression of the AKT-dependent pathway by wortmannin may have some underlying role in activating the JNK pathway toward the enhancement of cell death in the current system.
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Affiliation(s)
- Masanori Tomita
- Department of Radiation Oncology, Graduate School of Medicine, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan
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Criswell T, Leskov K, Miyamoto S, Luo G, Boothman DA. Transcription factors activated in mammalian cells after clinically relevant doses of ionizing radiation. Oncogene 2003; 22:5813-27. [PMID: 12947388 DOI: 10.1038/sj.onc.1206680] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Over the past 15 years, a wealth of information has been published on transcripts and proteins 'induced' (requiring new protein synthesis) in mammalian cells after ionizing radiation (IR) exposure. Many of these studies have also attempted to elucidate the transcription factors that are 'activated' (i.e., not requiring de novo synthesis) in specific cells by IR. Unfortunately, all too often this information has been obtained using supralethal doses of IR, with investigators assuming that induction of these proteins, or activation of corresponding transcription factors, can be 'extrapolated' to low-dose IR exposures. This review focuses on what is known at the molecular level about transcription factors induced at clinically relevant (< or =2 Gy) doses of IR. A review of the literature demonstrates that extrapolation from high doses of IR to low doses of IR is inaccurate for most transcription factors and most IR-inducible transcripts/proteins, and that induction of transactivating proteins at low doses must be empirically derived. The signal transduction pathways stimulated after high versus low doses of IR, which act to transactivate certain transcription factors in the cell, will be discussed. To date, only three transcription factors appear to be responsive (i.e. activated) after physiological doses (doses wherein cells survive or recover) of IR. These are p53, nuclear factor kappa B(NF-kappaB), and the SP1-related retinoblastoma control proteins (RCPs). Clearly, more information on transcription factors and proteins induced in mammalian cells at clinically or environmentally relevant doses of IR is needed to understand the role of these stress responses in cancer susceptibility/resistance and radio-sensitivity/resistance mechanisms.
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Affiliation(s)
- Tracy Criswell
- Department of Radiation Oncology and Program in Molecular Basis of Disease, Laboratory of Molecular Stress Responses, Ireland Comprehensive Cancer Center, Case Western Reserve University and University Hospitals of Cleveland, OH 44106-4942, USA
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Abstract
The double-strand break (DSB) is believed to be one of the most severe types of DNA damage, and if left unrepaired is lethal to the cell. Several different types of repair act on the DSB. The most important in mammalian cells are nonhomologous end-joining (NHEJ) and homologous recombination repair (HRR). NHEJ is the predominant type of DSB repair in mammalian cells, as opposed to lower eucaryotes, but HRR has recently been implicated in critical cell signaling and regulatory functions that are essential for cell viability. Whereas NHEJ repair appears constitutive, HRR is regulated by the cell cycle and inducible signal transduction pathways. More is known about the molecular details of NHEJ than HRR in mammalian cells. This review focuses on the mechanisms and regulation of DSB repair in mammalian cells, the signaling pathways that regulate these processes and the potential crosstalk between NHEJ and HRR, and between repair and other stress-induced pathways with emphasis on the regulatory circuitry associated with the ataxia telangiectasia mutated (ATM) protein.
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Affiliation(s)
- Kristoffer Valerie
- Department of Radiation Oncology, Medical College of Virginia Commonwealth University, Richmond, VA 23298-0058, USA.
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Goudelock DM, Jiang K, Pereira E, Russell B, Sanchez Y. Regulatory interactions between the checkpoint kinase Chk1 and the proteins of the DNA-dependent protein kinase complex. J Biol Chem 2003; 278:29940-7. [PMID: 12756247 DOI: 10.1074/jbc.m301765200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Checkpoints are biochemical pathways that provide cells a mechanism to detect DNA damage and respond by arresting the cell cycle to allow DNA repair. The conserved checkpoint kinase, Chk1, regulates mitotic progression in response to DNA damage by blocking the activation of Cdk1/cyclin B. In this study, we investigate the regulatory interaction between Chk1 and members of the Atm family of kinases and the functional role of the C-terminal non-catalytic domains of Chk1. Chk1 stimulates the kinase activity of DNA-PK (protein kinase) complexes, which leads to increased phosphorylation of p53 on Ser-15 and Ser-37. In addition, Chk1 stimulates DNA-PK-dependent end-joining reactions in vitro. We also show that Chk1 protein complexes bind to single-stranded DNA and DNA ends. These results indicate a connection between components that regulate the checkpoint pathways and DNA-PK complex proteins, which have a role in the repair of double strand breaks.
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Affiliation(s)
- Dawn Marie Goudelock
- Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267-0524, USA
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Kaji A, Zhang Y, Nomura M, Bode AM, Ma WY, She QB, Dong Z. Pifithrin-alpha promotes p53-mediated apoptosis in JB6 cells. Mol Carcinog 2003; 37:138-48. [PMID: 12884365 DOI: 10.1002/mc.10130] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Recently, blockage of p53-dependent transcriptional activation and apoptosis by pifithrin-alpha (PFTalpha) has been reported to be useful for reducing the side effects of cancer therapy and the compound is thus thought to be a specific inhibitor of p53 [Komarov et al., Science 1999;285:1733-1737]. Here, we found that PFTalpha did not inhibit UVB- or doxorubicin (Dox)-stimulated p53-mediated transcriptional activation and apoptosis in JB6 cells. Instead, p53-dependent activation and apoptosis were not only induced by PFTalpha itself but were also enhanced by a combination of PFTalpha with UVB or Dox. Furthermore, PFTalpha-induced apoptosis was mediated through p53-dependent and -independent signaling pathways. Extracellular signal-regulated kinases and p38 kinase, but not c-jun N-terminal kinases (JNKs), were activated, and these activations were required for phosphorylation and accumulation of p53 in the cellular apoptotic response to PFTalpha. Thus, we conclude that PFTalpha is not a specific p53 inhibitor in JB6 cells but is a potential activator of p53-mediated signaling and apoptosis.
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Affiliation(s)
- Akira Kaji
- Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
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Gottifredi V, Shieh SY, Prives C. Regulation of p53 after different forms of stress and at different cell cycle stages. COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY 2003; 65:483-8. [PMID: 12760065 DOI: 10.1101/sqb.2000.65.483] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- V Gottifredi
- Department of Biological Sciences, Columbia University, New York, New York 100279, USA
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41
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Ding H, Duan W, Zhu WG, Ju R, Srinivasan K, Otterson GA, Villalona-Calero MA. P21 response to DNA damage induced by genistein and etoposide in human lung cancer cells. Biochem Biophys Res Commun 2003; 305:950-6. [PMID: 12767922 DOI: 10.1016/s0006-291x(03)00873-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The p21(WAF1/Cip1) gene plays a central role in cell cycle regulation. Here we show that topoisomerase II inhibitors, genistein and etoposide, induce p21(WAF1/Cip1) expression mainly in a p53-dependent manner in human lung cancer cell line A549. However, although p53 accumulated, p21(WAF1/Cip1) expression did not depend on the level of Ser15 phosphorylation of p53. Caffeine, an ataxia telangiectasia-mutated (ATM), and ATM- and Rad3-related kinase (ATR) inhibitor, abrogated genistein-induced p21(WAF1/Cip1) and largely blocked etoposide-induced p21(WAF1/Cip1) expression. Wortmannin, an ATM- and DNA-dependent protein kinase inhibitor, partially inhibited p21(WAF1/Cip1) expression induced by genistein and etoposide, whereas UCN-01, a Chk1 inhibitor, partially blocked etoposide, but not genistein-induced p21(WAF1/Cip1) expression. These data suggest that both genistein and etoposide induce p21(WAF1/Cip1) expression in a p53-dependent manner. Genistein appears to stimulate p21(WAF1/Cip1) expression through p53 via ATM, whereas etoposide may activate both ATM and ATR pathways. Our results suggest different mechanisms participate in genistein and etoposide induced p21(WAF1/Cip1) expression.
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Affiliation(s)
- Haiming Ding
- Arthur James Cancer Hospital and Richard Solove Research Institute, Comprehensive Cancer Center, and Department of Internal Medicine, The Ohio State University, Columbus, OH 43210-1240, USA
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42
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Schedlich LJ, Nilsen T, John AP, Jans DA, Baxter RC. Phosphorylation of insulin-like growth factor binding protein-3 by deoxyribonucleic acid-dependent protein kinase reduces ligand binding and enhances nuclear accumulation. Endocrinology 2003; 144:1984-93. [PMID: 12697706 DOI: 10.1210/en.2002-220798] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The IGF binding proteins (IGFBPs) regulate the mitogenic effects of IGFs in the extracellular environment. Several members of this family, including IGFBP-3, also appear to have IGF-independent effects on cell function. For IGFBP-3 and IGFBP-5, both of which are translocated to the cell nuclei, these effects may be related to their putative nuclear actions. Because reversible phosphorylation is an important mechanism for controlling nuclear protein import, we have examined the effect of phosphorylating IGFBP-3 with a number of serine/threonine protein kinases on its nuclear import. Phosphorylation of IGFBP-3 by the double-stranded DNA-dependent protein kinase (DNA-PK) increased both the nuclear import of IGFBP-3 and the binding of IGFBP-3 to components within the nucleus compared with nonphosphorylated IGFBP-3. However, there was no difference in the binding of the nuclear transport factor, importin beta, to nonphosphorylated and phosphorylated IGFBP-3. The ability of the DNA-PK phosphoform of IGFBP-3 to bind IGFs was severely attenuated, and in contrast to nonphosphorylated IGFBP-3, the DNA-PK phosphoform was unable to transport IGF-I to the nucleus. Furthermore, IGFBP-3 was phosphorylated by DNA-PK when complexed to IGF-I causing the phosphoform to release IGF-I. Together, these results suggest that when IGF-I is cotransported into the nucleus by IGFBP-3, phosphorylation of IGFBP-3 by nuclear DNA-PK provides a means for releasing bound IGF-I and creating a phosphoform of IGFBP-3 with increased affinity for nuclear components.
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Affiliation(s)
- Lynette J Schedlich
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, Sydney, New South Wales 2065, Australia.
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43
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Hamer G, Roepers-Gajadien HL, van Duyn-Goedhart A, Gademan IS, Kal HB, van Buul PPW, Ashley T, de Rooij DG. Function of DNA-protein kinase catalytic subunit during the early meiotic prophase without Ku70 and Ku86. Biol Reprod 2003; 68:717-21. [PMID: 12604618 DOI: 10.1095/biolreprod.102.008920] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
All components of the double-stranded DNA break (DSB) repair complex DNA-dependent protein kinase (DNA-PK), including Ku70, Ku86, and DNA-PK catalytic subunit (DNA-PKcs), were found in the radiosensitive spermatogonia. Although p53 induction was unaffected, spermatogonial apoptosis occurred faster in the irradiated DNA-PKcs-deficient scid testis. This finding suggests that spermatogonial DNA-PK functions in DNA damage repair rather than p53 induction. Despite the fact that early spermatocytes lack the Ku proteins, spontaneous apoptosis of these cells occurred in the scid testis. The majority of these apoptotic spermatocytes were found at stage IV of the cycle of the seminiferous epithelium where a meiotic checkpoint has been suggested to exist. Meiotic synapsis and recombination during the early meiotic prophase induce DSBs, which are apparently less accurately repaired in scid spermatocytes that then fail to pass the meiotic checkpoint. The role for DNA-PKcs during the meiotic prophase differs from that in mitotic cells; it is not influenced by ionizing radiation and is independent of the Ku heterodimer.
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Affiliation(s)
- Geert Hamer
- Department of Endocrinology, Faculty of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands.
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44
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Abstract
Telomerase activity is necessary to maintain the integrity of telomeres, which in turn prevent chromosome ends from being processed and signaled as damaged DNA. That cancer cells rely on telomerase to maintain functional telomeres and to divide indefinitely has highlighted the potential for developing novel therapeutic approaches that target telomerase.
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Affiliation(s)
- María A Blasco
- Department of Immunology and Oncology, National Centre of Biotechnology, Madrid, Spain.
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45
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Hamer G, Roepers-Gajadien HL, van Duyn-Goedhart A, Gademan IS, Kal HB, van Buul PPW, de Rooij DG. DNA double-strand breaks and gamma-H2AX signaling in the testis. Biol Reprod 2003; 68:628-34. [PMID: 12533428 DOI: 10.1095/biolreprod.102.008672] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Within minutes of the induction of DNA double-strand breaks in somatic cells, histone H2AX becomes phosphorylated at serine 139 and forms gamma-H2AX foci at the sites of damage. These foci then play a role in recruiting DNA repair and damage-response factors and changing chromatin structure to accurately repair the damaged DNA. These gamma-H2AX foci appear in response to irradiation and genotoxic stress and during V(D)J recombination and meiotic recombination. Independent of irradiation, gamma-H2AX occurs in all intermediate and B spermatogonia and in preleptotene to zygotene spermatocytes. Type A spermatogonia and round spermatids do not exhibit gamma-H2AX foci but show homogeneous nuclear gamma-H2AX staining, whereas in pachytene spermatocytes gamma-H2AX is only present in the sex vesicle. In response to ionizing radiation, gamma-H2AX foci are generated in spermatogonia, spermatocytes, and round spermatids. In irradiated spermatogonia, gamma-H2AX interacts with p53, which induces spermatogonial apoptosis. These events are independent of the DNA-dependent protein kinase (DNA-PK). Irradiation-independent nuclear gamma-H2AX staining in leptotene spermatocytes demonstrates a function for gamma-H2AX during meiosis. gamma-H2AX staining in intermediate and B spermatogonia, preleptotene spermatocytes, and sex vesicles and round spermatids, however, indicates that the function of H2AX phosphorylation during spermatogenesis is not restricted to the formation of gamma-H2AX foci at DNA double-strand breaks.
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Affiliation(s)
- Geert Hamer
- Department of Endocrinology, Faculty of Biology, Utrecht University, 3584 CH Utrecht, The Netherlands.
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Mauser A, Saito S, Appella E, Anderson CW, Seaman WT, Kenney S. The Epstein-Barr virus immediate-early protein BZLF1 regulates p53 function through multiple mechanisms. J Virol 2002; 76:12503-12. [PMID: 12438576 PMCID: PMC136659 DOI: 10.1128/jvi.76.24.12503-12512.2002] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Epstein-Barr virus (EBV) immediate-early protein BZLF1 is a transcriptional activator that mediates the switch between the latent and the lytic forms of EBV infection. It was previously reported that BZLF1 inhibits p53 transcriptional function in reporter gene assays. Here we further examined the effects of BZLF1 on p53 function by using a BZLF1-expressing adenovirus vector (AdBZLF1). Infection of cells with the AdBZLF1 vector increased the level of cellular p53 but prevented the induction of p53-dependent cellular target genes, such as p21 and MDM2. BZLF1-expressing cells had increased p53-specific DNA binding activity in electrophoretic mobility shift assays, increased p53 phosphorylation at multiple residues (including serines 6, 9, 15, 33, 46, 315, and 392), and increased acetylation at lysine 320 and lysine 382. Thus, the inhibitory effects of BZLF1 on p53 transcriptional function cannot be explained by its effects on p53 phosphorylation, acetylation, or DNA binding activity. BZLF1 substantially reduced the level of cellular TATA binding protein (TBP) in both normal human fibroblasts and A549 cells, and the inhibitory effects of BZLF1 on p53 transcriptional function could be partially rescued by the overexpression of TBP. Thus, BZLF1 has numerous effects on p53 posttranslational modification but may inhibit p53 transcriptional function in part through an indirect mechanism involving the suppression of TBP expression.
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Affiliation(s)
- Amy Mauser
- Department of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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47
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Espejel S, Franco S, Sgura A, Gae D, Bailey SM, Taccioli GE, Blasco MA. Functional interaction between DNA-PKcs and telomerase in telomere length maintenance. EMBO J 2002; 21:6275-87. [PMID: 12426399 PMCID: PMC137185 DOI: 10.1093/emboj/cdf593] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
DNA-PKcs is the catalytic subunit of the DNA-dependent protein kinase (DNA-PK) complex that functions in the non-homologous end-joining of double-strand breaks, and it has been shown previously to have a role in telomere capping. In particular, DNA-PKcs deficiency leads to chromosome fusions involving telomeres produced by leading-strand synthesis. Here, by generating mice doubly deficient in DNA-PKcs and telomerase (Terc(-/-)/DNA-PKcs(-/-)), we demonstrate that DNA-PKcs also has a fundamental role in telomere length maintenance. In particular, Terc(-/-)/DNA-PKcs(-/-) mice displayed an accelerated rate of telomere shortening when compared with Terc(-/-) controls, suggesting a functional interaction between both activities in maintaining telomere length. In addition, we also provide direct demonstration that DNA-PKcs is essential for both end-to-end fusions and apoptosis triggered by critically short telomeres. Our data predict that, in telomerase-deficient cells, i.e. human somatic cells, DNA-PKcs abrogation may lead to a faster rate of telomere degradation and cell cycle arrest in the absence of increased apoptosis and/or fusion of telomere-exhausted chromosomes. These results suggest a critical role of DNA-PKcs in both cancer and aging.
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Affiliation(s)
- Silvia Espejel
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - Sonia Franco
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - Antonella Sgura
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - Darren Gae
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - Susan M. Bailey
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - Guillermo E. Taccioli
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
| | - María A. Blasco
- Department of Immunology and Oncology, National Centre of Biotechnology, E-28049 Madrid, Spain, Department of Biology, University of Rome ‘Roma Tre’, Via le Marconi 446, Rome 00146, Italy, Department of Microbiology, Boston University School of Medicine, Boston, MA 02118-2526 and Department of Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, USA Corresponding author e-mail: S.Espejel, S.Franco and A.Sgura contributed equally to this work
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Minella AC, Swanger J, Bryant E, Welcker M, Hwang H, Clurman BE. p53 and p21 form an inducible barrier that protects cells against cyclin E-cdk2 deregulation. Curr Biol 2002; 12:1817-27. [PMID: 12419181 DOI: 10.1016/s0960-9822(02)01225-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cyclin E, in conjunction with its catalytic partner cdk2, is rate limiting for entry into the S phase of the cell cycle. Cancer cells frequently contain mutations within the cyclin D-Retinoblastoma protein pathway that lead to inappropriate cyclin E-cdk2 activation. Although deregulated cyclin E-cdk2 activity is believed to directly contribute to the neoplastic progression of these cancers, the mechanism of cyclin E-induced neoplasia is unknown. RESULTS We studied the consequences of deregulated cyclin E expression in primary cells and found that cyclin E initiated a p53-dependent response that prevented excess cdk2 activity by inducing expression of the p21Cip1 cdk inhibitor. The increased p53 activity was not associated with increased expression of the p14ARF tumor suppressor. Instead, cyclin E led to increased p53 serine15 phosphorylation that was sensitive to inhibitors of the ATM/ATR family. When either p53 or p21cip1 was rendered nonfunctional, then the excess cyclin E became catalytically active and caused defects in S phase progression, increased ploidy, and genetic instability. CONCLUSIONS We conclude that p53 and p21 form an inducible barrier that protects cells against the deleterious consequences of cyclin E-cdk2 deregulation. A response that restrains cyclin E deregulation is likely to be a general protective mechanism against neoplastic transformation. Loss of this response may thus be required before deregulated cyclin E can become fully oncogenic in cancer cells. Furthermore, the combination of excess cyclin E and p53 loss may be particularly genotoxic, because cells cannot appropriately respond to the cell cycle anomalies caused by excess cyclin E-cdk2 activity.
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Affiliation(s)
- Alex C Minella
- Division of Clinical Research, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA
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49
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Beall EL, Mahoney MB, Rio DC. Identification and Analysis of a Hyperactive Mutant Form of Drosophila P-Element Transposase. Genetics 2002; 162:217-27. [PMID: 12242235 PMCID: PMC1462248 DOI: 10.1093/genetics/162.1.217] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Transposition in many organisms is regulated to control the frequency of DNA damage caused by the DNA breakage and joining reactions. However, genetic studies in prokaryotic systems have led to the isolation of mutant transposase proteins with higher or novel activities compared to those of the wild-type protein. In the course of our study of the effects of mutating potential ATM-family DNA damage checkpoint protein kinase sites in the Drosophila P-element transposase protein, we found one mutation, S129A, that resulted in an elevated level of transposase activity using in vivo recombination assays, including P-element-mediated germline transformation. In vitro assays for P-element transposase activity indicate that the S129A mutant exhibits elevated donor DNA cleavage activity when compared to the wild-type protein, whereas the strand-transfer activity is similar to that of wild type. This difference may reflect the nature of the in vitro assays and that normally in vivo the two reactions may proceed in concert. The P-element transposase protein contains 10 potential consensus phosphorylation sites for the ATM family of PI3-related protein kinases. Of these 10 sites, 8 affect transposase activity either positively or negatively when substituted individually with alanine and tested in vivo. A mutant transposase protein that contains all eight N-terminal serine and threonine residues substituted with alanine is inactive and can be restored to full activity by substitution of wild-type amino acids back at only 3 of the 8 positions. These data suggest that the activity of P-element transposase may be regulated by phosphorylation and demonstrate that one mutation, S129A, results in hyperactive transposition.
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Affiliation(s)
- Eileen L Beall
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3204, USA
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Sasaki MS, Ejima Y, Tachibana A, Yamada T, Ishizaki K, Shimizu T, Nomura T. DNA damage response pathway in radioadaptive response. Mutat Res 2002; 504:101-18. [PMID: 12106651 DOI: 10.1016/s0027-5107(02)00084-2] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Radioadaptive response is a biological defense mechanism in which low-dose ionizing irradiation elicits cellular resistance to the genotoxic effects of subsequent irradiation. However, its molecular mechanism remains largely unknown. We previously demonstrated that the dose recognition and adaptive response could be mediated by a feedback signaling pathway involving protein kinase C (PKC), p38 mitogen activated protein kinase (p38MAPK) and phospholipase C (PLC). Further, to elucidate the downstream effector pathway, we studied the X-ray-induced adaptive response in cultured mouse and human cells with different genetic background relevant to the DNA damage response pathway, such as deficiencies in TP53, DNA-PKcs, ATM and FANCA genes. The results showed that p53 protein played a key role in the adaptive response while DNA-PKcs, ATM and FANCA were not responsible. Wortmannin, a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), mimicked the priming irradiation in that the inhibitor alone rendered the cells resistant against the induction of chromosome aberrations and apoptosis by the subsequent X-ray irradiation. The adaptive response, whether it was afforded by low-dose X-rays or wortmannin, occurred in parallel with the reduction of apoptotic cell death by challenging doses. The inhibitor of p38MAPK which blocks the adaptive response did not suppress apoptosis. These observations indicate that the adaptive response and apoptotic cell death constitute a complementary defense system via life-or-death decisions. The p53 has a pivotal role in channeling the radiation-induced DNA double-strand breaks (DSBs) into an adaptive legitimate repair pathway, where the signals are integrated into p53 by a circuitous PKC-p38MAPK-PLC damage sensing pathway, and hence turning off the signals to an alternative pathway to illegitimate repair and apoptosis. A possible molecular mechanism of adaptive response to low-dose ionizing irradiation has been discussed in relation to the repair of DSBs and implicated to the current controversial observations on the expression of adaptive response.
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Affiliation(s)
- Masao S Sasaki
- Radiation Biology Center, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto, Japan.
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