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He Y, Lian G, Lin S, Ye Z, Li Q. MDM2 Inhibits Axin-Induced p53 Activation Independently of its E3 Ligase Activity. PLoS One 2013; 8:e67529. [PMID: 23826318 PMCID: PMC3694902 DOI: 10.1371/journal.pone.0067529] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 05/20/2013] [Indexed: 11/18/2022] Open
Abstract
MDM2 plays a crucial role in negatively regulating the functions of tumor suppressor p53. Here we show that MDM2 can inhibit Axin-stimulated p53-dependent apoptosis by suppressing p53 phosphorylation at Ser 46 and apoptosis-related p53 transactivational activity. Interestingly, the ubiquitin E3 ligase activity of MDM2 is not required for this inhibitory effect. Mechanically, either wildtype MDM2 or its E3-dead mutant, disrupts the Axin-based HIPK2/p53 complex formation by blocking the binding of p53 and HIPK2 to Axin. MDM2Δp53, a deletion mutant that lacks p53 binding domain fails to exert the inhibitory effect, demonstrating that the interaction of MDM2 and p53, but not its E3 ligase activity toward p53 plays key role in suppressing Axin-stimulated p53 activation. Our results thus have revealed a novel aspect of the mechanism by which MDM2 regulates p53 activities.
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Affiliation(s)
- Ying He
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Guili Lian
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Shuyong Lin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Zhiyun Ye
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Qinxi Li
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
- * E-mail:
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UV-induced Nucleotide Excision Repair (NER) and Photoreactivation Repair (PER) in two trout fish cell lines used in ecotoxicological assessment studies. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 125:51-5. [PMID: 23742810 DOI: 10.1016/j.jphotobiol.2013.05.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2013] [Revised: 05/07/2013] [Accepted: 05/08/2013] [Indexed: 01/12/2023]
Abstract
A better knowledge of DNA repair capacities in permanent fish cell lines would contribute to establish their interest in genotoxicity testing for environmental risk assessment studies including the effects of an increase in solar UV radiations on aquatic organisms. NER (Nucleotide Excision Repair) and PER (Photoreactivation Repair) are the two repair pathways of choice for UV-induced photo-lesions. In the present paper, these repair processes were characterized in the two rainbow trout cell lines, RTGill-W1 and RTL-W1 (liver), by means of a T4-modified comet assay which allowed to follow the cyclobutane pyrimidine dimers repair kinetics specifically. Both repair processes have been found in the cell lines, PER repairing much faster UV lesions than NER, and NER being slightly more efficient in the gill cell line than in the liver one.
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53
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Miki T, Matsumoto T, Zhao Z, Lee CC. p53 regulates Period2 expression and the circadian clock. Nat Commun 2013; 4:2444. [PMID: 24051492 PMCID: PMC3798035 DOI: 10.1038/ncomms3444] [Citation(s) in RCA: 116] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 08/15/2013] [Indexed: 02/06/2023] Open
Abstract
The mechanistic interconnectivity between circadian regulation and the genotoxic stress response remains poorly understood. Here we show that the expression of Period 2 (Per2), a circadian regulator, is directly regulated by p53 binding to a response element in the Per2 promoter. This p53 response element is evolutionarily conserved and overlaps with the E-Box element critical for BMAL1/CLOCK binding and its transcriptional activation of Per2 expression. Our studies reveal that p53 blocks BMAL1/CLOCK binding to the Per2 promoter, leading to repression of Per2 expression. In the suprachiasmatic nucleus (SCN), p53 expression and its binding to the Per2 promoter are under circadian control. Per2 expression in the SCN is altered by p53 deficiency or stabilization of p53 by Nutlin-3. Behaviourally, p53⁻/⁻ mice have a shorter period length that lacks stability, and they exhibit impaired photo-entrainment to a light pulse under a free-running state. Our studies demonstrate that p53 modulates mouse circadian behaviour.
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Affiliation(s)
- Takao Miki
- Department of Biochemistry and Molecular Biology, Medical School, University of Texas Health Science Center-Houston, Houston, Texas 77030
| | - Tomoko Matsumoto
- Department of Biochemistry and Molecular Biology, Medical School, University of Texas Health Science Center-Houston, Houston, Texas 77030
| | - Zhaoyang Zhao
- Department of Biochemistry and Molecular Biology, Medical School, University of Texas Health Science Center-Houston, Houston, Texas 77030
| | - Cheng Chi Lee
- Department of Biochemistry and Molecular Biology, Medical School, University of Texas Health Science Center-Houston, Houston, Texas 77030
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Burrill DR, Inniss MC, Boyle PM, Silver PA. Synthetic memory circuits for tracking human cell fate. Genes Dev 2012; 26:1486-97. [PMID: 22751502 DOI: 10.1101/gad.189035.112] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
A variety of biological phenomena, from disease progression to stem cell differentiation, are typified by a prolonged cellular response to a transient environmental cue. While biologically relevant, heterogeneity in these long-term responses is difficult to assess at the population level, necessitating the development of biological tools to track cell fate within subpopulations. Here we present a novel synthetic biology approach for identifying and tracking mammalian cell subpopulations. We constructed three genomically integrated circuits that use bistable autoregulatory transcriptional feedback to retain memory of exposure to brief stimuli. These "memory devices" are used to isolate and track the progeny of cells that responded differentially to doxycycline, hypoxia, or DNA-damaging agents. Following hypoxic or ultraviolet radiation exposure, strongly responding cells activate the memory device and exhibit changes in gene expression, growth rates, and viability for multiple generations after the initial stimulus. Taken together, these results indicate that a heritable memory of hypoxia and DNA damage exists in subpopulations that differ in long-term cell behavior.
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Affiliation(s)
- Devin R Burrill
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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Xuan C, Wang Q, Han X, Duan Y, Li L, Shi L, Wang Y, Shan L, Yao Z, Shang Y. RBB, a novel transcription repressor, represses the transcription of HDM2 oncogene. Oncogene 2012; 32:3711-21. [PMID: 22926524 DOI: 10.1038/onc.2012.386] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 07/11/2012] [Accepted: 07/13/2012] [Indexed: 01/04/2023]
Abstract
The p53 tumor suppressor is important in many aspects of cell biology. Tight regulation of p53 is thus imperative for maintaining cell homeostasis and preventing tumorigenesis. The stabilization and activity of p53 is primarily regulated by MDM2, which is encoded for by HDM2. However, how the expression and activity of MDM2 is regulated remains largely unknown. Here, we report a novel BTB and BEN domains-containing protein, RBB. We demonstrated that RBB is a novel transcriptional repressor binding specific DNA motif via a homodimer and interacting with the nucleosome remodeling and deacetylase (NuRD) complex. Genome wide transcription target analysis by ChIP sequencing revealed that RBB represses the transcription of a series of functionally important genes including HDM2. We showed that RBB recruits the NuRD complex to the internal promoter of HDM2 and inhibits the expression of MDM2 protein, leading to subsequent stabilization of tumor suppressor p53. Significantly, we showed that RBB suppresses cell proliferation and sensitizes cells to DNA damage-induced apoptosis. Our data indicate that RBB is a novel transcriptional repressor and an important regulator of p53 pathway.
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Affiliation(s)
- C Xuan
- 2011 Collaborative Innovation Center of Tianjin for Medical Epigenetics, Department of Biochemistry and Molecular Biology, Tianjin Key Laboratory of Medical Epigenetics, Tianjin Medical University, Tianjin, China.
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Shih MF, Cherng JY. Protective effects of Chlorella-derived peptide against UVC-induced cytotoxicity through inhibition of caspase-3 activity and reduction of the expression of phosphorylated FADD and cleaved PARP-1 in skin fibroblasts. Molecules 2012; 17:9116-28. [PMID: 22858838 PMCID: PMC6269031 DOI: 10.3390/molecules17089116] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 11/16/2022] Open
Abstract
UVC irradiation induces oxidative stress and leads to cell death through an apoptotic pathway. This apoptosis is caused by activation of caspase-3 and formation of poly(ADP-ribose) polymerase-1 (PARP-1). In this study, the underlying mechanisms of Chlorella derived peptide (CDP) activity against UVC-induced cytotoxicity were investigated. Human skin fibroblasts were treated with CDP, vitamin C, or vitamin E after UVC irradiation for a total energy of 15 J/cm2. After the UVC exposure, cell proliferation and caspase-3 activity were measured at 12, 24, 48, and 72 h later. Expression of phosphorylated FADD and cleaved PARP-1 were measured 16 h later. DNA damage (expressed as pyrimidine (6-4) pyrimidone photoproducts DNA concentration) and fragmentation assay were performed 24 h after the UVC exposure. Results showed that UVC irradiation induced cytotoxicity in all groups except those treated with CDP. The caspase-3 activity in CDP-treated cells was inhibited from 12 h onward. Expression of phosphorylated FADD and cleaved PARP-1 were also reduced in CDP-treated cells. Moreover, UVC-induced DNA damage and fragmentation were also prevented by the CDP treatment. This study shows that treatment of CDP provides protective effects against UVC-induced cytotoxicity through the inhibition of caspase-3 activity and the reduction of phosphorylated FADD and cleaved PARP-1 expression.
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Affiliation(s)
- Mei Fen Shih
- Department of Pharmacy, Chia-Nan University of Pharmacy and Science, Tainan 717, Taiwan
| | - Jong Yuh Cherng
- Department of Chemistry and Biochemistry, National Chung Cheng University, Chia-Yi 621, Taiwan
- Author to whom correspondence should be addressed; ;
Tel.: +886-5-272-0411 (ext. 66416); Fax: +886-5-272-1040
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DNA repair in human pluripotent stem cells is distinct from that in non-pluripotent human cells. PLoS One 2012; 7:e30541. [PMID: 22412831 PMCID: PMC3295811 DOI: 10.1371/journal.pone.0030541] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Accepted: 12/19/2011] [Indexed: 11/19/2022] Open
Abstract
The potential for human disease treatment using human pluripotent stem cells, including embryonic stem cells and induced pluripotent stem cells (iPSCs), also carries the risk of added genomic instability. Genomic instability is most often linked to DNA repair deficiencies, which indicates that screening/characterization of possible repair deficiencies in pluripotent human stem cells should be a necessary step prior to their clinical and research use. In this study, a comparison of DNA repair pathways in pluripotent cells, as compared to those in non-pluripotent cells, demonstrated that DNA repair capacities of pluripotent cell lines were more heterogeneous than those of differentiated lines examined and were generally greater. Although pluripotent cells had high DNA repair capacities for nucleotide excision repair, we show that ultraviolet radiation at low fluxes induced an apoptotic response in these cells, while differentiated cells lacked response to this stimulus, and note that pluripotent cells had a similar apoptotic response to alkylating agent damage. This sensitivity of pluripotent cells to damage is notable since viable pluripotent cells exhibit less ultraviolet light-induced DNA damage than do differentiated cells that receive the same flux. In addition, the importance of screening pluripotent cells for DNA repair defects was highlighted by an iPSC line that demonstrated a normal spectral karyotype, but showed both microsatellite instability and reduced DNA repair capacities in three out of four DNA repair pathways examined. Together, these results demonstrate a need to evaluate DNA repair capacities in pluripotent cell lines, in order to characterize their genomic stability, prior to their pre-clinical and clinical use.
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UV-induced interaction between p38 MAPK and p53 serves as a molecular switch in determining cell fate. FEBS Lett 2010; 584:4711-6. [DOI: 10.1016/j.febslet.2010.10.057] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2010] [Revised: 10/16/2010] [Accepted: 10/26/2010] [Indexed: 12/16/2022]
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Perry ME. The regulation of the p53-mediated stress response by MDM2 and MDM4. Cold Spring Harb Perspect Biol 2010; 2:a000968. [PMID: 20182601 DOI: 10.1101/cshperspect.a000968] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Exquisite control of the activity of p53 is necessary for mammalian survival. Too much p53 is lethal, whereas too little permits tumorigenesis. MDM2 and MDM4 are structurally related proteins critical for the control of p53 activity during development, homeostasis, and the response to stress. These two essential proteins regulate both the activation of p53 in response to stress and the recovery of cells following resolution of the damage, yet both are oncogenic when overexpressed. Thus, multiple regulatory circuits ensure that their activities are fine-tuned to promote tumor-free survival. Numerous diverse stressors activate p53, and much research has gone into trying to find commonalities between them that would explain the mechanism by which p53 becomes active. It is now clear that although these diverse stressors activate p53 by different biochemical pathways, one common feature is the effort they direct, through a variety of means, toward disrupting the functions of both MDM2 and MDM4. This article provides an overview of the relationship between MDM2 and MDM4, features the various biochemical mechanisms by which p53 is activated through inhibition of their functions, and proposes some emerging areas for investigation of the p53-mediated stress response.
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Affiliation(s)
- Mary Ellen Perry
- Laboratory of Protein Dynamics and Signaling, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-0189, USA.
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Latonen L, Järvinen PM, Suomela S, Moore HM, Saarialho-Kere U, Laiho M. Ultraviolet B radiation regulates cysteine-rich protein 1 in human keratinocytes. PHOTODERMATOLOGY PHOTOIMMUNOLOGY & PHOTOMEDICINE 2010; 26:70-7. [PMID: 20415737 DOI: 10.1111/j.1600-0781.2010.00488.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Cysteine-rich protein 1 (CRP1) is a growth-inhibitory cytoskeletal protein that is induced by ultraviolet (UV) C radiation radiation in fibroblasts. Our aim was to investigate the effects of UV radiation on CRP1 in keratinocytes, the main cell type subjected to UV radiation in the human body. METHODS The effects of physiologically relevant doses of UVB radiation on CRP1 protein levels were studied in cultured primary keratinocytes and transformed cell lines (HaCaT, A-431) by immunoblotting. UVB-induced keratinocyte apoptosis was assessed by flow cytometry and monitoring caspase activity. Expression of CRP1 in human skin in vivo was studied by immunohistochemistry in samples of normal skin, actinic keratosis (AK) representing UV-damaged skin and squamous cell carcinoma (SCC), a UV-induced skin cancer. RESULTS CRP1 expression increased by UVB radiation in primary but not in immortalized keratinocytes. Upon high, apoptosis-inducing doses of UV radiation, CRP1 was cleaved in a caspase-dependent manner. In normal skin, CRP1 was expressed in smooth muscle cells, vasculature, sweat glands, sebaceous glands and hair root sheath, but very little CRP1 was present in keratinocytes. CRP1 expression was elevated in basal cells in AK but not in SCC. CONCLUSION CRP1 expression is regulated by UVB in human keratinocytes, suggesting a role for CRP1 in the phototoxic responses of human skin.
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Affiliation(s)
- Leena Latonen
- Haartman Institute, University of Helsinki, Helsinki, Finland.
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62
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Lin J, Yang Q, Wilder PT, Carrier F, Weber DJ. The calcium-binding protein S100B down-regulates p53 and apoptosis in malignant melanoma. J Biol Chem 2010; 285:27487-27498. [PMID: 20587415 DOI: 10.1074/jbc.m110.155382] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The S100B-p53 protein complex was discovered in C8146A malignant melanoma, but the consequences of this interaction required further study. When S100B expression was inhibited in C8146As by siRNA (siRNA(S100B)), wt p53 mRNA levels were unchanged, but p53 protein, phosphorylated p53, and p53 gene products (i.e. p21 and PIDD) were increased. siRNA(S100B) transfections also restored p53-dependent apoptosis in C8146As as judged by poly(ADP-ribose) polymerase cleavage, DNA ladder formation, caspase 3 and 8 activation, and aggregation of the Fas death receptor (+UV); whereas, siRNA(S100B) had no effect in SK-MEL-28 cells containing elevated S100B and inactive p53 (p53R145L mutant). siRNA(S100B)-mediated apoptosis was independent of the mitochondria, because no changes were observed in mitochondrial membrane potential, cytochrome c release, caspase 9 activation, or ratios of pro- and anti-apoptotic proteins (BAX, Bcl-2, and Bcl-X(L)). As expected, cells lacking S100B (LOX-IM VI) were not affected by siRNA(S100B), and introduction of S100B reduced their UV-induced apoptosis activity by 7-fold, further demonstrating that S100B inhibits apoptosis activities in p53-containing cells. In other wild-type p53 cells (i.e. C8146A, UACC-2571, and UACC-62), S100B was found to contribute to cell survival after UV treatment, and for C8146As, the decrease in survival after siRNA(S100B) transfection (+UV) could be reversed by the p53 inhibitor, pifithrin-alpha. In summary, reducing S100B expression with siRNA was sufficient to activate p53, its transcriptional activation activities, and p53-dependent apoptosis pathway(s) in melanoma involving the Fas death receptor and perhaps PIDD. Thus, a well known marker for malignant melanoma, S100B, likely contributes to cancer progression by down-regulating the tumor suppressor protein, p53.
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Affiliation(s)
- Jing Lin
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Maryland 21201
| | - Qingyuan Yang
- Department of Radiation Oncology, University of Maryland School of Medicine, Maryland 21201
| | - Paul T Wilder
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Maryland 21201; Marlene and Stewart Greenebaum Cancer Center, Baltimore, Maryland 21201
| | - France Carrier
- Department of Radiation Oncology, University of Maryland School of Medicine, Maryland 21201; Marlene and Stewart Greenebaum Cancer Center, Baltimore, Maryland 21201.
| | - David J Weber
- Department of Biochemistry & Molecular Biology, University of Maryland School of Medicine, Maryland 21201; Marlene and Stewart Greenebaum Cancer Center, Baltimore, Maryland 21201.
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MDM4 (MDMX) localizes at the mitochondria and facilitates the p53-mediated intrinsic-apoptotic pathway. EMBO J 2009; 28:1926-39. [PMID: 19521340 DOI: 10.1038/emboj.2009.154] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Accepted: 05/18/2009] [Indexed: 02/08/2023] Open
Abstract
MDM4 is a key regulator of p53, whose biological activities depend on both transcriptional activity and transcription-independent mitochondrial functions. MDM4 binds to p53 and blocks its transcriptional activity; however, the main cytoplasmic localization of MDM4 might also imply a regulation of p53-mitochondrial function. Here, we show that MDM4 stably localizes at the mitochondria, in which it (i) binds BCL2, (ii) facilitates mitochondrial localization of p53 phosphorylated at Ser46 (p53Ser46(P)) and (iii) promotes binding between p53Ser46(P) and BCL2, release of cytochrome C and apoptosis. In agreement with these observations, MDM4 reduction by RNA interference increases resistance to DNA-damage-induced apoptosis in a p53-dependent manner and independently of transcription. Consistent with these findings, a significant downregulation of MDM4 expression associates with cisplatin resistance in human ovarian cancers, and MDM4 modulation affects cisplatin sensitivity of ovarian cancer cells. These data define a new localization and function of MDM4 that, by acting as a docking site for p53Ser46(P) to BCL2, facilitates the p53-mediated intrinsic-apoptotic pathway. Overall, our results point to MDM4 as a double-faced regulator of p53.
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Huang XX, Bernerd F, Halliday GM. Ultraviolet A within sunlight induces mutations in the epidermal basal layer of engineered human skin. THE AMERICAN JOURNAL OF PATHOLOGY 2009; 174:1534-43. [PMID: 19264911 DOI: 10.2353/ajpath.2009.080318] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The ultraviolet B (UVB) waveband within sunlight is an important carcinogen; however, UVA is also likely to be involved. By ascribing mutations to being either UVB or UVA induced, we have previously shown that human skin cancers contain similar numbers of UVB- and UVA-induced mutations, and, importantly, the UVA mutations were at the base of the epidermis of the tumors. To determine whether these mutations occurred in response to UV, we exposed engineered human skin (EHS) to UVA, UVB, or a mixture that resembled sunlight, and then detected mutations by both denaturing high-performance liquid chromatography and DNA sequencing. EHS resembles human skin, modeling differential waveband penetration to the basal, dividing keratinocytes. We administered only four low doses of UV exposure. Both UVA and UVB induced p53 mutations in irradiated EHS, suggesting that sunlight doses that are achievable during normal daily activities are mutagenic. UVA- but not UVB-induced mutations predominated in the basal epidermis that contains dividing keratinocytes and are thought to give rise to skin tumors. These studies indicate that both UVA and UVB at physiological doses are mutagenic to keratinocytes in EHS.
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Affiliation(s)
- Xiao Xuan Huang
- Discipline of Dermatology, Bosch Institute, Sydney Cancer Centre, The University of Sydney, New South Wales, Australia
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Stubbert LJ, Smith JM, Hamill JD, Arcand TL, McKay BC. The anti-apoptotic role for p53 following exposure to ultraviolet light does not involve DDB2. Mutat Res 2009; 663:69-76. [PMID: 19428372 DOI: 10.1016/j.mrfmmm.2009.01.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2008] [Revised: 12/24/2008] [Accepted: 01/27/2009] [Indexed: 01/26/2023]
Abstract
The p53 tumour suppressor is a transcription factor that can either activate or repress the expression of specific genes in response to cellular stresses such as exposure to ultraviolet light. The p53 protein can exert both pro- and anti-apoptotic effects depending on cellular context. In primary human fibroblasts, p53 protects cells from UV-induced apoptosis at moderate doses but this is greatly affected by the nucleotide excision repair (NER) capacity of the cells. The damage-specific DNA binding protein 2 (DDB2) is involved in NER and is associated with xeroderma pigmentosum subgroup E (XP-E). Importantly, DDB2 is also positively regulated by the p53 protein. To study the potential interplay between DDB2 and p53 in determining the apoptotic response of primary fibroblasts exposed to UV light, the expression of these proteins was manipulated in primary normal and XP-E fibroblast strains using human papillomavirus E6 protein (HPV-E6), RNA interference and recombinant adenoviruses expressing either p53 or DDB2. Normal and XP-E fibroblast strains were equally sensitive to UV-induced apoptosis over a broad range of doses and disruption of p53 in these strains using HPV-E6 or RNA interference led to a similar increase in apoptosis following exposure to UV light. In contrast, forced expression of p53 or DDB2 did not affect UV-induced apoptosis greatly in these normal or XP-E fibroblast strains. Collectively, these results indicate that p53 is primarily protective against UV-induced apoptosis in primary human fibroblasts and this activity of p53 does not require DDB2.
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Affiliation(s)
- L J Stubbert
- Cancer Therapeutics Program, Ottawa Health Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
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66
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Sakamoto A, Akieda S, Oda Y, Iwamoto Y, Tsuneyoshi M. Mutation analysis of the Gadd45 gene at exon 4 in atypical fibroxanthoma. BMC DERMATOLOGY 2009; 9:1. [PMID: 19128509 PMCID: PMC2628644 DOI: 10.1186/1471-5945-9-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2008] [Accepted: 01/07/2009] [Indexed: 12/02/2022]
Abstract
Background Atypical fibroxanthoma (AFX) histologically mimics high-grade sarcoma in the skin, although it follows a benign clinical course. AFX occurs in the sun-exposed skin and for this reason, an association with ultraviolet light has long been suspected. Bax and Gadd45 are p53 effector proteins. Bax is a programmed cell death protein and belongs to the Bcl-2 family. Gadd45 is a multifunctional DNA damage-inducible gene associated with the process of DNA damage. Methods Immunohistochemical expression of Bax was analyzed in 7 cases of AFX, and in 7 cases of benign fibrous histiocytoma (BFH) used as a comparison. The expression pattern of Bax was compared to previously reported p53 and Gadd45 expressions in a correspondent series. Mutation of the Gadd45 gene at exon 4 was also analyzed in AFX. Results AFX and BFH showed immunoreactivities respectively for Bax (3/7, 0/7), Gadd45 (4/7, 1/7) and p53 (2/7, 0/7). There was no exact correlation between p53 expression and Bax or Gadd45 expression. However, the pattern of expression between Bax and Gadd45 was also the same, with the exception of one case. No mutation of the Gadd45 gene at exon 4 was observed in a series of 6 AFX cases where DNA was available (0/6). Conclusion These results suggest a possible association between Bax and Gadd45 in AFX, and may refute any possibility of dysfunction of Gadd45 in terms of gene mutation, at least at exon 4 of the Gadd45 gene.
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Affiliation(s)
- Akio Sakamoto
- Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
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67
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Kassam SN, Rainbow AJ. UV-inducible base excision repair of oxidative damaged DNA in human cells. Mutagenesis 2008; 24:75-83. [DOI: 10.1093/mutage/gen054] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Gamper AM, Roeder RG. Multivalent binding of p53 to the STAGA complex mediates coactivator recruitment after UV damage. Mol Cell Biol 2008; 28:2517-27. [PMID: 18250150 PMCID: PMC2293101 DOI: 10.1128/mcb.01461-07] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Revised: 10/22/2007] [Accepted: 01/28/2008] [Indexed: 12/29/2022] Open
Abstract
The recruitment of transcriptional coactivators, including histone modifying enzymes, is an important step in transcription regulation. A typical activator is thought to interact with several cofactors, presumably in a sequential manner. The common use of several cofactors raises the question of how activators achieve both cofactor selectivity and diversity. Human STAGA is a multiprotein complex with the acetyltransferase GCN5L as the catalytic subunit. Here, we first show, through RNA interference-mediated knock-down and chromatin immunoprecipitation assays, that GCN5 plays a role in p53-dependent gene activation. We then employ p53 mutagenesis, in vitro binding, protein-protein cross-linking, and chromatin immunoprecipitation assays to establish a novel role for the second p53 activation subdomain (AD2) in STAGA recruitment and, further, to demonstrate that optimal binding of STAGA to p53 involves interactions of STAGA subunits TAF9, GCN5, and ADA2b, respectively, with AD1, AD2, and carboxy-terminal domains of p53. These results provide concrete evidence for mediation of transcription factor binding to coactivator complexes through multiple interactions. Based on our data, we propose a cooperative and modular binding mode for the recruitment of coactivator complexes to promoters.
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Affiliation(s)
- Armin M Gamper
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY 10021, USA
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The absence of Ser389 phosphorylation in p53 affects the basal gene expression level of many p53-dependent genes and alters the biphasic response to UV exposure in mouse embryonic fibroblasts. Mol Cell Biol 2008; 28:1974-87. [PMID: 18195040 DOI: 10.1128/mcb.01610-07] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Phosphorylation is important in p53-mediated DNA damage responses. After UV irradiation, p53 is phosphorylated specifically at murine residue Ser389. Phosphorylation mutant p53.S389A cells and mice show reduced apoptosis and compromised tumor suppression after UV irradiation. We investigated the underlying cellular processes by time-series analysis of UV-induced gene expression responses in wild-type, p53.S389A, and p53(-/-) mouse embryonic fibroblasts. The absence of p53.S389 phosphorylation already causes small endogenous gene expression changes for 2,253, mostly p53-dependent, genes. These genes showed basal gene expression levels intermediate to the wild type and p53(-/-), possibly to readjust the p53 network. Overall, the p53.S389A mutation lifts p53-dependent gene repression to a level similar to that of p53(-/-) but has lesser effect on p53-dependently induced genes. In the wild type, the response of 6,058 genes to UV irradiation was strictly biphasic. The early stress response, from 0 to 3 h, results in the activation of processes to prevent the accumulation of DNA damage in cells, whereas the late response, from 12 to 24 h, relates more to reentering the cell cycle. Although the p53.S389A UV gene response was only subtly changed, many cellular processes were significantly affected. The early response was affected the most, and many cellular processes were phase-specifically lost, gained, or altered, e.g., induction of apoptosis, cell division, and DNA repair, respectively. Altogether, p53.S389 phosphorylation seems essential for many p53 target genes and p53-dependent processes.
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70
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El-Mahdy MA, Zhu Q, Wang QE, Wani G, Patnaik S, Zhao Q, Arafa ES, Barakat B, Mir SN, Wani AA. Naringenin protects HaCaT human keratinocytes against UVB-induced apoptosis and enhances the removal of cyclobutane pyrimidine dimers from the genome. Photochem Photobiol 2007; 84:307-16. [PMID: 18086244 DOI: 10.1111/j.1751-1097.2007.00255.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Many naturally occurring agents are believed to protect against UV-induced skin damage. In this study, we have investigated the effects of naringenin (NG), a naturally occurring citrus flavonone, on the removal of UVB-induced cyclobutane pyrimidine dimers (CPD) from the genome and apoptosis in immortalized p53-mutant human keratinocyte HaCaT cells. The colony-forming assay shows that treatment with NG significantly increases long-term cell survival after UVB irradiation. NG treatment also protects the cells from UVB-induced apoptosis, as indicated by the absence of the 180 base pair DNA ladders and the appearance of sub-G1 peak using agarose gel electrophoresis and flow cytometric analysis, respectively. The UVB-induced poly (ADP-ribose) polymerase-1 (PARP-1) cleavage, caspase activation and Bax/Bcl2 ratio were modulated following NG treatment, indicating an antiapoptotic effect of NG in UVB-damaged cells that occurs at least in part via caspase cascade pathway. Moreover, treatment of UVB-irradiated HaCaT cells with NG enhances the removal of CPD from the genome, as observed by both direct quantitation of CPD in genomic DNA and immuno-localization of the damage within the nuclei. The study provides a molecular basis for the action of NG as a promising natural flavonoid in preventing skin aging and carcinogenesis.
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71
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Latonen L, Järvinen PM, Laiho M. Cytoskeleton-interacting LIM-domain protein CRP1 suppresses cell proliferation and protects from stress-induced cell death. Exp Cell Res 2007; 314:738-47. [PMID: 18177859 DOI: 10.1016/j.yexcr.2007.11.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 10/25/2007] [Accepted: 11/27/2007] [Indexed: 11/19/2022]
Abstract
Members of the cysteine-rich protein (CRP) family are actin cytoskeleton-interacting LIM-domain proteins known to act in muscle cell differentiation. We have earlier found that CRP1, a founding member of this family, is transcriptionally induced by UV radiation in human diploid fibroblasts [M. Gentile, L. Latonen, M. Laiho, Cell cycle arrest and apoptosis provoked by UV radiation-induced DNA damage are transcriptionally highly divergent responses, Nucleic Acids Res. 31 (2003) 4779-4790]. Here we show that CRP1 is induced by growth-inhibitory signals, such as increased cellular density, and cytotoxic stress induced by UV radiation or staurosporine. We found that high levels of CRP1 correlate with differentiation-associated morphology towards the myofibroblast lineage and that expression of ectopic CRP1 suppresses cell proliferation. Following UV- and staurosporine-induced stresses, expression of CRP1 provides a survival advantage evidenced by decreased cellular death and increased cellular metabolic activity and attachment. Our studies identify that CRP1 is a novel stress response factor, and provide evidence for its growth-inhibitory and cytoprotective functions.
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Affiliation(s)
- Leena Latonen
- Molecular Cancer Biology Program, University of Helsinki, PO Box 63, FIN-00014 Helsinki, Finland
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72
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Horikawa-Miura M, Matsuda N, Yoshida M, Okumura Y, Mori T, Watanabe M. The Greater Lethality of UVB Radiation to Cultured Human Cells is Associated with the Specific Activation of a DNA Damage-Independent Signaling Pathway. Radiat Res 2007; 167:655-62. [PMID: 17523842 DOI: 10.1667/rr0448.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Accepted: 11/09/2006] [Indexed: 11/03/2022]
Abstract
UV radiation causes cell death through the activation of various intracellular signaling molecules in both DNA damage-dependent and -independent manners. The ability of middle-wavelength UV (UVB) radiation to form DNA photoproducts is less than that of short-wavelength UV (UVC) radiation; however, the differences between UVB and UVC radiation in the extent of DNA damage-independent signaling and its contribution to cell death have not been well characterized. When cells were irradiated with UVB or UVC radiation at doses that generated equivalent amounts of DNA photoproducts, UVB radiation induced more clonogenic cell death, apoptotic cells, mitochondrial cytochrome C release, and intracellular oxidative stress. Among the signaling molecules examined, levels of p53 phosphorylated at Ser-392 and p38 were higher in UVB-irradiated cells than in UVC-irradiated cells. Both phosphorylations were reduced by treating cells with an antioxidant. Furthermore, an inhibitor of p38 also blocked the phosphorylation of p53 at Ser-392. These results suggest that UVB radiation activates the p38 pathway through the generation of oxidative stress, which merges with the DNA p53 pathway by phosphorylation of p53 at ser392. This greater contribution of the DNA damage-independent pathway in UVB-irradiated cells may explain the greater lethality of UVB radiation.
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Affiliation(s)
- Miwa Horikawa-Miura
- Division of Radiation Biology and Protection, Center for Frontier Life Sciences, Nagasaki University, Nagasaki, Japan
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73
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Courdavault S, Baudouin C, Sauvaigo S, Mouret S, Candéias S, Charveron M, Favier A, Cadet J, Douki T. Unrepaired Cyclobutane Pyrimidine Dimers Do Not Prevent Proliferation of UV-B-irradiated Cultured Human Fibroblasts¶. Photochem Photobiol 2007. [DOI: 10.1111/j.1751-1097.2004.tb00004.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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74
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Dregoesc D, Rybak AP, Rainbow AJ. Increased expression of p53 enhances transcription-coupled repair and global genomic repair of a UVC-damaged reporter gene in human cells. DNA Repair (Amst) 2006; 6:588-601. [PMID: 17196445 DOI: 10.1016/j.dnarep.2006.11.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Revised: 11/20/2006] [Accepted: 11/22/2006] [Indexed: 11/16/2022]
Abstract
Ultraviolet (UV) light-induced DNA damage is repaired by nucleotide excision repair, which is divided into two sub-pathways: global genome repair (GGR) and transcription-coupled repair (TCR). While it is well established that the GGR pathway is dependent on the p53 tumour suppressor protein in human cells, both p53-dependent and p53-independent pathways have been reported for TCR. In the present work, we investigated the role of p53 in both GGR and TCR of a UVC-damaged reporter gene in human fibroblasts. We employed a non-replicating recombinant human adenovirus, AdCA17lacZ, that can efficiently infect human fibroblasts and express the beta-galactosidase (beta-gal) reporter gene under the control of the human cytomegalovirus promoter. We examined host cell reactivation (HCR) of beta-gal expression for the UVC-treated reporter construct in normal fibroblasts and in xeroderma pigmentosum (XP) and Cockayne syndrome (CS) fibroblasts deficient in GGR, TCR, or both. HCR was examined in fibroblasts that had been pre-infected with Ad5p53wt, which expresses wild-type p53, or a control adenovirus, AdCA18luc, which expresses the luciferase gene. We show that increased expression of p53 results in enhanced HCR of the UVC-damaged reporter gene in both untreated and UVC-treated cells for normal, CS-B (TCR-deficient), and XP-C (GGR-deficient), but not XP-A (TCR- and GGR-deficient) fibroblasts. These results indicate an involvement of p53 in both TCR and GGR of the UV-damaged reporter gene in human cells.
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Affiliation(s)
- Diana Dregoesc
- Department of Biology, McMaster University, Hamilton, Ontario L8S 4K1, Canada
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75
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Hsu JC, Dev A, Wing A, Brew CT, Bjeldanes LF, Firestone GL. Indole-3-carbinol mediated cell cycle arrest of LNCaP human prostate cancer cells requires the induced production of activated p53 tumor suppressor protein. Biochem Pharmacol 2006; 72:1714-23. [PMID: 16970927 DOI: 10.1016/j.bcp.2006.08.012] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Revised: 08/14/2006] [Accepted: 08/15/2006] [Indexed: 10/24/2022]
Abstract
Indole-3-carbinol (I3C), a dietary compound found naturally in cruciferous vegetables of the Brassica genus such as broccoli and brussels sprouts, induces a G1 growth arrest of human reproductive cancer cells. We previously reported that in LNCaP prostate cancer cells, I3C down-regulated cyclin-dependent kinase (CDK) 2 activity. In our current study, Western blotting and quantitative RT-PCR demonstrated that I3C treatment increased both the transcripts and protein levels of the CDK2 inhibitor p21(waf1/cip1) (p21). Transfection of luciferase reporter plasmids containing wild-type and mutated p21 promoter fragments revealed that I3C induced p21 gene transcription through a p53 DNA binding element. Oligonucleotide precipitation showed that I3C increased the level of activated p53 nuclear protein that is competent to bind its DNA target site on the p21 promoter. Ablation of p53 production using short interfering RNA (siRNA) prevented that the I3C induced G1 arrest and up-regulation of p21 expression. Western blots using p53 phospho-specific antibodies revealed that I3C treatment increased the levels of three phosphorylated forms of p53 (Ser15, Ser37, Ser392) that are known to contribute to p53 protein stability and greater transactivation potential. Taken together, our results establish that the I3C induced G1 arrest of human prostate cancer cells requires the induced production of the activated phosphorylated forms of p53, which stimulate transcription of the CDK2 inhibitor p21.
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Affiliation(s)
- Jocelyn C Hsu
- Department of Molecular and Cell Biology and The Cancer Research Laboratory, The University of California at Berkeley, Berkeley, CA 94720, USA
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76
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Yonekura I, Takai K, Asai A, Kawahara N, Kirino T. p53 potentiates hippocampal neuronal death caused by global ischemia. J Cereb Blood Flow Metab 2006; 26:1332-40. [PMID: 16538233 DOI: 10.1038/sj.jcbfm.9600293] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Although p53 controls cell death after various stresses, its role in neuronal death after brain ischemia is poorly understood. To address this issue, we subjected p53-deficient (p53-/- and p53+/-) mice (backcrossed for 12 generations with C57BL/6 mice) and wild-type mice (p53+/+) to transient global ischemia by the three-vessel occlusion method. Despite similar severity of ischemia, as shown by anoxic depolarization and cortical blood flow, neuronal death in the hippocampal cornus ammonis (CA)1 region was much more extensive in p53+/+ than in p53-/- mice (surviving neuronal count, 9.3%+/-3.0% versus 61.3%+/-34.0% of nonischemic p53+/+ controls, respectively, P<0.0037). In p53+/- mice, a similar trend was also observed, though not statistically significant (43.5% of nonischemic p53+/+ controls). In p53+/+ mice, p53-like immunoreactivity in hippocampal CA1 neurons was enhanced at 12 h after ischemia, and messenger ribonucleic acid for Bax, a direct downstream target of p53, was also increased. These results indicate that p53 potentiates ischemic neuronal death in vivo and suggest that this molecule could be a therapeutic target in neuronal death after cerebral ischemia.
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Affiliation(s)
- Ichiro Yonekura
- Department of Neurosurgery, Graduate School of Medicine, Faculty of Medicine, University of Tokyo, Tokyo, Japan
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77
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Hakulinen J, Keski-Oja J. ADAM10-mediated Release of Complement Membrane Cofactor Protein during Apoptosis of Epithelial Cells. J Biol Chem 2006; 281:21369-21376. [PMID: 16735514 DOI: 10.1074/jbc.m602053200] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Membrane cofactor protein CD46 controls complement activation on cells, is a receptor for several pathogens, and modulates immune responses by affecting CD8(+) T cells. Cells can release CD46 in an intact form on membrane vesicles and in a truncated form by a metalloproteolytic cleavage. The mechanism of shedding and its relationship to cell physiology has remained unclear. We have found using RNA interference analysis that a disintegrin and metalloproteinase (ADAM) 10 is responsible for the regulated shedding of the ectodomain of CD46 in apoptotic cells. The shedding of CD46 was initiated with staurosporine and UVB. Exposure of cell cultures to either UVB or staurosporine resulted in changes of cell morphology and detachment of cells from their matrices within 8-24 h. During this process CD46 was released both in apoptotic vesicles (vCD46) and proteolytically (sCD46) into the medium. Both the metalloproteinase inhibitor GM6001 and RNA interference of ADAM10 completely prevented the release of sCD46 and increased the expression of vCD46 on HaCaT cell vesicles, suggesting that ADAM10 releases sCD46 from the apoptotic vesicles. To explore whether the release of sCD46 is associated with apoptosis we analyzed the effects of caspase inhibitors. As expected, the inhibition of caspase activity attenuated the characteristic features of apoptosis and also decreased the release of sCD46. Our results reveal ADAM10 as an important regulator of CD46 expression during apoptosis. The ADAM10-mediated release of CD46 from apoptotic vesicles may represent a form of strategy to allow restricted complement activation to deal with modified self.
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Affiliation(s)
- Juha Hakulinen
- Departments of Pathology and Virology, Haartman Institute and Biomedicum Helsinki, University of Helsinki and Helsinki University Hospital, Helsinki 00014, Finland.
| | - Jorma Keski-Oja
- Departments of Pathology and Virology, Haartman Institute and Biomedicum Helsinki, University of Helsinki and Helsinki University Hospital, Helsinki 00014, Finland
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78
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Ohkubo S, Tanaka T, Taya Y, Kitazato K, Prives C. Excess HDM2 impacts cell cycle and apoptosis and has a selective effect on p53-dependent transcription. J Biol Chem 2006; 281:16943-16950. [PMID: 16624812 DOI: 10.1074/jbc.m601388200] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mutational inactivation of p53 is only one of the ways that tumors lose p53 function. An alternate route is through overexpression of HDM2, the negative regulator of p53. To further understand how excess HDM2 regulates p53-mediated functions, we generated H1299 cell clones that constitutively express both ectopic HDM2 and tetracycline-regulated inducible p53. We found that over a range of p53 concentrations constitutively expressed HDM2 did not affect the levels of p53 protein. Nevertheless, cells with excess HDM2 displayed numerous changes in their response to p53. After DNA damage, such cells had both increased p53-mediated G2 arrest and reduced cell death. They also showed selective impairment of p53 target gene induction in that some p53 targets were unaffected whereas others were markedly less well induced in the presence of extra HDM2 protein. We also found that excess HDM2 was correlated with reduced p53 acetylation but did not affect p53 association with target promoters in vivo. Indeed, there was no significant difference in the amount of HDM2 associated with p53 at target promoters that differed in their expression depending on the presence of extra HDM2. Thus, HDM2 can selectively down-regulate the transcription function of p53 without either degrading p53 or affecting the interaction of p53 with target promoters.
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Affiliation(s)
- Shuichi Ohkubo
- Department of Biological Sciences, Columbia University, New York, New York 10027; Cancer Research Laboratory, Taiho Pharmaceutical Co., Ltd., 1-27 Misugidai, Hanno, Saitama 357-8527, Japan
| | - Tomoaki Tanaka
- Department of Biological Sciences, Columbia University, New York, New York 10027
| | - Yoichi Taya
- National Cancer Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan
| | - Kenji Kitazato
- Cancer Research Laboratory, Taiho Pharmaceutical Co., Ltd., 1-27 Misugidai, Hanno, Saitama 357-8527, Japan
| | - Carol Prives
- Department of Biological Sciences, Columbia University, New York, New York 10027.
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79
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Kamis U, Kerimoglu H, Ozkagnici A, Acar H. Frequency of Chromosome 17 Aneuploidy in Primary and Recurrent Pterygium by Interphase-Fluorescence in situ Hybridization. Ophthalmic Res 2006; 38:89-94. [PMID: 16357492 DOI: 10.1159/000090329] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Accepted: 06/22/2005] [Indexed: 11/19/2022]
Abstract
AIM To investigate chromosome 17 numerical aberrations by using fluorescence in situ hybridization (FISH) in pterygia and to find out whether there is any association between chromosome 17 aneuploidy and recurrent pterygia. METHODS Pterygium tissue samples were taken from 21 patients by surgical excision. Eighteen of them had primary and 3 had recurrent pterygium. Peripheral whole blood interphase cells obtained from 11 healthy subjects were assigned as control group. The cells from pterygium tissue and peripheral blood were incubated with a hypotonic solution and fixed in order to obtain interphase nuclei. FISH analysis with chromosome-17-specific alpha-satellite DNA probe was performed on both the interphase nuclei of pterygium tissue (of patients) and peripheral whole blood cells of controls. RESULTS The mean percentage of chromosome 17 aneuploidy was 4.71% for the pterygia group and 4.41% for the controls. No significant difference of chromosome 17 aneuploidy was observed between the patients and the controls. When the group of patients with recurrences was compared with the group without recurrences, there was a significant difference in the frequency of chromosome 17 aneuploidy (U = 17, p = 0.029). CONCLUSIONS Chromosome 17 aneuploidy is probably not an important factor in the formation of pterygium, but it may be related to recurrence.
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Affiliation(s)
- Umit Kamis
- Department of Ophthalmology, Faculty of Medicine, Selçuk University, Konya, Turkey.
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80
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Paulsen MT, Ljungman M. The natural toxin juglone causes degradation of p53 and induces rapid H2AX phosphorylation and cell death in human fibroblasts. Toxicol Appl Pharmacol 2005; 209:1-9. [PMID: 16271620 DOI: 10.1016/j.taap.2005.03.005] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2004] [Revised: 03/04/2005] [Accepted: 03/15/2005] [Indexed: 12/01/2022]
Abstract
Juglone (5-hydroxy-1,4-naphtoquinone) is a natural toxin produced by walnut trees. In this study we show that juglone differentially reduces viability of human cells in culture. Normal fibroblast were found to be especially sensitive to juglone and lost viability primarily through a rapid apoptotic and necrotic response. This response may have been triggered by DNA damage since juglone induced a rapid and strong phosphorylation of H2AX in all phases of the cell cycle. Furthermore, juglone inhibits mRNA synthesis in human fibroblasts in a dose-dependent manner. Surprisingly, juglone caused a drastic reduction of the basal level of p53 in human fibroblasts and this loss could not be fully rescued by proteasome and calpain I inhibitors. However, when cells were pretreated with UV light or ionizing radiation, juglone was not able to reduce the cellular levels of activated p53. Our results show that juglone has multiple effects on cells such as the induction of DNA damage, inhibition of transcription, reduction of p53 protein levels and the induction of cell death.
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Affiliation(s)
- Michelle T Paulsen
- Division of Radiation and Cancer Biology, Department of Radiation Oncology, University of Michigan Medical School, Ann Arbor, MI 48109-0936, USA
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81
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Bochkareva E, Kaustov L, Ayed A, Yi GS, Lu Y, Pineda-Lucena A, Liao JCC, Okorokov AL, Milner J, Arrowsmith CH, Bochkarev A. Single-stranded DNA mimicry in the p53 transactivation domain interaction with replication protein A. Proc Natl Acad Sci U S A 2005; 102:15412-7. [PMID: 16234232 PMCID: PMC1266094 DOI: 10.1073/pnas.0504614102] [Citation(s) in RCA: 231] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Accepted: 09/08/2005] [Indexed: 12/30/2022] Open
Abstract
One of many protein-protein interactions modulated upon DNA damage is that of the single-stranded DNA-binding protein, replication protein A (RPA), with the p53 tumor suppressor. Here we report the crystal structure of RPA residues 1-120 (RPA70N) bound to the N-terminal transactivation domain of p53 (residues 37-57; p53N) and, by using NMR spectroscopy, characterize two mechanisms by which the RPA/p53 interaction can be modulated. RPA70N forms an oligonucleotide/oligosaccharide-binding fold, similar to that previously observed for the ssDNA-binding domains of RPA. In contrast, the N-terminal p53 transactivation domain is largely disordered in solution, but residues 37-57 fold into two amphipathic helices, H1 and H2, upon binding with RPA70N. The H2 helix of p53 structurally mimics the binding of ssDNA to the oligonucleotide/oligosaccharide-binding fold. NMR experiments confirmed that both ssDNA and an acidic peptide mimicking a phosphorylated form of RPA32N can independently compete the acidic p53N out of the binding site. Taken together, our data suggest a mechanism for DNA damage signaling that can explain a threshold response to DNA damage.
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Affiliation(s)
- Elena Bochkareva
- Banting and Best Department of Medical Research & Department of Medical Genetics and Microbiology, University of Toronto, 112 College Street, Toronto, Ontario, Canada M5G 1L6
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82
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Latonen L, Laiho M. Cellular UV damage responses--functions of tumor suppressor p53. Biochim Biophys Acta Rev Cancer 2005; 1755:71-89. [PMID: 15921859 DOI: 10.1016/j.bbcan.2005.04.003] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Revised: 04/07/2005] [Accepted: 04/21/2005] [Indexed: 02/06/2023]
Abstract
DNA damage, provoked by ultraviolet (UV) radiation, evokes a cellular damage response composed of activation of stress signaling and DNA checkpoint functions. These are translated to responses of replicative arrest, damage repair, and apoptosis aimed at cellular recovery from the damage. p53 tumor suppressor is a central stress response protein, activated by multiple endogenous and environmental insults, including UV radiation. The significance of p53 in the DNA damage responses has frequently been reviewed in the context of ionizing radiation or other double strand break (DSB)-inducing agents. Despite partly similar patterns, the molecular events following UV radiation are, however, distinct from the responses induced by DSBs and are profoundly coupled with transcriptional stress. These are illustrated, e.g., by the UV damage-specific translocations of Mdm2, promyelocytic leukemia protein, and nucleophosmin and their interactions with p53. In this review, we discuss UV damage-provoked cellular responses and the functions of p53 in damage recovery and cell death.
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Affiliation(s)
- Leena Latonen
- Molecular and Cancer Biology Program and Haartman Institute, University of Helsinki, PO Box 63, FIN-00014 Helsinki, Finland
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83
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Abstract
Cancers arise as a consequence of the accumulation of multiple genetic mutations in a susceptible cell, resulting in perturbation of regulatory networks that control proliferation, survival, and cellular function. Here, the sources of cellular stress that can cause oncogenic mutations and the responses of cells to DNA damage are reviewed. The role of different repair pathways and the potential for cell- and tissue-specific reliance on individual repair mechanisms are discussed. Evidence for cell- and tissue-specific activation of p53-mediated growth arrest and apoptosis after exposure to an individual genotoxin is assessed and some of the potential mediators of these different responses are provided. These cell- and tissue-specific responses to particular forms of DNA damage are likely to be key determinants of tissue-specific tumour susceptibility, and there is good evidence for genetic variations in these responses. The role that genotoxic agents play in altering the microenvironment to produce indirect effects on tumourigenesis through altered production of free radicals and cytokines that are characteristic of inflammatory-type processes is also evaluated. Changes to the microenvironment as direct or indirect effects of genotoxic stress can be involved in both tumour initiation and progression and may even be a prerequisite for tumourigenesis. Therefore, tumour susceptibility after endogenous or exogenous genotoxic stress represents a balance between cell-intrinsic responses of target cells and changes to the microenvironment. A fuller understanding of cell- and tissue-specific responses, alterations to the microenvironment, and genetic modifiers of these responses could lead to novel prevention and therapeutic strategies for common forms of human malignancy.
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Affiliation(s)
- Philip J Coates
- Cancer Biology and Clinical Pathology Unit, Division of Pathology and Neurosciences, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK.
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84
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He Z, Cho YY, Ma WY, Choi HS, Bode AM, Dong Z. Regulation of Ultraviolet B-induced Phosphorylation of Histone H3 at Serine 10 by Fyn Kinase. J Biol Chem 2005; 280:2446-54. [PMID: 15537652 DOI: 10.1074/jbc.m402053200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Ultraviolet B (UVB) induces phosphorylation of histone H3 at serine 10, and mitogen-activated protein kinases are involved in this signal transduction pathway. Here we provide evidence that Fyn kinase, a member of the Src kinase family, is involved in the UVB-induced phosphorylation of histone H3 at serine 10. UVB distinctly increased Fyn kinase activity and phosphorylation. Fyn kinase inhibitors 4-amino-5-(4-chlorophenyl)-7(t-butyl)pyrazol(3,4-d)pyramide and leflunomide, an Src kinase inhibitor, suppressed both UVB-induced phosphorylation of histone H3 at serine 10 and Fyn kinase activity and phosphorylation. UVB-induced phosphorylation of histone H3 at serine 10 was blocked by either a dominant-negative mutant of Fyn (DNM-Fyn) kinase or small interfering RNA of Fyn kinase. UVB-induced phosphorylation and activities of ERKs and protein kinase B/Akt were markedly inhibited by DNM-Fyn kinase. However, DNM-Fyn kinase did not inhibit UVB-induced phosphorylation of p38 MAPK or c-Jun N-terminal kinases. Active Fyn kinase phosphorylated histone H3 at serine 10 in vitro, and the phosphorylated Fyn kinase could translocate into the nucleus of HaCaT cells. These results indicate that Fyn kinase plays a key role in the UVB-induced phosphorylation of histone H3 at serine 10.
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Affiliation(s)
- Zhiwei He
- Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
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85
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Banerjee G, Gupta N, Kapoor A, Raman G. UV induced bystander signaling leading to apoptosis. Cancer Lett 2004; 223:275-84. [PMID: 15896462 DOI: 10.1016/j.canlet.2004.09.035] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2004] [Accepted: 09/13/2004] [Indexed: 12/17/2022]
Abstract
Human keratinocytes (HaCaT) were exposed to UV (A+B) (UVA-350-400 mJ/cm2 and UVB-30 mJ/cm2) which induces apoptosis as evidenced by MTT assay, DNA laddering, Bax and Fas up-regulation. UV induced apoptotic conditioned media (6 h or earlier) did not cause apoptosis in unexposed cells. However, treatment with conditioned medium collected post UV exposure (1 h) induced Bax in unexposed cells as observed by RT-PCR. The induction of cell death was initiated by conditioned medium collected 12 h after UV exposure and the extent of death was increased progressively when conditioned medium collected 24 or 72 h post UV exposure was used. Medium collected 24 h after UV exposure also increased mitochondrial membrane permeability as determined by rhodamine uptake. Conditioned medium induced apoptosis did not involve reactive oxygen species (ROS) unlike UV induced apoptosis indicating that the apoptosis pathway could be different. Interestingly, at high dilution apototic conditioned medium did not induce apoptosis but actually protected cells from UV insult. The role of nerve growth factor (NGF) in UV induced bystander effects are also discussed.
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Affiliation(s)
- Gautam Banerjee
- Cell and Molecular Biology, Environmental Safety Laboratory, Hindustan Lever Research Centre, Mumbai, India.
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86
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Choi EK, Roberts KP, Griffin RJ, Han T, Park HJ, Song CW, Park HJ. Effect of pH on radiation-induced p53 expression. Int J Radiat Oncol Biol Phys 2004; 60:1264-71. [PMID: 15519799 DOI: 10.1016/j.ijrobp.2004.04.043] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2003] [Revised: 04/09/2004] [Accepted: 04/19/2004] [Indexed: 01/08/2023]
Abstract
PURPOSE In most tumors, the intratumor environment is acidic. The purpose of this study was to elucidate the effect of acidic extracellular environment on the radiation-induced expression of p53 and related molecular signals. METHODS AND MATERIALS Cultured RKO.C human colorectal cancer cells carrying wild-type p53 were used. Cells grown in pH 7.5 medium or pH 6.6 medium were irradiated with gamma-rays, and the expression of p53 and p53 mRNA, as well as the degradation rate of the molecules, was determined. The transcriptional activity for p53 was investigated using cells transfected with a p53 reporter construct. The expression of Mdm2 and the phosphorylation of p53, essential factors for p53 degradation, were also investigated. RESULTS The pH 6.6 environment prolonged the radiation-induced expression of p53 and p53 mRNA. The radiation-induced increase in transcriptional activity of p53 lasted longer in pH 6.6 medium than in pH 7.5 medium. The degradation of p53 was delayed at pH 6.6. The radiation-induced expression of Mdm2 was markedly suppressed, whereas the phosphorylation of p53 was markedly increased after irradiation in pH 6.6 medium. CONCLUSION Acidic environment significantly enhances the radiation-induced expression of p53, partly by increasing the formation of p53 and also partly by slowing down the degradation of p53 through inhibiting p53-Mdm2 complex formation. The potential implication of acidic intratumor microenvironment for the response of tumors to radiotherapy remains to be elucidated.
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Affiliation(s)
- Eun Kyung Choi
- Department of Therapeutic Radiology, College of Medicine, University of Ulsan, Seoul, Korea
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87
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Jin ZH, Matsumoto H, Hayashi S, Hatashita M, Ohtsubo T, Shioura H, Kitai R, Kano E. P53-independent thermosensitization by mitomycin C in human non-small-cell lung cancer cells. Int J Radiat Oncol Biol Phys 2004; 59:852-60. [PMID: 15183489 DOI: 10.1016/j.ijrobp.2004.01.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2003] [Revised: 01/05/2004] [Accepted: 01/23/2004] [Indexed: 11/25/2022]
Abstract
PURPOSE To elucidate the relationship between p53 functions and the interactive effects of the combined treatment with mild hyperthermia and mitomycin C. METHODS AND MATERIALS p53-deficient human non-small-cell lung cancer H1299 cells were transfected with a vector carrying a neomycin-resistant gene (neo) or together with a wild-type or mutant p53 gene. Sensitivities of these transfectants to mild hyperthermia at 42 degrees C, mitomycin C (0.05 microg/mL) at 37 degrees C, or the combination treatment were determined by colony formation assay. After these treatments, the induction of apoptosis, the changes in cell cycle distribution, and the accumulation of Hsp72 were examined. RESULTS The combined treatment resulted in an enhanced cell killing effect in H1299 cells in a p53-independent manner, which was partially the result of an enhancement of heat-induced apoptosis. The treatment also caused a marked G(2)/M arrest in the neo and the mutant p53 cells, but not in the wild-type p53 cells. The subsequent release of G(2)/M arrest was accompanied with an increase in the sub-G(1) fractions. Mitomycin C did not affect the accumulation of Hsp72 induced by hyperthermia in H1299 cells regardless of their p53 gene status. CONCLUSION Our findings demonstrate a p53-independent mechanism for an interactively cytotoxic enhancement by combined treatment with mild hyperthermia and mitomycin C.
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Affiliation(s)
- Zhao-Hui Jin
- Department of Experimental Radiology and Health Physics, Fukui Medical University, Matsuoka, Fukui, Japan
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88
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Courdavault S, Baudouin C, Sauvaigo S, Mouret S, Candéias S, Charveron M, Favier A, Cadet J, Douki T. Unrepaired cyclobutane pyrimidine dimers do not prevent proliferation of UV-B-irradiated cultured human fibroblasts. Photochem Photobiol 2004; 79:145-51. [PMID: 15068027 DOI: 10.1562/0031-8655(2004)079<0145:ucpddn>2.0.co;2] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Mutagenic and carcinogenic UV-B radiation is known to damage DNA mostly through the formation of bipyrimidine photoproducts, including cyclobutane dimers (CPD) and (6-4) photoproducts ((6-4) PP). Using high-performance liquid chromatography coupled to tandem mass spectrometry, we investigated the formation and repair of thymine-thymine (TT) and thymine-cytosine (TC) CPD and (6-4) PP in the DNA of cultured human dermal fibroblasts. A major observation was that the rate of repair of the photoproducts did not depend on the identity of the modified pyrimidines. In addition, removal of CPD was found to significantly decrease with increasing applied UV-B dose, whereas (6-4) PP were efficiently repaired within less than 24 h, irrespective of the dose. As a result, a relatively large amount of CPD remained in the genome 48 h after the irradiation. Because the overall applied doses (<500 J m(-2)) were chosen to induce moderate cytotoxicity, fibroblasts could recover their proliferation capacities after transitory cell cycle arrest, as shown by 5-bromo-2'-deoxyuridine (BrdUrd) incorporation and flow cytometry analysis. It could thus be concluded that UV-B-irradiated cultured primary human fibroblasts normally proliferate 48 h after irradiation despite the presence of high levels of CPD in their genome. These observations emphasize the role of CPD in the mutagenic effects of UV-B.
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Affiliation(s)
- Sophie Courdavault
- Laboratoire Lésions des Acides Nucléiques, Service de Chimie Inorganique et Biologique, CEA/DSM/Département de Recherche Fondamentale sur la Matière Condensée, CEA-Grenoble, France
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89
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Di Girolamo N, Chui J, Coroneo MT, Wakefield D. Pathogenesis of pterygia: role of cytokines, growth factors, and matrix metalloproteinases. Prog Retin Eye Res 2004; 23:195-228. [PMID: 15094131 DOI: 10.1016/j.preteyeres.2004.02.002] [Citation(s) in RCA: 198] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Pterygium is a common ocular surface disease apparently only observed in humans. Chronic UV exposure is a widely accepted aetiological factor in the pathogenesis of this disease and this concept is supported by epidemiological data, ray tracing models and histopathological changes that share common features with UV damaged skin. The mechanism(s) of pterygium formation is incompletely understood. Recent data have provided evidence implicating a genetic component, anti-apoptotic mechanisms, cytokines, growth factors, extracellular matrix remodelling (through the actions of matrix metalloproteinases), immunological mechanisms and viral infections in the pathogenesis of this disease. In this review, the current knowledge on pterygium pathogenesis is summarised, highlighting recent developments. In addition, we provide novel data further demonstrating the complexity of this intriguing disease.
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Affiliation(s)
- Nick Di Girolamo
- Department of Pathology, Inflammatory Diseases Research Unit, School of Medical Sciences, University of New South Wales, Sydney 2052, Australia.
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90
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Mancini F, Gentiletti F, D'Angelo M, Giglio S, Nanni S, D'Angelo C, Farsetti A, Citro G, Sacchi A, Pontecorvi A, Moretti F. MDM4 (MDMX) overexpression enhances stabilization of stress-induced p53 and promotes apoptosis. J Biol Chem 2003; 279:8169-80. [PMID: 14660608 DOI: 10.1074/jbc.m311793200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Rescue of embryonic lethality in MDM4(-/-) mice through concomitant loss of p53 has revealed a functional partnership between the two proteins. Biochemical studies have suggested that MDM4 may act as a negative regulator of p53 levels and activity. On the other hand, MDM4 overexpression has been reported to stabilize p53 levels and to counteract MDM2-degradative activity. We have investigated the functional role of MDM4 overexpression on cell behavior. In both established and primary cells cultured under stress conditions, overexpression of MDM4 significantly increased p53-dependent cell death, in correlation with enhanced induction of the endogenous p53 protein levels. This phenomenon was associated with induced p53 transcriptional activity and increased levels of the proapoptotic protein, Bax. Further, p53 stabilization was accompanied by decreased association of the protein to its negative regulator, MDM2. These findings reveal a novel role for MDM4 by demonstrating that in non-tumor cells under stress conditions it may act as a positive regulator of p53 activity, mainly by controlling p53 levels. They also indicate a major distinction between the biological consequences of MDM4 and MDM2 overexpression.
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Affiliation(s)
- Francesca Mancini
- Laboratory of Molecular Oncogenesis, Regina Elena Cancer Institute, Via delle Messi D'Oro 156, Rome 00158, Italy
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91
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Kurki S, Latonen L, Laiho M. Cellular stress and DNA damage invoke temporally distinct Mdm2, p53 and PML complexes and damage-specific nuclear relocalization. J Cell Sci 2003; 116:3917-25. [PMID: 12915590 DOI: 10.1242/jcs.00714] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Mdm2 is a nucleoplasmic and nucleolar protein interacting with p53 and alternative reading frame (ARF) tumor suppressor proteins. Here we demonstrate relocalization and novel interactions of Mdm2 with the promyelocytic leukemia (PML) protein following cellular stress and DNA damage. We show that Mdm2 and PML interact directly in vivo and in vitro depending on the Mdm2 RING finger domain and the PML C-terminus, and that Mdm2 is recruited to the PML nuclear bodies by overexpression of PML. Cellular stress and DNA damage caused by UV-radiation, downregulation of the proteasome and arsenic trioxide promoted Mdm2 and PML damage-specific nuclear relocalization and interaction in a p53-independent manner. However, in vitro analyses showed that PML, Mdm2 and p53 form trimeric complexes. UV-radiation caused rapid rearrangements of PML nuclear bodies and promoted PML-p53 and PML-Mdm2 complex formation, coinciding with p53 stabilization and preceding p53-Mdm2 interaction suggesting temporally distinct complexes. The results demonstrate novel associations between Mdm2 and PML and show the capacity of PML to participate in the activation and stabilization of p53 in response to cellular stress through PML interaction with Mdm2.
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Affiliation(s)
- Sari Kurki
- Haartman Institute, Biomedicum Helsinki, University of Helsinki, FIN-00014 Helsinki, Finland
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92
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Fukunaga-Takenaka R, Fukunaga K, Tatemichi M, Ohshima H. Nitric oxide prevents UV-induced phosphorylation of the p53 tumor-suppressor protein at serine 46: a possible role in inhibition of apoptosis. Biochem Biophys Res Commun 2003; 308:966-74. [PMID: 12927814 DOI: 10.1016/s0006-291x(03)01516-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Ser-46 of p53 is phosphorylated in response to DNA-damage in vivo, and it plays a pivotal role for apoptotic signaling by p53 through regulating the transcriptional activation of genes involved in apoptosis. We found that the presence of the nitric oxide (NO) donor S-nitroso-N-acetyl-D,L-penicillamine (200-800 microM) during UV-irradiation of MCF-7 cells resulted in a significant reduction in the Ser-46 phosphorylation, compared to the UV-irradiated cells without NO. This reduction occurred independently of cyclic GMP generation and without affecting activities of p53 kinases such as the PI3K family, p38 MAPK, and HIPK2. The presence of NO was found to protect HCT116 human colon tumor cells containing wild-type p53 from UV-induced apoptosis, whereas no apparent inhibitory effect of NO on UV-induced apoptosis was observed in those deficient in p53. Our results suggest that NO-mediated protection of apoptosis is p53-dependent, occurring at least partly through NO-inhibition of phosphorylation of p53 on Ser-46.
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Affiliation(s)
- Rika Fukunaga-Takenaka
- International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon Cedex 08, France
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93
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Abstract
AIM: To explore molecular mechanism of nicotinamide adenine dinucleotide (NADH) antagonization against X-ray induced L02 cells damage.
METHODS: L02 liver cells were cultured in RPMI 1640, exposed to X-ray irradiation and continued to culture in the presence or absence of NADH. Cellular viability was analyzed by routine MTT methods. The percent age of apoptotic cells and positive expressions of p53, bax and bcl-2, fas, fasL proteins were determined by FCM. Level of intracellular ROS was determined by confocal microscope scanning. Morphological change was detected by scanning electron micrograph.
RESULTS: The viability of L02 cells was decreased with increasing dose of X-ray irradiation. NADH could not only eliminate the apoptosis induced by X-ray irradiation, but also up-regulate expression of bcl-2 protein and down-regulate expression of p53, bax, fas and fasL proteins (P < 0.05). At the same time, NADH could reduce level of intracellular ROS in radiated L02 cells.
CONCLUSION: NADH has marked anti-radiation effect, its mechanism may be associated with up-regulation of bcl-2 expression and down-regulation of p53, bax fas and fasL expression, as well as decline of intracellular ROS. However, further investigation of its mechanism is worthwhile.
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Affiliation(s)
- Fa-Quan Liu
- Department of Oncology, Zhujiang Hospital, First Military Medical University, Guangzhou 510282, Guangdong Province, China.
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94
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Gentile M, Latonen L, Laiho M. Cell cycle arrest and apoptosis provoked by UV radiation-induced DNA damage are transcriptionally highly divergent responses. Nucleic Acids Res 2003; 31:4779-90. [PMID: 12907719 PMCID: PMC169943 DOI: 10.1093/nar/gkg675] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
DNA damage caused by UV radiation initiates cellular recovery mechanisms, which involve activation of DNA damage response pathways, cell cycle arrest and apoptosis. To assess cellular transcriptional responses to UVC-induced DNA damage we compared time course responses of human skin fibroblasts to low and high doses of UVC radiation known to induce a transient cellular replicative arrest or apoptosis, respectively. UVC radiation elicited >3-fold changes in 460 out of 12,000 transcripts and 89% of these represented downregulated transcripts. Only 5% of the regulated genes were common to both low and high doses of radiation. Cells inflicted with a low dose of UVC exhibited transcription profiles demonstrating transient regulation followed by recovery, whereas the responses were persistent after the high dose. A detailed clustering analysis and functional classification of the targets implied regulation of biologically divergent responses and suggested involvement of transcriptional and translational machinery, inflammatory, anti-proliferative and anti-angiogenic responses. The data support the notion that UVC radiation induces prominent, dose-dependent downregulation of transcription. However, the data strongly suggest that transcriptional repression is also target gene selective. Furthermore, the results demonstrate that dose-dependent induction of cell cycle arrest and apoptosis by UVC radiation are transcriptionally highly distinct responses.
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Affiliation(s)
- Massimiliano Gentile
- Haartman Institute, University of Helsinki and Helsinki University Central Hospital, FIN-00014 Helsinki, Finland
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95
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Harrod R, Nacsa J, Van Lint C, Hansen J, Karpova T, McNally J, Franchini G. Human immunodeficiency virus type-1 Tat/co-activator acetyltransferase interactions inhibit p53Lys-320 acetylation and p53-responsive transcription. J Biol Chem 2003; 278:12310-8. [PMID: 12501250 DOI: 10.1074/jbc.m211167200] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Patients with AIDS are at increased risk for developing various neoplasms, including Hodgkin's and non-Hodgkin's lymphomas, Kaposi's sarcomas, and anal-rectal carcinomas, suggestive that human immunodeficiency virus type-1 infection might promote establishment of AIDS-related cancers. Tat, the viral trans-activator, can be endocytosed by uninfected cells and has been shown to inhibit p53 functions, providing a candidate mechanism through which the human immunodeficiency virus type-1 might contribute to malignant transformation. Because Tat has been shown to interact with histone acetyltransferase domains of p300/cAMP-responsive element-binding protein (CREB)-binding protein and p300/CREB-binding protein-associated factor, we have investigated whether Tat might alter p53 acetylation and tumor suppressor-responsive transcription. Here, we demonstrate that both Tat and p53 co-localize with p300/CREB-binding protein-associated factor and p300 in nuclei of IMR-32 human neuroblastoma cells and in PC-12 pheochromocytoma cells. Further, p53 trans-activation of the 14-3-3varsigma promoter was markedly repressed by Tat-histone acetyltransferase interactions, and p53 acetylation by p300/CREB-binding protein-associated factor on residue Lys(320) was diminished as a result of Tat-histone acetyltransferase binding in vivo and in vitro. Tat also inhibited p53 acetylation by p300 in a dosage-dependent manner in vitro. Finally, HIV-1-infected Molt-4 cells displayed reduced p53 acetylation on lysines 320 and 373 in response to UV irradiation. Our results allude to a mechanism whereby the human immunodeficiency virus type-1 trans-activator might impair tumor suppressor functions in immune/neuronal-derived cells, thus favoring the establishment of neoplasia during AIDS.
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Affiliation(s)
- Robert Harrod
- Laboratory of Molecular Virology, Department of Biological Sciences, Southern Methodist University, Dallas, Texas 75275-0376, USA.
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96
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Wang W, Takimoto R, Rastinejad F, El-Deiry WS. Stabilization of p53 by CP-31398 inhibits ubiquitination without altering phosphorylation at serine 15 or 20 or MDM2 binding. Mol Cell Biol 2003; 23:2171-81. [PMID: 12612087 PMCID: PMC149465 DOI: 10.1128/mcb.23.6.2171-2181.2003] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
CP-31398, a styrylquinazoline, emerged from a high throughput screen for therapeutic agents that restore a wild-type-associated epitope (monoclonal antibody 1620) on the DNA-binding domain of the p53 protein. We found that CP-31398 can not only restore p53 function in mutant p53-expressing cells but also significantly increase the protein level and promote the activity of wild-type p53 in multiple human cell lines, including ATM-null cells. Cells treated with CP-31398 undergo either cell cycle arrest or apoptosis. Further investigation showed that CP-31398 blocks the ubiquitination and degradation of p53 but not in human papillomavirus E6-expressing cells. Of note, CP-31398 does not block the physical association between p53 and MDM2 in vivo. Moreover, unlike the DNA-damaging agent adriamycin, which induces strong phosphorylation of p53 on serines 15 and 20, CP-31398 exposure leads to no measurable phosphorylation on these sites. We found that CP-31398 could also stabilize exogenous p53 in p53 mutant, wild-type, and p53-null human cells, even in MDM2-null p53(-/-) mouse embryonic fibroblasts. Our results suggest a model wherein CP-31398-mediated stabilization of p53 may result from reduced ubiquitination, leading to high levels of transcriptionally active p53. Further understanding of this mechanism may lead to novel strategies for p53 stabilization and tumor suppression in cancers, even those with absent ARF or high MDM2 expression.
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MESH Headings
- Adenocarcinoma/pathology
- Animals
- Ataxia Telangiectasia Mutated Proteins
- Carcinoma, Non-Small-Cell Lung/pathology
- Cell Cycle Proteins
- Colonic Neoplasms/pathology
- Cyclin-Dependent Kinase Inhibitor p21
- Cyclins/biosynthesis
- Cyclins/genetics
- DNA Damage
- DNA-Binding Proteins
- Doxorubicin/pharmacology
- Female
- Fibroblasts/drug effects
- Fibroblasts/metabolism
- Gene Expression Regulation/drug effects
- Genes, p53
- Humans
- Lung Neoplasms/pathology
- Lymphocytes/drug effects
- Lymphocytes/metabolism
- Mice
- Mice, Knockout
- Neoplasm Proteins/metabolism
- Nuclear Proteins
- Oncogene Proteins, Viral/antagonists & inhibitors
- Oncogene Proteins, Viral/metabolism
- Ovarian Neoplasms/pathology
- Phosphorylation
- Phosphoserine/metabolism
- Protein Binding/drug effects
- Protein Processing, Post-Translational/drug effects
- Protein Serine-Threonine Kinases/deficiency
- Protein Serine-Threonine Kinases/genetics
- Protein Serine-Threonine Kinases/metabolism
- Proto-Oncogene Proteins/deficiency
- Proto-Oncogene Proteins/genetics
- Proto-Oncogene Proteins/metabolism
- Proto-Oncogene Proteins c-mdm2
- Pyrimidines/pharmacology
- Receptors, TNF-Related Apoptosis-Inducing Ligand
- Receptors, Tumor Necrosis Factor/biosynthesis
- Receptors, Tumor Necrosis Factor/genetics
- Repressor Proteins
- Transcription, Genetic/drug effects
- Tumor Cells, Cultured
- Tumor Suppressor Protein p53/chemistry
- Tumor Suppressor Protein p53/deficiency
- Tumor Suppressor Protein p53/drug effects
- Tumor Suppressor Protein p53/metabolism
- Tumor Suppressor Proteins
- Ubiquitin/metabolism
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Affiliation(s)
- Wenge Wang
- Laboratory of Molecular Oncology and Cell Cycle Regulation, Howard Hughes Medical Institute, Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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97
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Latonen L, Kurki S, Pitkänen K, Laiho M. p53 and MDM2 are regulated by PI-3-kinases on multiple levels under stress induced by UV radiation and proteasome dysfunction. Cell Signal 2003; 15:95-102. [PMID: 12401524 DOI: 10.1016/s0898-6568(02)00044-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
p53 is a key stress responsive cellular component. It is negatively regulated by MDM2, which is also its transcriptional target. Here we have studied the involvement of phosphatidylinositol-3-kinases (PI-3-kinase) in the regulation of p53-MDM2 pathway following cellular stress induced by UV damage and proteasomal downregulation. We show that p53 stabilized both by proteasome inhibition and UV damage is transcriptionally active. However, p53 in proteasomally downregulated cells differs from UV-stabilized p53 in its interaction with MDM2, posttranslational modifications and subnuclear localization. It is known that members of PI-3-kinase family are able to directly phosphorylate p53 and MDM2. We show that these kinases regulate p53 accumulation after UV radiation, but accumulation of MDM2 after proteasome inhibition. Both proteins have earlier been shown to translocate into nucleoli after downregulation of the proteasome. We found this effect to be dependent on PI-3-kinase activity but not on any suggested PI-3-kinase phosphorylation site on MDM2. In conclusion, we show here that PI-3-kinases regulate p53-MDM2 pathway on multiple, earlier unknown levels.
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Affiliation(s)
- Leena Latonen
- Department of Virology, Haartman Institute, University of Helsinki and Helsinki University Central Hospital, PO Box 63, FIN-00014 Helsinki, Finland
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98
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Yarosh DB, Boumakis S, Brown AB, Canning MT, Galvin JW, Both DM, Kraus E, O'Connor A, Brown DA. Measurement of UVB-Induced DNA damage and its consequences in models of immunosuppression. Methods 2002; 28:55-62. [PMID: 12231188 DOI: 10.1016/s1046-2023(02)00209-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Exposure to UVB results in formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 photoproducts in DNA. These can be quantified by a variety of techniques including alkaline gel electrophoresis, ELISAs, Southwestern blotting, and immunohistochemistry. Damage to DNA results in activation of damage response pathways, as indicated by Western blotting using antibodies specific for p53 and breast cancer-associated gene 1 (BRCA1) phosphorylation. The signal from DNA damage to activation of these response pathways appears to be mediated by FKBP12-rapamycin-associated protein (FRAP), since these phosphorylation events are blocked by rapamycin. UVB-induced DNA damage also leads to induction of immunosuppressive cytokines including tumor necrosis factor alpha (TNF-alpha) and interleukin (IL)-10 in skin. Induction of TNF-alpha by UVB is readily detectable in cultured normal human epidermal keratinocytes (NHEKs) using ELISA, while induction of IL-10 is readily detectable in cultured mouse keratinocytes but not in NHEKs. Induction of DNA damage by liposome-encapsulated HindIII results in induction of immunosuppressive responses similar to UVB. Clinical testing shows that liposome-encapsulated T4 endonuclease V or photolyase stimulates repair of CPDs in the skin of human subjects, and prevents UVB-induced immunosuppression. Stimulation of repair and prevention of immunosuppression have been linked to prevention of skin cancer by liposome-encapsulated T4 endonuclease V in repair-deficient xeroderma pigmentosum patients.
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99
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Nakamura H, Fukami H, Hayashi Y, Kiyono T, Nakatsugawa S, Hamaguchi M, Ishizaki K. Establishment of immortal normal and ataxia telangiectasia fibroblast cell lines by introduction of the hTERT gene. JOURNAL OF RADIATION RESEARCH 2002; 43:167-174. [PMID: 12238331 DOI: 10.1269/jrr.43.167] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
To establish immortal human cells, we introduced the human catalytic subunit of telomerase (hTERT) gene into skin fibroblast cells obtained from normal and ataxia telangiectasia (AT) individuals of Japanese origin. After hTERT introduction, these cells continue to grow beyond a population doubling number of 200 while maintaining their original radiosensitivity. Inductions of p53, phosphorylation of Ser15 in p53, and induction of p21 by X-ray irradiation in immortal cells derived from normal individual were not affected by the hTERT introduction. Both normal and AT immortal cells exhibited an apparent inhibition of growth as original primary cells when they reached confluence. Karyotype analysis has revealed that they are in a diploid range. These results suggest that cells immortalized by hTERT introduction retain their original characteristics except for immortalization, and that they may be useful for analyzing various effects of radiation on human cells.
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Affiliation(s)
- Hideaki Nakamura
- Central Laboratory and Radiation Biology, Aichi Cancer Center Research Institute, Department of Molecular Pathogenesis, Nagoya University School of Medicine, Nagoya, Japan.
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Buzek J, Latonen L, Kurki S, Peltonen K, Laiho M. Redox state of tumor suppressor p53 regulates its sequence-specific DNA binding in DNA-damaged cells by cysteine 277. Nucleic Acids Res 2002; 30:2340-8. [PMID: 12034820 PMCID: PMC117181 DOI: 10.1093/nar/30.11.2340] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2002] [Revised: 04/04/2002] [Accepted: 04/04/2002] [Indexed: 11/12/2022] Open
Abstract
Using a bio-oligo pull-down DNA-binding assay we investigated the binding capacity of endogenous, DNA damage-induced p53 in human diploid fibroblasts to several p53-responsive elements (REs) present in p53-regulated genes. During the course of p53 accumulation, we observed a decrease in p53 binding to the GADD45 but not to the p21(WAF1/CIP1) RE. Using mutated GADD45 sequences we show that this change is dependent on the presence of cytosines at position 3 in RE pentamers and on the p53 redox state. Site-directed mutagenesis experiments demonstrated that Cys277 (a residue directly contacting base 3 in a RE pentamer) is critical for differential regulation of GADD45 in DNA-damaged cells. These data represent a novel mechanism for differential affinity of p53 to distinct REs.
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Affiliation(s)
- Jiri Buzek
- Department of Virology, Haartman Institute, and Molecular Cancer Biology Program, Biomedicum Helsinki, University of Helsinki and Helsinki University Central Hospital Laboratory Diagnostics, PO Box 63, FIN-00014 Helsinki, Finland
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