1
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Li Y, Liang ZY, Wang HL. N6-methyl-2'-deoxyadenosine promotes self-renewal of BFU-E progenitor in erythropoiesis. iScience 2023; 26:106924. [PMID: 37283807 PMCID: PMC10239700 DOI: 10.1016/j.isci.2023.106924] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/08/2023] [Accepted: 05/15/2023] [Indexed: 06/08/2023] Open
Abstract
Red blood cells supply the oxygen required for all human cells and are in demand for emerging blood-loss therapy. Here we identified N6-methyl-2'-deoxyadenosine (6mdA) as an agonist that promotes the hyperproliferation of burst-forming unit erythroid (BFU-E) progenitor cells. In addition, 6mdA represses the apoptosis of erythroid progenitor cells (EPCs). Combined use of with SCF and EPO enabled cultures of isolated BFU-E to be expanded up to 5,000-fold. Transcriptome analysis showed that 6mdA upregulates the expression of the EPC-associated factors c-Kit, Myb, and Gata2 and downregulates that of the erythroid maturation-related transcription factors Gata1, Spi1, and Klf1. Mechanistic studies suggested that 6mdA enhances and prolongs the activation of erythropoiesis-associated master gene c-Kit and its downstream signaling, leading to expansion and accumulation of EPCs. Collectively, we demonstrate that 6mdA can efficiently stimulate the EPC hyperproliferation and provide a new regenerative medicine recipe to improve ex vivo generation of red blood cells.
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Affiliation(s)
- Yao Li
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zi-Yu Liang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hai-Lin Wang
- State Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Institute of Environment and Health, Jianghan University, Wuhan, Hubei 430056, China
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2
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Repositioning Drugs for Rare Diseases Based on Biological Features and Computational Approaches. Healthcare (Basel) 2022; 10:healthcare10091784. [PMID: 36141396 PMCID: PMC9498751 DOI: 10.3390/healthcare10091784] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 09/12/2022] [Accepted: 09/14/2022] [Indexed: 11/16/2022] Open
Abstract
Rare diseases are a group of uncommon diseases in the world population. To date, about 7000 rare diseases have been documented. However, most of them do not have a known treatment. As a result of the relatively low demand for their treatments caused by their scarce prevalence, the pharmaceutical industry has not sufficiently encouraged the research to develop drugs to treat them. This work aims to analyse potential drug-repositioning strategies for this kind of disease. Drug repositioning seeks to find new uses for existing drugs. In this context, it seeks to discover if rare diseases could be treated with medicines previously indicated to heal other diseases. Our approaches tackle the problem by employing computational methods that calculate similarities between rare and non-rare diseases, considering biological features such as genes, proteins, and symptoms. Drug candidates for repositioning will be checked against clinical trials found in the scientific literature. In this study, 13 different rare diseases have been selected for which potential drugs could be repositioned. By verifying these drugs in the scientific literature, successful cases were found for 75% of the rare diseases studied. The genetic associations and phenotypical features of the rare diseases were examined. In addition, the verified drugs were classified according to the anatomical therapeutic chemical (ATC) code to highlight the types with a higher predisposition to be repositioned. These promising results open the door for further research in this field of study.
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3
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Chung WH. Pleiotropic Effects of Caffeine Leading to Chromosome Instability and Cytotoxicity in Eukaryotic Microorganisms. J Microbiol Biotechnol 2021; 31:171-180. [PMID: 33397827 PMCID: PMC9706025 DOI: 10.4014/jmb.2011.11042] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/20/2020] [Accepted: 11/22/2020] [Indexed: 12/15/2022]
Abstract
Caffeine, a methylxanthine analog of purine bases, is a compound that is largely consumed in beverages and medications for psychoactive and diuretic effects and plays many beneficial roles in neuronal stimulation and enhancement of anti-tumor immune responses by blocking adenosine receptors in higher organisms. In single-cell eukaryotes, however, caffeine somehow impairs cellular fitness by compromising cell wall integrity, inhibiting target of rapamycin (TOR) signaling and growth, and overriding cell cycle arrest caused by DNA damage. Among its multiple inhibitory targets, caffeine specifically interacts with phosphatidylinositol 3-kinase (PI3K)-related kinases causing radiosensitization and cytotoxicity via specialized intermediate molecules. Caffeine potentiates the lethality of cells in conjunction with several other stressors such as oxidants, irradiation, and various toxic compounds through largely unknown mechanisms. In this review, recent findings on caffeine effects and cellular detoxification schemes are highlighted and discussed with an emphasis on the inhibitory interactions between caffeine and its multiple targets in eukaryotic microorganisms such as budding and fission yeasts.
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Affiliation(s)
- Woo-Hyun Chung
- College of Pharmacy, Duksung Women’s University, Seoul 0369, Republic of Korea,Innovative Drug Center, Duksung Women’s University, Seoul 01369, Republic of Korea,Corresponding author Phone: +82-2-901-8737 Fax: +82-2-901-8386 E-mail:
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4
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Ren X, Jiang K, Zhang F. The Multifaceted Roles of RCC1 in Tumorigenesis. Front Mol Biosci 2020; 7:225. [PMID: 33102517 PMCID: PMC7522611 DOI: 10.3389/fmolb.2020.00225] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 08/11/2020] [Indexed: 01/31/2023] Open
Abstract
RCC1 (regulator of chromosome condensation 1) is the only known guanine nucleotide exchange factor of Ran, a nuclear Ras-like G protein. RCC1 combines with chromatin and Ran to establish a concentration gradient of RanGTP, thereby participating in a series of cell physiological activities. In this review, we discuss the structure of RCC1 and describe how RCC1 affects the formation and function of the nuclear envelope, spindle formation, and nuclear transport. We mainly focus on the effect of RCC1 on the cell cycle during tumorigenesis and the recent research progress that has been made in relation to different tumor types.
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Affiliation(s)
- Xuanqi Ren
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Kai Jiang
- College of Life Sciences, Shanghai Normal University, Shanghai, China
| | - Feng Zhang
- College of Life Sciences, Shanghai Normal University, Shanghai, China
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5
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Gray JL, von Delft F, Brennan PE. Targeting the Small GTPase Superfamily through Their Regulatory Proteins. Angew Chem Int Ed Engl 2020; 59:6342-6366. [PMID: 30869179 PMCID: PMC7204875 DOI: 10.1002/anie.201900585] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/11/2019] [Indexed: 12/11/2022]
Abstract
The Ras superfamily of small GTPases are guanine-nucleotide-dependent switches essential for numerous cellular processes. Mutations or dysregulation of these proteins are associated with many diseases, but unsuccessful attempts to target the small GTPases directly have resulted in them being classed as "undruggable". The GTP-dependent signaling of these proteins is controlled by their regulators; guanine nucleotide exchange factors (GEFs), GTPase activating proteins (GAPs), and in the Rho and Rab subfamilies, guanine nucleotide dissociation inhibitors (GDIs). This review covers the recent small molecule and biologics strategies to target the small GTPases through their regulators. It seeks to critically re-evaluate recent chemical biology practice, such as the presence of PAINs motifs and the cell-based readout using compounds that are weakly potent or of unknown specificity. It highlights the vast scope of potential approaches for targeting the small GTPases in the future through their regulatory proteins.
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Affiliation(s)
- Janine L. Gray
- Structural Genomics ConsortiumUniversity of Oxford, NDMRBOld Road CampusOxfordOX3 7DQUK
- Target Discovery InstituteNuffield Department of MedicineUniversity of OxfordOld Road CampusOxfordOX3 7FZUK
- Diamond Light SourceHarwell Science and Innovation CampusDidcotOX11 0QXUK
| | - Frank von Delft
- Structural Genomics ConsortiumUniversity of Oxford, NDMRBOld Road CampusOxfordOX3 7DQUK
- Diamond Light SourceHarwell Science and Innovation CampusDidcotOX11 0QXUK
- Department of BiochemistryUniversity of JohannesburgAuckland Park2006South Africa
| | - Paul E. Brennan
- Structural Genomics ConsortiumUniversity of Oxford, NDMRBOld Road CampusOxfordOX3 7DQUK
- Target Discovery InstituteNuffield Department of MedicineUniversity of OxfordOld Road CampusOxfordOX3 7FZUK
- Alzheimer's Research (UK) Oxford Drug Discovery InstituteNuffield Department of MedicineUniversity of OxfordOxfordOX3 7FZUK
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6
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Gray JL, Delft F, Brennan PE. Targeting der kleinen GTPasen über ihre regulatorischen Proteine. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.201900585] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- Janine L. Gray
- Structural Genomics ConsortiumUniversity of Oxford, NDMRB Old Road Campus Oxford OX3 7DQ Großbritannien
- Target Discovery InstituteNuffield Department of MedicineUniversity of Oxford Old Road Campus Oxford OX3 7FZ Großbritannien
- Diamond Light Source Harwell Science and Innovation Campus Didcot OX11 0QX Großbritannien
| | - Frank Delft
- Structural Genomics ConsortiumUniversity of Oxford, NDMRB Old Road Campus Oxford OX3 7DQ Großbritannien
- Diamond Light Source Harwell Science and Innovation Campus Didcot OX11 0QX Großbritannien
- Department of BiochemistryUniversity of Johannesburg Auckland Park 2006 Südafrika
| | - Paul E. Brennan
- Structural Genomics ConsortiumUniversity of Oxford, NDMRB Old Road Campus Oxford OX3 7DQ Großbritannien
- Target Discovery InstituteNuffield Department of MedicineUniversity of Oxford Old Road Campus Oxford OX3 7FZ Großbritannien
- Alzheimer's Research (UK) Oxford Drug Discovery InstituteNuffield Department of MedicineUniversity of Oxford Oxford OX3 7FZ Großbritannien
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7
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Chang YL, Hsu YJ, Chen Y, Wang YW, Huang SM. Theophylline exhibits anti-cancer activity via suppressing SRSF3 in cervical and breast cancer cell lines. Oncotarget 2017; 8:101461-101474. [PMID: 29254178 PMCID: PMC5731888 DOI: 10.18632/oncotarget.21464] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 09/18/2017] [Indexed: 11/25/2022] Open
Abstract
Caffeine, theophylline, and theobromine are the most well-known members of methylxanthines. Caffeine-induced serine/arginine-rich splicing factor 2, SRSF2, and SRSF3 are required for the alternative splicing of a subset of cancer-associated genes. However, it remains to be investigated whether and how theophylline and theobromine as well as caffeine exert their antitumor effects through mediating the alternative splicing process. Here, we reveal that theophylline down-regulated SRSF3 expression and switched p53 from alpha into a beta isoform as caffeine did in HeLa and MCF-7 cells via the reverse-transcriptase polymerase chain reaction and Western blot analysis. Further functional studies show that theophylline induced cellular apoptosis, senescence, and decreased colony formation. Interestingly, theophylline had a suppressive effect on cellular proliferation, whereas caffeine enhanced cellular proliferation rates via the 5-bromo-2-deoxyuridine analysis. Theophylline and caffeine had no effect on MCF-10A cells, which is a normal breast cell line. Our results provide an insight that theophylline as well as caffeine could be repurposed as antitumor leading compounds via the downregulation of splicing factor SRSF3 and its target genes.
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Affiliation(s)
- Yung-Lung Chang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Yu-Juei Hsu
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China.,Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Ying Chen
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Yi-Wen Wang
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan, Republic of China
| | - Shih-Ming Huang
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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8
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Huntoon CJ, Flatten KS, Wahner Hendrickson AE, Huehls AM, Sutor SL, Kaufmann SH, Karnitz LM. ATR inhibition broadly sensitizes ovarian cancer cells to chemotherapy independent of BRCA status. Cancer Res 2013; 73:3683-91. [PMID: 23548269 DOI: 10.1158/0008-5472.can-13-0110] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Replication stress and DNA damage activate the ATR-Chk1 checkpoint signaling pathway that licenses repair and cell survival processes. In this study, we examined the respective roles of the ATR and Chk1 kinases in ovarian cancer cells using genetic and pharmacologic inhibitors in combination with cisplatin, topotecan, gemcitabine, and the PARP inhibitor veliparib (ABT-888), four agents with clinical activity in ovarian cancer. RNA interference (RNAi)-mediated depletion or inhibition of ATR sensitized ovarian cancer cells to all four agents. In contrast, while cisplatin, topotecan, and gemcitabine each activated Chk1, RNAi-mediated depletion or inhibition of this kinase in cells sensitized them only to gemcitabine. Unexpectedly, we found that neither the ATR kinase inhibitor VE-821 nor the Chk1 inhibitor MK-8776 blocked ATR-mediated Chk1 phosphorylation or autophosphorylation, two commonly used readouts for inhibition of the ATR-Chk1 pathway. Instead, their ability to sensitize cells correlated with enhanced CDC25A levels. In addition, we also found that VE-821 could further sensitize BRCA1-depleted cells to cisplatin, topotecan, and veliparib beyond the potent sensitization already caused by their deficiency in homologous recombination. Taken together, our results established that ATR and Chk1 inhibitors differentially sensitize ovarian cancer cells to commonly used chemotherapy agents and that Chk1 phosphorylation status may not offer a reliable marker for inhibition of the ATR-Chk1 pathway. A key implication of our work is the clinical rationale it provides to evaluate ATR inhibitors in combination with PARP inhibitors in BRCA1/2-deficient cells.
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Affiliation(s)
- Catherine J Huntoon
- Divisions of Oncology Research and Medical Oncology, and Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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9
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Kaczanowski A, Kiersnowska M. Inactivation of a macronuclear intra-S-phase checkpoint in Tetrahymena thermophila with caffeine affects the integrity of the micronuclear genome. Protist 2011; 162:616-36. [PMID: 21601521 DOI: 10.1016/j.protis.2011.01.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 01/23/2011] [Indexed: 01/16/2023]
Abstract
Aphidicolin (APH), an inhibitor of DNA polymerase α, arrested cell divisions in Tetrahymena thermophila. Surprisingly, low concentrations of APH induced an increase of macronuclear DNA content and cell size in non-dividing cells. In spite of the cell size increase, most proliferation of basal bodies, ciliogenesis and development of new oral primordia were prevented by the APH treatment. The division arrest induced by APH was partly overridden by caffeine (CAF) treatment, which caused the fragmentation ("pulverization") of the chromosomes in G2 micronuclei. Somatic progeny of dividers with pulverized micronuclei (APH+CAF strains) contained aneuploid and amicronucleate cells. The amicronucleate cells, after losing their oral structures and most of their cilia, and undergoing progressive disorganization of cortical structures, assumed an irregular shape ("crinkled") and were nonviable. "Crinkled" cells were not formed after APH + CAF treatment of the amicronuclear BI3840 strain, which contains some mic-specific sequences in its macronucleus. Most of the APH +CAF strains had a typical "*"- like conjugation phenotype: they did not produce pronuclei, but received them unilaterally from their mates and retained old macronuclei. However, 4 among 100 APH+CAF clones induced arrest at meiotic metaphase I in their wt mates. It is likely that the origin of such clones was enhanced by chromosome pulverization.
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10
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Cerella C, Coppola S, Maresca V, De Nicola M, Radogna F, Ghibelli L. Multiple mechanisms for hydrogen peroxide-induced apoptosis. Ann N Y Acad Sci 2009; 1171:559-63. [PMID: 19723104 DOI: 10.1111/j.1749-6632.2009.04901.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The mechanisms of cell killing by oxidative stress, in particular by hydrogen peroxide, are not yet well clarified. Here, we show that during recovery after H(2)O(2) treatment, apoptosis occurs in two different waves, peaking at 8 h (early) and 18 h (late) of recovery from oxidative stress. The two peaks are differentially modulated by a set of inhibitors of metabolic processes, which suggests that the first peak depends on DNA break formation, whereas the second may be correlated with H(2)O(2)-induced mitochondrial alterations.
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11
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Goyal R, Chatterjee S, Bishnoi S. Voltammetric Determination of 2′-Deoxyadenosine and Adenine in Urine of Patients with Hepatocellular Carcinoma Using Fullerene-C60-modified Glassy Carbon Electrode. ELECTROANAL 2009. [DOI: 10.1002/elan.200804533] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Guervilly JH, Macé-Aimé G, Rosselli F. Loss of CHK1 function impedes DNA damage-induced FANCD2 monoubiquitination but normalizes the abnormal G2 arrest in Fanconi anemia. Hum Mol Genet 2007; 17:679-89. [PMID: 18029388 DOI: 10.1093/hmg/ddm340] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Fanconi anemia (FA) is a cancer-prone hereditary disease resulting from mutations in one of the 13 genes defining the FANC/BRCA pathway. This pathway is involved in the cellular resistance to DNA-cross-linking agents. How the FANC/BRCA pathway is activated and why its deficiency leads to the accumulation of FA cells with a 4N DNA content are still poorly answered questions. We investigated the involvement of ATR pathway members in these processes. We show here that RAD9 and RAD17 are required for DNA interstrand cross-link (ICL) resistance and for the optimal activation of FANCD2. Moreover, we demonstrate that CHK1 and its interacting partner CLASPIN that act downstream in the ATR pathway are required for both FANCD2 monoubiquitination and assembling in subnuclear foci in response to DNA damage. Paradoxically, in the absence of any genotoxic stress, CHK1 or CLASPIN depletion results in an increased basal level of FANCD2 monoubiquitination and focalization. We also demonstrate that the ICL-induced accumulation of FA cells in late S/G2 phase is dependent on ATR and CHK1. In agreement with this, CHK1 phosphorylation is enhanced in FA cells, and chemical inhibition of the ATR/CHK1 axis in FA lymphoblasts decreases their sensitivity to mitomycin C. In conclusion, this work describes a complex crosstalk between CHK1 and the FANC/BRCA pathway: CHK1 activates this pathway through FANCD2 monoubiquitination, whereas FA deficiency leads to a CHK1-dependent G2 accumulation, raising the possibility that the FANC/BRCA pathway downregulates CHK1 activation.
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Affiliation(s)
- Jean-Hugues Guervilly
- Equipe voie FANC/BRCA et Cancer, CNRS FRE2939, CEA LRC43V, Univ Paris-Sud, Institut Gustave Roussy, 39 rue Camille Desmoulins, 94805 Villejuif, France
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13
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Bode AM, Dong Z. The enigmatic effects of caffeine in cell cycle and cancer. Cancer Lett 2007; 247:26-39. [PMID: 16709440 PMCID: PMC2824565 DOI: 10.1016/j.canlet.2006.03.032] [Citation(s) in RCA: 125] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2005] [Revised: 03/29/2006] [Accepted: 03/30/2006] [Indexed: 02/08/2023]
Abstract
Caffeine may very well be the most frequently ingested neuroactive drug in the world. Mechanistically, caffeine has been reported to affect cell cycle function, induce programmed cell death or apoptosis and perturb key cell cycle regulatory proteins. Although the effects of caffeine have been heavily investigated, much of the research data regarding caffeine's effects on cell cycle and proliferation seem ambiguous. One important factor may be that caffeine has been used experimentally in numerous cell types under a variety of conditions at concentrations ranging from micromolar to high millimolar. Physiologically, achieving experimental blood levels of caffeine would be extremely difficult without adverse side effects. Therefore, the relevance of experimental data obtained by using high concentrations of caffeine is not clear and may account for some of the discrepancies in the literature. This review attempts to reconcile data regarding the cellular effects of caffeine by examining reported effects on cell cycle, proliferation and apoptosis with careful attention to differences in experimental conditions and caffeine concentration utilized.
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Affiliation(s)
- Ann M. Bode
- The Hormel Institute, University of Minnesota, 801 16th Avenue N.E., Austin, MN 55912, USA
| | - Zigang Dong
- The Hormel Institute, University of Minnesota, 801 16th Avenue N.E., Austin, MN 55912, USA
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14
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Rybaczek D, Maszewski J. Phosphorylation of H2AX histones in response to double-strand breaks and induction of premature chromatin condensation in hydroxyurea-treated root meristem cells of Raphanus sativus, Vicia faba, and Allium porrum. PROTOPLASMA 2007; 230:31-9. [PMID: 17111099 DOI: 10.1007/s00709-006-0192-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Accepted: 03/22/2006] [Indexed: 05/12/2023]
Abstract
Histone H2A variant H2AX is rapidly phosphorylated on the induction of DNA double-strand breaks by ionizing radiation and hydroxyurea-mediated replication arrest, resulting in the formation of gamma-H2AX foci along megabase chromatin domains nearby the sites of incurred DNA damage. In an attempt to establish a relationship between species-specific nuclear architecture and H2AX phosphorylation in S/G(2) phase-arrested root meristem cells, immunocytochemical comparisons using an antibody raised against human gamma-H2AX were made among three plants differing with respect to DNA contents: Allium porrum, representing a reticulate type of DNA package, Vicia faba, having semireticulate cell nuclei, and Raphanus sativus, characterised by a chromocentric type of chromatin. Another approach was aimed at determining possible correlations between the extent of hydroxyurea-induced phosphorylation of H2AX histones and the quantities of root meristem cells induced by caffeine to enter aberrant mitotic division (premature chromosome condensation). It was concluded that the higher-order structure of chromatin may contribute to the accessibility of molecular factors engaged in the recognition and repair of genetic lesions. Consequently, in contrast to A. porrum and V. faba, a diffuse chromatin in chromocentric cell nuclei of R. sativus may become more vulnerable both to generate DNA double-strand breaks and to recruit molecular elements needed to arrange the cell cycle checkpoint functions, and thus, more resistant to factors which allow the cells to enter premature chromosome condensation spontaneously. On the other hand, however, caffeine-mediated overriding of the S-M checkpoint control system resulted in the typical appearance of premature chromosome condensation, irrespective of the genomic content of DNA.
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Affiliation(s)
- Dorota Rybaczek
- Department of Cytophysiology, University of Łódź, Łódź, Poland.
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15
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Itakura E, Umeda K, Sekoguchi E, Takata H, Ohsumi M, Matsuura A. ATR-dependent phosphorylation of ATRIP in response to genotoxic stress. Biochem Biophys Res Commun 2004; 323:1197-202. [PMID: 15451423 DOI: 10.1016/j.bbrc.2004.08.228] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2004] [Indexed: 10/26/2022]
Abstract
PI-kinase-related protein kinase ATR forms a complex with ATRIP and plays pivotal roles in maintaining genome integrity. When DNA is damaged, the ATR-ATRIP complex is recruited to chromatin and is activated to transduce the checkpoint signal, but the precise kinase activation mechanism remains unknown. Here, we show that ATRIP is phosphorylated in an ATR-dependent manner after genotoxic stimuli. The serine 68 and 72 residues are important for the phosphorylation in vivo and are required exclusively for direct modification by ATR in vitro. Using phospho-specific antibody, we demonstrated that phosphorylated ATRIP accumulates at foci induced by DNA damage. Moreover, the loss of phosphorylation does not lead to detectable changes in the relocalization of ATRIP to nuclear foci nor in the activation of downstream effector proteins. Collectively, our results suggest that the ATR-mediated phosphorylation of ATRIP at Ser-68 and -72 is dispensable for the initial response to DNA damage.
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Affiliation(s)
- Eisuke Itakura
- Department of Geriatric Research, National Institute for Longevity Sciences, Obu, Aichi, Japan
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16
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Alderton GK, Joenje H, Varon R, Børglum AD, Jeggo PA, O'Driscoll M. Seckel syndrome exhibits cellular features demonstrating defects in the ATR-signalling pathway. Hum Mol Genet 2004; 13:3127-38. [PMID: 15496423 DOI: 10.1093/hmg/ddh335] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
To date, the only reported genetic defect identified in the developmental disorder, Seckel syndrome, is a mutation in ataxia telangiectasia and Rad3-related protein (ATR). Seckel syndrome is clinically and genetically heterogeneous and whether defects in ATR significantly contribute to Seckel syndrome is unclear. Firstly, we characterize ATR-Seckel cells for their response to DNA damage. ATR-Seckel cells display impaired phosphorylation of ATR-dependent substrates, impaired G2/M checkpoint arrest and elevated micronucleus (MN) formation following exposure to UV and agents that cause replication stalling. We describe a novel phenotype, designated nuclear fragmentation (NF), that occurs following replication arrest. Finally, we report that ATR-Seckel cells have an endogenously increased number of centrosomes in mitotic cells demonstrating a novel role for ATR in regulating centrosome stability. We exploit these phenotypes to examine cell lines derived from additional unrelated Seckel syndrome patients. We show that impaired phosphorylation of ATR-dependent substrates is a common but not invariant feature of Seckel syndrome cell lines. In contrast, all cell lines displayed defective G2/M arrest, increased levels of NF and MN formation following exposure to agents that cause replication stalling. All the Seckel syndrome cell lines examined showed increased endogenous centrosome numbers. Though ATR cDNA can complement the defects in ATR-Seckel cells, it failed to complement any of the additional cell lines. We conclude that Seckel syndrome represents a further damage response disorder that is uniquely associated with defects in the ATR-signalling pathway resulting in failed checkpoint arrest following exposure to replication fork stalling.
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Affiliation(s)
- Gemma K Alderton
- Genome Damage and Stability Centre, University of Sussex, East Sussex, BN1 9RQ, UK
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17
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Cortez D. Caffeine inhibits checkpoint responses without inhibiting the ataxia-telangiectasia-mutated (ATM) and ATM- and Rad3-related (ATR) protein kinases. J Biol Chem 2003; 278:37139-45. [PMID: 12847089 DOI: 10.1074/jbc.m307088200] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The ataxia-telangiectasia-mutated (ATM) and ATM- and Rad3-related (ATR) kinases regulate cell cycle checkpoints by phosphorylating multiple substrates including the CHK1 and -2 protein kinases and p53. Caffeine has been widely used to study ATM and ATR signaling because it inhibits these kinases in vitro and overcomes cell cycle checkpoint responses in vivo. Thus, caffeine has been thought to overcome the checkpoint through its ability to prevent phosphorylation of ATM and ATR substrates. Surprisingly, I have found that multiple ATM-ATR substrates including CHK1 and -2 are hyperphosphorylated in cells treated with caffeine and genotoxic agents such as hydroxyurea or ionizing radiation. ATM autophosphorylation in cells is also increased when caffeine is used in combination with inhibitors of replication suggesting that ATM activity is not inhibited in vivo by caffeine. Furthermore, CHK1 hyperphosphorylation induced by caffeine in combination with hydroxyurea is ATR-dependent suggesting that ATR activity is stimulated by caffeine. Finally, the G2/M checkpoint in response to ionizing radiation or hydroxyurea is abrogated by caffeine treatment without a corresponding decrease in ATM-ATR-dependent signaling. This data suggests that although caffeine is an inhibitor of ATM-ATR kinase activity in vitro, it can block checkpoints without inhibiting ATM-ATR activation in vivo.
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Affiliation(s)
- David Cortez
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA.
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