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Snyers L, Laffer S, Löhnert R, Weipoltshammer K, Schöfer C. CX-5461 causes nucleolar compaction, alteration of peri- and intranucleolar chromatin arrangement, an increase in both heterochromatin and DNA damage response. Sci Rep 2022; 12:13972. [PMID: 35978024 PMCID: PMC9385865 DOI: 10.1038/s41598-022-17923-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 08/02/2022] [Indexed: 11/09/2022] Open
Abstract
In this study, we characterize the changes in nucleolar morphology and its dynamics induced by the recently introduced compound CX-5461, an inhibitor of ribosome synthesis. Time-lapse imaging, immunofluorescence and ultrastructural analysis revealed that exposure of cells to CX-5461 has a profound impact on their nucleolar morphology and function: nucleoli acquired a compact, spherical shape and display enlarged, ring-like masses of perinucleolar condensed chromatin. Tunnels consisting of chromatin developed as transient structures running through nucleoli. Nucleolar components involved in rRNA transcription, fibrillar centres and dense fibrillar component with their major constituents ribosomal DNA, RNA polymerase I and fibrillarin maintain their topological arrangement but become reduced in number and move towards the nucleolar periphery. Nucleolar changes are paralleled by an increased amount of the DNA damage response indicator γH2AX and DNA unwinding enzyme topoisomerase I in nucleoli and the perinucleolar area suggesting that CX-5461 induces torsional stress and DNA damage in rDNA. This is corroborated by the irreversibility of the observed altered nucleolar phenotypes. We demonstrate that incubation with CX-5461, apart from leading to specific morphological alterations, increases senescence and decreases cell replication. We discuss that these alterations differ from those observed with other drugs interfering with nucleolar functions.
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Affiliation(s)
- Luc Snyers
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstr. 17, 1090, Vienna, Austria
| | - Sylvia Laffer
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstr. 17, 1090, Vienna, Austria
| | - Renate Löhnert
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstr. 17, 1090, Vienna, Austria
| | - Klara Weipoltshammer
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstr. 17, 1090, Vienna, Austria
| | - Christian Schöfer
- Department for Cell and Developmental Biology, Center for Anatomy and Cell Biology, Medical University of Vienna, Schwarzspanierstr. 17, 1090, Vienna, Austria.
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2
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Targeting Ribosome Biogenesis in Cancer: Lessons Learned and Way Forward. Cancers (Basel) 2022; 14:cancers14092126. [PMID: 35565259 PMCID: PMC9100539 DOI: 10.3390/cancers14092126] [Citation(s) in RCA: 29] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 04/18/2022] [Accepted: 04/22/2022] [Indexed: 01/05/2023] Open
Abstract
Simple Summary Cells need to produce ribosomes to sustain continuous proliferation and expand in numbers, a feature that is even more prominent in uncontrollably proliferating cancer cells. Certain cancer cell types are expected to depend more on ribosome biogenesis based on their genetic background, and this potential vulnerability can be exploited in designing effective, targeted cancer therapies. This review provides information on anti-cancer molecules that target the ribosome biogenesis machinery and indicates avenues for future research. Abstract Rapid growth and unrestrained proliferation is a hallmark of many cancers. To accomplish this, cancer cells re-wire and increase their biosynthetic and metabolic activities, including ribosome biogenesis (RiBi), a complex, highly energy-consuming process. Several chemotherapeutic agents used in the clinic impair this process by interfering with the transcription of ribosomal RNA (rRNA) in the nucleolus through the blockade of RNA polymerase I or by limiting the nucleotide building blocks of RNA, thereby ultimately preventing the synthesis of new ribosomes. Perturbations in RiBi activate nucleolar stress response pathways, including those controlled by p53. While compounds such as actinomycin D and oxaliplatin effectively disrupt RiBi, there is an ongoing effort to improve the specificity further and find new potent RiBi-targeting compounds with improved pharmacological characteristics. A few recently identified inhibitors have also become popular as research tools, facilitating our advances in understanding RiBi. Here we provide a comprehensive overview of the various compounds targeting RiBi, their mechanism of action, and potential use in cancer therapy. We discuss screening strategies, drug repurposing, and common problems with compound specificity and mechanisms of action. Finally, emerging paths to discovery and avenues for the development of potential biomarkers predictive of therapeutic outcomes across cancer subtypes are also presented.
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3
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Sanz G, Singh M, Peuget S, Selivanova G. Inhibition of p53 inhibitors: progress, challenges and perspectives. J Mol Cell Biol 2020; 11:586-599. [PMID: 31310659 PMCID: PMC6735775 DOI: 10.1093/jmcb/mjz075] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Revised: 06/10/2019] [Accepted: 06/14/2019] [Indexed: 12/20/2022] Open
Abstract
p53 is the major tumor suppressor and the most frequently inactivated gene in cancer. p53 could be disabled either by mutations or by upstream negative regulators, including, but not limited to MDM2 and MDMX. p53 activity is required for the prevention as well as for the eradication of cancers. Restoration of p53 activity in mouse models leads to the suppression of established tumors of different origin. These findings provide a strong support to the anti-cancer strategy aimed for p53 reactivation. In this review, we summarize recent progress in the development of small molecules, which restore the tumor suppressor function of wild-type p53 and discuss their clinical advance. We discuss different aspects of p53-mediated response, which contribute to suppression of tumors, including non-canonical p53 activities, such as regulation of immune response. While targeting p53 inhibitors is a very promising approach, there are certain limitations and concerns that the intensive research and clinical evaluation of compounds will hopefully help to overcome.
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Affiliation(s)
- Gema Sanz
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Madhurendra Singh
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Sylvain Peuget
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
| | - Galina Selivanova
- Department of Microbiology, Tumor and Cell Biology, Biomedicum 8C, Karolinska Institute, Sweden
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4
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Abstract
The nucleolus is a prominent subnuclear compartment, where ribosome biosynthesis takes place. Recently, the nucleolus has gained attention for its novel role in the regulation of cellular stress. Nucleolar stress is emerging as a new concept, which is characterized by diverse cellular insult-induced abnormalities in nucleolar structure and function, ultimately leading to activation of p53 or other stress signaling pathways and alterations in cell behavior. Despite a number of comprehensive reviews on this concept, straightforward and clear-cut way criteria for a nucleolar stress state, regarding the factors that elicit this state, the morphological and functional alterations as well as the rationale for p53 activation are still missing. Based on literature of the past two decades, we herein summarize the evolution of the concept and provide hallmarks of nucleolar stress. Along with updated information and thorough discussion of existing confusions in the field, we pay particular attention to the current understanding of the sensing mechanisms, i.e., how stress is integrated by p53. In addition, we propose our own emphasis regarding the role of nucleolar protein NPM1 in the hallmarks of nucleolar stress and sensing mechanisms. Finally, the links of nucleolar stress to human diseases are briefly and selectively introduced.
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Affiliation(s)
- Kai Yang
- Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China.,Shanghai Key Laboratory for Prevention and Treatment of Bone and Joint Diseases with Integrated Chinese-Western Medicine, Shanghai Institute of Traumatology and Orthopedics, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, 197 Ruijin 2nd Road, Shanghai, 200025, China
| | - Jie Yang
- Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China
| | - Jing Yi
- Shanghai Key Laboratory for Tumor Microenvironment and Inflammation, Department of Biochemistry and Molecular Cell Biology, Shanghai Jiao Tong University School of Medicine, 280 South Chongqing Road, Shanghai, 200025, China
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5
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Caudron-Herger M, Pankert T, Seiler J, Németh A, Voit R, Grummt I, Rippe K. Alu element-containing RNAs maintain nucleolar structure and function. EMBO J 2015; 34:2758-74. [PMID: 26464461 DOI: 10.15252/embj.201591458] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 08/31/2015] [Indexed: 01/05/2023] Open
Abstract
Non-coding RNAs play a key role in organizing the nucleus into functional subcompartments. By combining fluorescence microscopy and RNA deep-sequencing-based analysis, we found that RNA polymerase II transcripts originating from intronic Alu elements (aluRNAs) were enriched in the nucleolus. Antisense-oligo-mediated depletion of aluRNAs or drug-induced inhibition of RNA polymerase II activity disrupted nucleolar structure and impaired RNA polymerase I-dependent transcription of rRNA genes. In contrast, overexpression of a prototypic aluRNA sequence increased both nucleolus size and levels of pre-rRNA, suggesting a functional link between aluRNA, nucleolus integrity and pre-rRNA synthesis. Furthermore, we show that aluRNAs interact with nucleolin and target ectopic genomic loci to the nucleolus. Our study suggests an aluRNA-based mechanism that links RNA polymerase I and II activities and modulates nucleolar structure and rRNA production.
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Affiliation(s)
- Maïwen Caudron-Herger
- Genome Organization & Function, German Cancer Research Center (DKFZ) Bioquant Center, Heidelberg, Germany
| | - Teresa Pankert
- Genome Organization & Function, German Cancer Research Center (DKFZ) Bioquant Center, Heidelberg, Germany
| | - Jeanette Seiler
- Molecular Biology of the Cell II, German Cancer Research Center, Heidelberg, Germany
| | - Attila Németh
- Department of Biochemistry III, Biochemistry Center Regensburg University of Regensburg, Regensburg, Germany
| | - Renate Voit
- Molecular Biology of the Cell II, German Cancer Research Center, Heidelberg, Germany
| | - Ingrid Grummt
- Molecular Biology of the Cell II, German Cancer Research Center, Heidelberg, Germany
| | - Karsten Rippe
- Genome Organization & Function, German Cancer Research Center (DKFZ) Bioquant Center, Heidelberg, Germany
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6
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Řezníčková E, Weitensteiner S, Havlíček L, Jorda R, Gucký T, Berka K, Bazgier V, Zahler S, Kryštof V, Strnad M. Characterization of a Pyrazolo[4,3-d]pyrimidine Inhibitor of Cyclin-Dependent Kinases 2 and 5 and Aurora A With Pro-Apoptotic and Anti-Angiogenic ActivityIn Vitro. Chem Biol Drug Des 2015. [DOI: 10.1111/cbdd.12618] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Eva Řezníčková
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Sabine Weitensteiner
- Department of Pharmacy; LMU Munich - Center for Drug Research - Pharmaceutical Biology; Butenandtstr. 5-13 81377 Munich Germany
| | - Libor Havlíček
- Isotope Laboratory; Institute of Experimental Botany ASCR; Vídeňská 1083 14220 Prague Czech Republic
| | - Radek Jorda
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Tomáš Gucký
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Karel Berka
- Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry; Faculty of Science; Palacký University; 17. listopadu 12 77146 Olomouc Czech Republic
| | - Václav Bazgier
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
- Department of Physical Chemistry; Faculty of Science; Palacký University; 17. listopadu 1192/12 771 46 Olomouc Czech Republic
| | - Stefan Zahler
- Department of Pharmacy; LMU Munich - Center for Drug Research - Pharmaceutical Biology; Butenandtstr. 5-13 81377 Munich Germany
| | - Vladimír Kryštof
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
| | - Miroslav Strnad
- Laboratory of Growth Regulators & Department of Chemical Biology and Genetics; Centre of the Region Haná for Biotechnological and Agricultural Research; Palacký University and Institute of Experimental Botany AS CR; Šlechtitelů 27 78371 Olomouc Czech Republic
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Lam YW, Trinkle-Mulcahy L. New insights into nucleolar structure and function. F1000PRIME REPORTS 2015; 7:48. [PMID: 26097721 PMCID: PMC4447046 DOI: 10.12703/p7-48] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The nucleolus is a non-membrane-bound nuclear organelle found in all eukaryotes. It is the quintessential ‘RNA-seeded’ nuclear body, forming around specific chromosomal features called nucleolar organizing regions that contain arrays of ribosomal DNA. Assembly is triggered by activation of RNA polymerase I-mediated transcription and regulated in mammalian cells in a cell cycle-dependent manner. Although the nucleolus is best known for its role in coordinating ribosome biogenesis, biochemical and proteomic analyses have revealed a much wider functional complexity than previously appreciated, including roles in cell cycle regulation, DNA damage sensing and repair, pre-mRNA processing, telomere metabolism, processing of non-coding RNAs, and coordination of the cellular response to various stresses. Despite these advances, much remains to be learned about the full range of biological processes that occur within, or involve, this organelle and how its assembly/disassembly and functional reorganization in response to various stimuli are regulated. Here, we review the impact of recent studies that provide major insights into these fundamental questions, and we highlight the therapeutic potential of targeting nucleolar pathways.
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Affiliation(s)
- Yun Wah Lam
- Department of Biology and Chemistry, City University of Hong KongTat Chee Avenue, KowloonHong Kong
| | - Laura Trinkle-Mulcahy
- Department of Cellular & Molecular Medicine and Ottawa Institute of Systems Biology, University of Ottawa451 Smyth Road, Ottawa, ON, K1H 8M5Canada
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8
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Quin JE, Devlin JR, Cameron D, Hannan KM, Pearson RB, Hannan RD. Targeting the nucleolus for cancer intervention. Biochim Biophys Acta Mol Basis Dis 2014; 1842:802-16. [PMID: 24389329 DOI: 10.1016/j.bbadis.2013.12.009] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Accepted: 12/17/2013] [Indexed: 12/17/2022]
Abstract
The contribution of the nucleolus to cancer is well established with respect to its traditional role in facilitating ribosome biogenesis and proliferative capacity. More contemporary studies however, infer that nucleoli contribute a much broader role in malignant transformation. Specifically, extra-ribosomal functions of the nucleolus position it as a central integrator of cellular proliferation and stress signaling, and are emerging as important mechanisms for modulating how oncogenes and tumor suppressors operate in normal and malignant cells. The dependence of certain tumor cells to co-opt nucleolar processes to maintain their cancer phenotypes has now clearly been demonstrated by the application of small molecule inhibitors of RNA Polymerase I to block ribosomal DNA transcription and disrupt nucleolar function (Bywater et al., 2012 [1]). These drugs, which selectively kill tumor cells in vivo while sparing normal cells, have now progressed to clinical trials. It is likely that we have only just begun to scratch the surface of the potential of the nucleolus as a new target for cancer therapy, with "suppression of nucleolar stress" representing an emerging "hallmark" of cancer. This article is part of a Special Issue entitled: Role of the Nucleolus in Human Disease.
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Affiliation(s)
- Jaclyn E Quin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Jennifer R Devlin
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Donald Cameron
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia
| | - Kate M Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia
| | - Richard B Pearson
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Ross D Hannan
- Oncogenic Signalling and Growth Control Program, Peter MacCallum Cancer Centre, East Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, Victoria, Australia; Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, Victoria, Australia; Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia; School of Biomedical Sciences, The University of Queensland, St Lucia, Queensland, Australia.
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9
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Abstract
This article focuses on drug targeting to specific cellular organelles for therapeutic purposes. Drugs can be delivered to all major organelles of the cell (cytosol, endosome/lysosome, nucleus, nucleolus, mitochondria, endoplasmic reticulum, Golgi apparatus, peroxisomes and proteasomes) where they exert specific effects in those particular subcellular compartments. Delivery can be achieved by chemical (e.g., polymeric) or biological (e.g., signal sequences) means. Unidirectional targeting to individual organelles has proven to be immensely successful for drug therapy. Newer technologies that accommodate multiple signals (e.g., protein switch and virus-like delivery systems) mimic nature and allow for a more sophisticated approach to drug delivery. Harnessing different methods of targeting multiple organelles in a cell will lead to better drug delivery and improvements in disease therapy.
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10
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Reduced expression of ribosomal proteins relieves microRNA-mediated repression. Mol Cell 2012; 46:171-86. [PMID: 22541556 DOI: 10.1016/j.molcel.2012.04.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 02/16/2012] [Accepted: 04/05/2012] [Indexed: 01/16/2023]
Abstract
MicroRNAs (miRNAs) regulate physiological and pathological processes by inducing posttranscriptional repression of target messenger RNAs (mRNAs) via incompletely understood mechanisms. To discover factors required for human miRNA activity, we performed an RNAi screen using a reporter cell line of miRNA-mediated repression of translation initiation. We report that reduced expression of ribosomal protein genes (RPGs) dissociated miRNA complexes from target mRNAs, leading to increased polysome association, translation, and stability of miRNA-targeted mRNAs relative to untargeted mRNAs. RNA sequencing of polysomes indicated substantial overlap in sets of genes exhibiting increased or decreased polysomal association after Argonaute or RPG knockdowns, suggesting similarity in affected pathways. miRNA profiling of monosomes and polysomes demonstrated that miRNAs cosediment with ribosomes. RPG knockdowns decreased miRNAs in monosomes and increased their target mRNAs in polysomes. Our data show that most miRNAs repress translation and that the levels of RPGs modulate miRNA-mediated repression of translation initiation.
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11
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Pfeuty B. Strategic cell-cycle regulatory features that provide mammalian cells with tunable G1 length and reversible G1 arrest. PLoS One 2012; 7:e35291. [PMID: 22558136 PMCID: PMC3339863 DOI: 10.1371/journal.pone.0035291] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 03/14/2012] [Indexed: 12/25/2022] Open
Abstract
Transitions between consecutive phases of the eukaryotic cell cycle are driven by the catalytic activity of selected sets of cyclin-dependent kinases (Cdks). Yet, their occurrence and precise timing is tightly scheduled by a variety of means including Cdk association with inhibitory/adaptor proteins (CKIs). Here we focus on the regulation of G1-phase duration by the end of which cells of multicelled organisms must decide whether to enter S phase or halt, and eventually then, differentiate, senesce or die to obey the homeostatic rules of their host. In mammalian cells, entry in and progression through G1 phase involve sequential phosphorylation and inactivation of the retinoblastoma Rb proteins, first, by cyclin D-Cdk4,6 with the help of CKIs of the Cip/Kip family and, next, by the cyclin E-Cdk2 complexes that are negatively regulated by Cip/Kip proteins. Using a dynamical modeling approach, we show that the very way how the Rb and Cip/Kip regulatory modules interact differentially with cyclin D-Cdk4,6 and cyclin E-Cdk2 provides to mammalian cells a powerful means to achieve an exquisitely-sensitive control of G1-phase duration and fully reversible G1 arrests. Consistently, corruption of either one of these two modules precludes G1 phase elongation and is able to convert G1 arrests from reversible to irreversible. This study unveils fundamental design principles of mammalian G1-phase regulation that are likely to confer to mammalian cells the ability to faithfully control the occurrence and timing of their division process in various conditions.
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Affiliation(s)
- Benjamin Pfeuty
- Laboratoire de Physique des Lasers, Atomes, et Molécules, CNRS, UMR8523, Université Lille 1 Sciences et Technologies, Villeneuve d'Ascq, France.
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12
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Turner AJ, Knox AA, Watkins NJ. Nucleolar disruption leads to the spatial separation of key 18S rRNA processing factors. RNA Biol 2012; 9:175-86. [PMID: 22418842 DOI: 10.4161/rna.18811] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Many chemotherapeutic drugs cause the downregulation of ribosome production and the disruption of nucleolar function. This stabilizes p53 and leads to either cell cycle arrest or apoptosis. It is not clear, however, how these agents cause nucleolar disruption and block ribosome production. The small subunit (SSU) processome, which has been primarily studied in yeast, is responsible for the processing of the 18S rRNA and assembly of the small ribosomal subunit. Here we have characterized the human homologs of seven SSU processome components. Furthermore, we have investigated the effects of three chemotherapeutic drugs, Actinomycin D (ActD), camptothecin (CPT) and 5,6-dichloro-1-β-D-ribofuranosylbenzimidazole (DRB) on the subcellular distribution of key SSU processome components and the formation of this processing complex. Interestingly, ActD- and DRB-treatment resulted in the majority of U3 small nucleolar RNP (snoRNP) localizing separately to other key components of the SSU processome. All three agents affected RNA polymerase I transcription, primarily at the level of elongation but only ActD resulted in a clear reduction in SSU processome levels. Taken together, our data indicate that different chemotherapeutic agents, each of which initiates a stress response and cause nucleolar disruption, have different effects on the formation and localization of the SSU processome.
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Affiliation(s)
- Amy Jane Turner
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK
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13
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Anticancer activity of a low immunogenic protein toxin (BMP1) from Indian toad (Bufo melanostictus, Schneider) skin extract. Toxicon 2011; 58:85-92. [PMID: 21635912 DOI: 10.1016/j.toxicon.2011.05.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2011] [Revised: 05/14/2011] [Accepted: 05/17/2011] [Indexed: 01/16/2023]
Abstract
Earlier, a protein (BMP1, MW-79kDa) had been isolated from Indian toad (Bufo melanostictus) skin aqueous extract possessed anticancer activity against EAC bearing mice (Bhattacharjee et al., 2011). In the present study, the anti-proliferative and apoptogenic activities of BMP1 have been evaluated in leukemic (U937 and K562) and hepatoma (HepG2) cells. BMP1 dose dependently inhibited U937 and K562 cell growth having IC₅₀ values of 49 μg/ml and 30 μg/ml respectively. The anti-proliferative activity of BMP1 was observed in MTT assay, proliferating cell nuclear antigen (PCNA) expression and cell cycle arrest study. Flow-cytometric data revealed that BMP1 arrested cell cycle in U937 and K562 cells at Sub-G1 and G1 phases. The BMP1-induced dose dependent expressions of CDKIs (p21(cip1) and p27(kip1)) and inhibition of CDK2 and PCNA expression in HepG2 cells support the inhibition of cell proliferation due to G1 arrest. BMP1-induced apoptosis analyzed by annexin-V binding study and the DNA fragmentation by comet assay were correlated with the sub-G1 arrest. The parallel induction of bax and p53 expression in HepG2 cells and the up-regulation of caspase 3 and caspase 9 due to BMP1 treatment indicated the involvement of p53-dependent intrinsic pathway of apoptosis. BMP1 was found to be low immunogenic in nature.
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Jorda R, Havlíček L, McNae IW, Walkinshaw MD, Voller J, Šturc A, Navrátilová J, Kuzma M, Mistrík M, Bártek J, Strnad M, Kryštof V. Pyrazolo[4,3-d]pyrimidine Bioisostere of Roscovitine: Evaluation of a Novel Selective Inhibitor of Cyclin-Dependent Kinases with Antiproliferative Activity. J Med Chem 2011; 54:2980-93. [DOI: 10.1021/jm200064p] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Radek Jorda
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Libor Havlíček
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
- Isotope Laboratory, Institute of Experimental Botany ASCR, Videnska 1083, 142 20 Prague, Czech Republic
| | - Iain W. McNae
- Structural Biochemistry Group, University of Edinburgh, Michael Swann Building, King’s Buildings, Edinburgh, EH9 3JR, Scotland
| | - Malcolm D. Walkinshaw
- Structural Biochemistry Group, University of Edinburgh, Michael Swann Building, King’s Buildings, Edinburgh, EH9 3JR, Scotland
| | - Jiří Voller
- Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Department of Growth Regulators, Palacký University, Šlechtitelů 11, Olomouc, CZ-783 71, Czech Republic
| | - Antonín Šturc
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Jana Navrátilová
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Marek Kuzma
- Laboratory of Molecular Structure Characterization, Institute of Microbiology ASCR, Videnska 1083, 142 20 Prague, Czech Republic
| | - Martin Mistrík
- Laboratory of Genome Integrity and Institute of Molecular and Translational Medicine, Palacký University, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Jiří Bártek
- Laboratory of Genome Integrity and Institute of Molecular and Translational Medicine, Palacký University, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Miroslav Strnad
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
| | - Vladimír Kryštof
- Laboratory of Growth Regulators, Faculty of Science, Palacký University and Institute of Experimental Botany ASCR, Šlechtitelů 11, 78371 Olomouc, Czech Republic
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Abaza MSI, Bahman AMA, Al-Attiyah RJ. Roscovitine synergizes with conventional chemo-therapeutic drugs to induce efficient apoptosis of human colorectal cancer cells. World J Gastroenterol 2008; 14:5162-75. [PMID: 18777593 PMCID: PMC2744006 DOI: 10.3748/wjg.14.5162] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
AIM: To examine the ability of cyclin-dependent kinase inhibitor (CDKI) roscovitine (Rosco) to enhance the antitumor effects of conventional chemotherapeutic agents acting by different mechanisms against human colorectal cancer.
METHODS: Human colorectal cancer cells were treated, individually and in combination, with Rosco, taxol, 5-Fluorouracil (5-FU), doxorubicin or vinblastine. The antiproliferative effects and the type of interaction of Rosco with tested chemotherapeutic drugs were determined. Cell cycle alterations were investigated by fluorescence-activated cell sorter FACS analysis. Apoptosis was determined by DNA fragmentation assay.
RESULTS: Rosco inhibited the proliferation of tumor cells in a time- and dose-dependent manner. The efficacies of all tested chemotherapeutic drugs were markedly enhanced 3.0-8.42 × 103 and 130-5.28 × 103 fold in combination with 5 and 10 μg/mL Rosco, respectively. The combination of Rosco and chemotherapeutic drugs inhibited the growth of human colorectal cancer cells in an additive or synergistic fashion, and in a time and dose dependent manner. Rosco induced apoptosis and synergized with tested chemotherapeutic drugs to induce efficient apoptosis in human colorectal cancer cells. Sequential, inverted sequential and simultaneous treatment of cancer cells with combinations of chemotherapeutic drugs and Rosco arrested the growth of human colorectal cancer cells at various phases of the cell cycle as follows: Taxol/Rosco (G2/M- and S-phases), 5-FU/Rosco (S-phase), Dox/Rosco (S-phase) and Vinb/Rosco (G2/M- and S-phases).
CONCLUSION: Since the efficacy of many anticancer drugs depends on their ability to induce apoptotic cell death, modulation of this parameter by cell cycle inhibitors may provide a novel chemo-preventive and chemotherapeutic strategy for human colorectal cancer.
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16
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Gartel AL. Transcriptional inhibitors, p53 and apoptoss. Biochim Biophys Acta Rev Cancer 2008; 1786:83-6. [PMID: 18503775 DOI: 10.1016/j.bbcan.2008.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2008] [Revised: 04/24/2008] [Accepted: 04/27/2008] [Indexed: 02/04/2023]
Abstract
Transcriptional inhibitors (TI) repress global transcription and induce apoptosis. It has been suggested that induction of p53 is one of the hallmarks of global transcriptional repression. Two recent papers suggested that treatment of human cancer cells with TIs, leads to p53-dependent, transcription-independent or p53-dependent, transcription-dependent apoptosis. The latter mechanism is linked to the fact that TIs can be selective in their inhibitory effects thereby permitting transcription of some genes. However, the majority of other published data suggest that these drugs induce p53-independent apoptosis. In this article I discuss the mechanisms of TI-dependent cell death and the potential role of p53 in this process.
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Affiliation(s)
- Andrei L Gartel
- Department of Medicine, University of Illinois at Chicago, Chicago, IL 60612, USA.
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17
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Grigoryev AA, Bulycheva TI, Sheval EV, Kalinina IA, Zatsepina OV. Cytological indicators of overall suppression of protein synthesis revealed by staining with a new monoclonal antibody. ACTA ACUST UNITED AC 2008. [DOI: 10.1134/s1990519x08020144] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Abstract
The p53 tumor suppressor plays a pivotal role in multicellular organism by enforcing benefits of the organism over those of an individual cell. The task of p53 is to control the integrity and correctness of all processes in each individual cell and in the organism as a whole. Information about the state of ongoing events in the cell is gathered through multiple signaling pathways that convey signals modifying activities of p53. Changes in the activities depend on the character of damages or deviations from optimum in processes, and the activity of p53 changes depending on the degree of the aberration, which results in either stimulation of repair processes and protective mechanisms, or the cessation of further cell divisions and the induction of programmed cell death. The strategy of p53 ensures genetic identity of cells and prevents the selection of abnormal cells. By accomplishing these strategic tasks, p53 may use a wide spectrum of activities, such as its ability to function as a transcription factor, by inducing or repressing different genes, or as an enzyme, by acting as an exonuclease during DNA reparation, or as an adaptor or a regulatory protein, intervening into functions of numerous signaling pathways. Loss of function of the p53 gene occurs in virtually every case of cancer, and deficiency in p53 is an unavoidable prerequisite to the development of malignancies. The functions of p53 play substantial roles in many other pathologies as well as in the aging process. This review is focused on strategies of the p53 gene, demonstrating individual mechanisms underlying its functions.
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Affiliation(s)
- P M Chumakov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, 119991 Moscow, Russia.
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19
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Sirri V, Urcuqui-Inchima S, Roussel P, Hernandez-Verdun D. Nucleolus: the fascinating nuclear body. Histochem Cell Biol 2007; 129:13-31. [PMID: 18046571 PMCID: PMC2137947 DOI: 10.1007/s00418-007-0359-6] [Citation(s) in RCA: 295] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2007] [Indexed: 11/30/2022]
Abstract
Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs are synthesized, processed and assembled with ribosomal proteins. RNA polymerase I synthesizes the ribosomal RNAs and this activity is cell cycle regulated. The nucleolus reveals the functional organization of the nucleus in which the compartmentation of the different steps of ribosome biogenesis is observed whereas the nucleolar machineries are in permanent exchange with the nucleoplasm and other nuclear bodies. After mitosis, nucleolar assembly is a time and space regulated process controlled by the cell cycle. In addition, by generating a large volume in the nucleus with apparently no RNA polymerase II activity, the nucleolus creates a domain of retention/sequestration of molecules normally active outside the nucleolus. Viruses interact with the nucleolus and recruit nucleolar proteins to facilitate virus replication. The nucleolus is also a sensor of stress due to the redistribution of the ribosomal proteins in the nucleoplasm by nucleolus disruption. The nucleolus plays several crucial functions in the nucleus: in addition to its function as ribosome factory of the cells it is a multifunctional nuclear domain, and nucleolar activity is linked with several pathologies. Perspectives on the evolution of this research area are proposed.
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Affiliation(s)
- Valentina Sirri
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - Silvio Urcuqui-Inchima
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
- Grupo de Inmunovirología, Biogénesis, Universidad de Antioquia, Calle 62 No. 52-59, Medellin, Colombia
| | - Pascal Roussel
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
| | - Danièle Hernandez-Verdun
- Nuclei and Cell Cycle, CNRS, Université Paris VI, Université Paris VII, Institut Jacques Monod, 2 place Jussieu, 75251 Paris Cedex 05, France
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20
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Cheok CF, Dey A, Lane DP. Cyclin-Dependent Kinase Inhibitors Sensitize Tumor Cells to Nutlin-Induced Apoptosis: a Potent Drug Combination. Mol Cancer Res 2007; 5:1133-45. [DOI: 10.1158/1541-7786.mcr-07-0161] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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21
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Nucleolar targeting of hepatitis delta antigen abolishes its ability to initiate viral antigenomic RNA replication. J Virol 2007; 82:692-9. [PMID: 17989182 DOI: 10.1128/jvi.01155-07] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hepatitis delta virus (HDV) is a small RNA virus that contains one 1.7-kb single-stranded circular RNA of negative polarity. The HDV particle also contains two isoforms of hepatitis delta antigen (HDAg), small (SHDAg) and large HDAg. SHDAg is required for the replication of HDV, which is presumably carried out by host RNA-dependent RNA polymerases. The localization and the HDAg and host RNA polymerase responsible for HDV replication remain important issues to be addressed. In this study, using recombinant SHDAg fused with a heterologous nucleolar localization sequence (NoLS) to confine its subcellular localization in nucleoli, we aimed to study the effect of SHDAg subcellular localization on HDV RNA replication. The initiation of genomic RNA synthesis from antigenomic template was hardly detectable when SHDAg was fused with the NoLS motif and localized mainly in nucleoli. In contrast, the initiation of antigenomic RNA synthesis was not affected. Drug treatment to release a SHDAg-NoLS mutant from nucleoli could partially restore the replication of HDV genomic RNA from antigenomic RNA. This also recovered the cointeraction between SHDAg and RNA polymerase II. These data strongly suggest that nuclear polymerase (RNA polymerase II) is involved in the synthesis of genomic RNA and that the synthesis of antigenomic RNA can occur in nucleoli. Our results support the idea that the replication of HDV genomic RNA or antigenomic RNA is likely to be carried out by different machineries in different subcellular localizations.
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22
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Gomes A, Giri B, Kole L, Saha A, Debnath A, Gomes A. A crystalline compound (BM-ANF1) from the Indian toad (Bufo melanostictus, Schneider) skin extract, induced antiproliferation and apoptosis in leukemic and hepatoma cell line involving cell cycle proteins. Toxicon 2007; 50:835-49. [PMID: 17692879 DOI: 10.1016/j.toxicon.2007.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 06/17/2007] [Accepted: 06/18/2007] [Indexed: 10/23/2022]
Abstract
In our earlier communication, it was reported that Indian toad (Bufo melanostictus) skin extract (TSE) possesses antiproliferative and apoptogenic activity in U937 and K562 cells [Giri et al., 2006. Antiproliferative, cytotoxic and apoptogenic activity of Indian toad (Bufo melanostictus, Schneider) skin extract in U937 and K562 cells. Toxicon 48 (4), 388-400]. In the present study, a compound (BM-ANF1) has been isolated from the TSE by alumina gel column chromatography, crystallized and evaluated for its antiproliferative and apoptogenic activity in U937, K562 and HepG2 cells. BM-ANF1 produced dose-dependent inhibition of U937, K562 and HepG2 cell growth. The antiproliferative activity was reflected by the MTT assay and demonstrated by the reduced expression of proliferative cell nuclear antigen (PCNA). Flow-cytometric analysis showed that BM-ANF1 arrested the cell cycle at G1 phase and enhanced annexin-V binding in U937 and K562 cells. Scanning electron microscopic and fluorescent microscopic analysis of U937 and K562 cells revealed the apoptogenic nature of the compound. Alkaline comet assay showed that BM-ANF1 produced DNA fragmentation. The dose-dependent expression of caspase 3 indicated that the apoptogenic properties of BM-ANF1 were mediated through the activation of downstream effector nucleases in the cancer cells. The increased expression of p53 and moderate expression of p21(Cip1)/p27(Kip1) due to BM-ANF1 treatment in HepG2 cells supported that the apoptogenic activity of BM-ANF1 was mediated through p53 tumor-suppressor gene expression followed by the expression of p21(Cip1) and p27(Kip1) and it was likely to be linked with cell cycle arrest at G1 phase in cancer cells. From the present study, it may be suggested that the crystalline compound, BM-ANF1, was antiproliferative and apoptogenic in human leukemic and hepatoma cells.
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MESH Headings
- Animals
- Antineoplastic Agents/chemistry
- Antineoplastic Agents/pharmacology
- Apoptosis/drug effects
- Bufonidae/physiology
- Carcinoma, Hepatocellular/drug therapy
- Carcinoma, Hepatocellular/metabolism
- Carcinoma, Hepatocellular/pathology
- Cell Cycle Proteins/metabolism
- Cell Line, Tumor
- Cell Proliferation/drug effects
- Comet Assay
- Crystallization
- Dose-Response Relationship, Drug
- Drug Screening Assays, Antitumor
- Gene Expression Regulation, Neoplastic/drug effects
- Humans
- K562 Cells
- Lymphoma, Large B-Cell, Diffuse/drug therapy
- Lymphoma, Large B-Cell, Diffuse/metabolism
- Lymphoma, Large B-Cell, Diffuse/pathology
- Monocytes/drug effects
- Monocytes/pathology
- Skin/chemistry
- Tissue Extracts/chemistry
- Tissue Extracts/pharmacology
- U937 Cells
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Affiliation(s)
- Antony Gomes
- Laboratory of Toxinology and Experimental Pharmacodynamics, Department of Physiology, University of Calcutta, 92, APC Road, Kolkata 700 009, India.
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23
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Pfeuty B, Kaneko K. Minimal requirements for robust cell size control in eukaryotic cells. Phys Biol 2007; 4:194-204. [DOI: 10.1088/1478-3975/4/3/006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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24
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Galons H, Bettayeb K, Meijer L. (R)-Roscovitine (CYC202, Seliciclib). ENZYME INHIBITORS SERIES 2006. [DOI: 10.1201/9781420005400.ch9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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25
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Hirose H, Sakuma N, Kaji N, Suhara T, Sekijima M, Nojima T, Miyakoshi J. Phosphorylation and gene expression of p53 are not affected in human cells exposed to 2.1425 GHz band CW or W-CDMA modulated radiation allocated to mobile radio base stations. Bioelectromagnetics 2006; 27:494-504. [PMID: 16715525 DOI: 10.1002/bem.20238] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A large-scale in vitro study focusing on low-level radiofrequency (RF) fields from mobile radio base stations employing the International Mobile Telecommunication 2000 (IMT-2000) cellular system was conducted to test the hypothesis that modulated RF fields induce apoptosis or other cellular stress response that activate p53 or the p53-signaling pathway. First, we evaluated the response of human cells to microwave exposure at a specific absorption rate (SAR) of 80 mW/kg, which corresponds to the limit of the average whole-body SAR for general public exposure defined as a basic restriction by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. Second, we investigated whether continuous wave (CW) and wideband code division multiple access (W-CDMA) modulated signal RF fields at 2.1425 GHz induced apoptosis or any signs of stress. Human glioblastoma A172 cells were exposed to W-CDMA radiation at SARs of 80, 250, and 800 mW/kg, and CW radiation at 80 mW/kg for 24 or 48 h. Human IMR-90 fibroblasts from fetal lungs were exposed to both W-CDMA and CW radiation at a SAR of 80 mW/kg for 28 h. Under the RF field exposure conditions described above, no significant differences in the percentage of apoptotic cells were observed between the test groups exposed to RF signals and the sham-exposed negative controls, as evaluated by the Annexin V affinity assay. No significant differences in expression levels of phosphorylated p53 at serine 15 or total p53 were observed between the test groups and the negative controls by the bead-based multiplex assay. Moreover, microarray hybridization and real-time RT-PCR analysis showed no noticeable differences in gene expression of the subsequent downstream targets of p53 signaling involved in apoptosis between the test groups and the negative controls. Our results confirm that exposure to low-level RF signals up to 800 mW/kg does not induce p53-dependent apoptosis, DNA damage, or other stress response in human cells.
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Affiliation(s)
- H Hirose
- Research Division for Advanced Technology, Kashima Laboratory, Mitsubishi Chemical Safety Institute Ltd., Kamisu, Japan.
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26
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Hernandez-Verdun D. The nucleolus: a model for the organization of nuclear functions. Histochem Cell Biol 2006; 126:135-48. [PMID: 16835752 DOI: 10.1007/s00418-006-0212-3] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/07/2006] [Indexed: 10/24/2022]
Abstract
Nucleoli are the prominent contrasted structures of the cell nucleus. In the nucleolus, ribosomal RNAs (rRNAs) are synthesized, processed and assembled with ribosomal proteins. The size and organization of the nucleolus are directly related to ribosome production. The organization of the nucleolus reveals the functional compartmentation of the nucleolar machineries that depends on nucleolar activity. When this activity is blocked, disrupted or impossible, the nucleolar proteins have the capacity to interact independently of the processing activity. In addition, nucleoli are dynamic structures in which nucleolar proteins rapidly associate and dissociate with nucleolar components in continuous exchanges with the nucleoplasm. At the time of nucleolar assembly, the processing machineries are recruited in a regulated manner in time and space, controlled by different kinases and form intermediate structures, the prenucleolar bodies. The participation of stable pre-rRNAs in nucleolar assembly was demonstrated after mitosis and during development but this is an intriguing observation since the role of these pre-rRNAs is presently unknown. A brief report on the nucleolus and diseases is proposed as well as of nucleolar functions different from ribosome biogenesis.
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Affiliation(s)
- Danièle Hernandez-Verdun
- Nuclei and Cell Cycle, Institut Jacques Monod, CNRS, Université Paris VI, Université Paris VII, 2 place Jussieu, 75251 Paris Cedex 05, France.
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27
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Louvet E, Junéra HR, Berthuy I, Hernandez-Verdun D. Compartmentation of the nucleolar processing proteins in the granular component is a CK2-driven process. Mol Biol Cell 2006; 17:2537-46. [PMID: 16540521 PMCID: PMC1474808 DOI: 10.1091/mbc.e05-10-0923] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
To analyze the compartmentation of nucleolar protein complexes, the mechanisms controlling targeting of nucleolar processing proteins onto rRNA transcription sites has been investigated. We studied the reversible disconnection of transcripts and processing proteins using digitonin-permeabilized cells in assays capable of promoting nucleolar reorganization. The assays show that the dynamics of nucleolar reformation is ATP/GTP-dependent, sensitive to temperature, and CK2-driven. We further demonstrate the role of CK2 on the rRNA-processing protein B23. Mutation of the major CK2 site on B23 induces reorganization of nucleolar components that separate from each other. This was confirmed in assays using extracts containing B23 mutated in the CK2-binding sites. We propose that phosphorylation controls the compartmentation of the rRNA-processing proteins and that CK2 is involved in this process.
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Affiliation(s)
- Emilie Louvet
- Institut Jacques Monod, Centre National de la Recherche Scientifique, University Paris VI and Paris VII, 75251 Paris Cedex 05, France
| | - Henriette Roberte Junéra
- Institut Jacques Monod, Centre National de la Recherche Scientifique, University Paris VI and Paris VII, 75251 Paris Cedex 05, France
| | - Isabelle Berthuy
- Institut Jacques Monod, Centre National de la Recherche Scientifique, University Paris VI and Paris VII, 75251 Paris Cedex 05, France
| | - Danièle Hernandez-Verdun
- Institut Jacques Monod, Centre National de la Recherche Scientifique, University Paris VI and Paris VII, 75251 Paris Cedex 05, France
- Address correspondence to: D. Hernandez-Verdun (
)
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28
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Wesierska-Gadek J, Schreiner T, Gueorguieva M, Ranftler C. Phenol red reduces ROSC mediated cell cycle arrest and apoptosis in human MCF-7 cells. J Cell Biochem 2006; 98:1367-79. [PMID: 16741967 DOI: 10.1002/jcb.20960] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
We reported recently that roscovitine (ROSC), a selective cyclin-dependent kinase (CDK) inhibitor, arrested human MCF-7 breast cancer cells in G2 phase of the cell cycle and concomitantly induced apoptosis. On the other hand, ROSC-induced G1 arrest observed by another group has not been accompanied by apoptosis. Therefore, we decided to prove to which extent components of tissue culture media could affect the primary action of ROSC. For this purpose we compared the efficacy of the ROSC treatment on MCF-7 cells cultivated in medium with and without phenol red. The kinetics of MCF-7 cell proliferation strongly depended on the presence of phenol red that has been recognized previously as a weak estrogen. Exposure of MCF-7 cells cultivated in phenol red-deprived medium to ROSC resulted in a strong G2 arrest and apoptosis. However, the anti-proliferative and pro-apoptotic action of ROSC was strongly diminished in cells maintained in medium containing phenol red. The ratio of the G2 cell population after 12 h ROSC was reduced by approximately 20% in the latter and correlated with the lack of CDK2 inactivation. Moreover, the kinetics of ROSC-induced apoptosis was delayed in the presence of phenol red. These results clearly evidence that the efficacy of the therapy of ER-positive breast cancers by CDK inhibitors is diminished in the presence of estrogen-mimicking compounds and indicate that phytoestrogens and xenoestrogens could interfere with the therapy. Therefore, the exposure of cancer patients to the estrogen mimics should be avoided at least during chemotherapy by CDK inhibitors.
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Affiliation(s)
- Józefa Wesierska-Gadek
- Department of Medicine I, Division: Institute of Cancer Research, Cell Cycle Regulation Group, Vienna Medical University, Vienna, Austria.
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29
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Wesierska-Gadek J, Schmid G. Dual action of the inhibitors of cyclin-dependent kinases: targeting of the cell-cycle progression and activation of wild-type p53 protein. Expert Opin Investig Drugs 2005; 15:23-38. [PMID: 16370931 DOI: 10.1517/13543784.15.1.23] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The inhibition of cyclin-dependent kinases (CDKs) represents a novel approach to the therapy of human malignancies. Already in clinical trials, recently developed CDK inhibitors very efficiently target the rapidly proliferating cancer cells and inhibit their cell-cycle progression. Interestingly, some CDK inhibitors additionally affect the stability and activity of the tumour-suppressor protein p53, thereby enhancing their antiproliferative action towards cancer cells. Considering the fact that the p53 protein is mutated or inactivated in approximately 50% of all human cancers, the efficacy of CDK inhibitor therapy could differ between cancer cells depending on their p53 status. Moreover, recent reports demonstrating that some cancer cells can proliferate despite CDK2 inhibition questioned the central role of CDK2 in the cell-cycle control and suitability of CDK2 as a therapeutic target; however, the p53 activation that is mediated by CDK inhibitors could be essential for the efficacy of CDK inhibitors in therapy of CDK2-independent cancers. Furthermore, there is also reason to believe that CDK2 inhibitors could be used for another purpose, to protect normal cells from the effects of chemotherapy.
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Affiliation(s)
- Józefa Wesierska-Gadek
- Division Institute of Cancer Research, Dept. of Medicine I, Cell Cycle Regulation Group, Medical University of Vienna, Borschkegasse 8 a, A-1090 Vienna, Austria.
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30
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Abstract
The nucleolus, a large nuclear domain, is the ribosome factory of the cells. Ribosomal RNAs are synthesized, processed and assembled with ribosomal proteins in the nucleolus, and the ribosome subunits are then transported to the cytoplasm. In this review, the structural organization of the nucleolus and the dynamics of the nucleolar proteins are discussed in an attempt to link both information. By electron microscopy, three main nucleolar components corresponding to different steps of ribosome biogenesis are identified and the nucleolar organization reflects its activity. Time-lapse videomicroscopy and fluorescent recovery after photobleaching (FRAP) demonstrate that mobility of GFP-tagged nucleolar proteins is slower in the nucleolus than in the nucleoplasm. Fluorescent recovery rates change with inhibition of transcription, decreased temperature and depletion of ATP, indicating that recovery is correlated with cell activity. At the exit of mitosis, the nucleolar processing machinery is first concentrated in prenucleolar bodies (PNBs). The dynamics of the PNBs suggests a steady state favoring residence of processing factors that are then released in a control- and time-dependent manner. Time-lapse analysis of fluorescence resonance energy transfer demonstrates that processing complexes are formed in PNBs. Finally, the nucleolus appears at the center of several trafficking pathways in the nucleus.
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Affiliation(s)
- Danièle Hernandez-Verdun
- Nuclei and Cell Cycle, Institut Jacques Monod, CNRS, Université Paris VI et Paris VII, 2 place Jussieu, 75251, Paris, Cedex 05, France.
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31
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David-Pfeuty T. The flexible evolutionary anchorage-dependent Pardee's restriction point of mammalian cells: how its deregulation may lead to cancer. Biochim Biophys Acta Rev Cancer 2005; 1765:38-66. [PMID: 16219425 DOI: 10.1016/j.bbcan.2005.08.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Revised: 08/24/2005] [Accepted: 08/26/2005] [Indexed: 12/12/2022]
Abstract
Living cells oscillate between the two states of quiescence and division that stand poles apart in terms of energy requirements, macromolecular composition and structural organization and in which they fulfill dichotomous activities. Division is a highly dynamic and energy-consuming process that needs be carefully orchestrated to ensure the faithful transmission of the mother genotype to daughter cells. Quiescence is a low-energy state in which a cell may still have to struggle hard to maintain its homeostasis in the face of adversity while waiting sometimes for long periods before finding a propitious niche to reproduce. Thus, the perpetuation of single cells rests upon their ability to elaborate robust quiescent and dividing states. This led yeast and mammalian cells to evolve rigorous Start [L.H. Hartwell, J. Culotti, J. Pringle, B.J. Reid, Genetic control of the cell division cycle in yeast, Science 183 (1974) 46-51] and restriction (R) points [A.B. Pardee, A restriction point for control of normal animal cell proliferation, Proc. Natl. Acad. Sci. U. S. A. 71 (1974) 1286-1290], respectively, that reduce deadly interferences between the two states by enforcing their temporal insulation though still enabling a rapid transition from one to the other upon an unpredictable change in their environment. The constitutive cells of multi-celled organisms are extremely sensitive in addition to the nature of their adhering support that fluctuates depending on developmental stage and tissue specificity. Metazoan evolution has entailed, therefore, the need for exceedingly flexible anchorage-dependent R points empowered to assist cells in switching between quiescence and division at various times, places and conditions in the same organism. Programmed cell death may have evolved concurrently in specific contexts unfit for the operation of a stringent R point that increase the risk of deadly interferences between the two states (as it happens notably during development). But, because of their innate flexibility, anchorage-dependent R points have also the ability to readily adjust to a changing structural context so as to give mutated cells a chance to reproduce, thereby encouraging tumor genesis. The Rb and p53 proteins, which are regulated by the two products of the Ink4a-Arf locus [C.J. Sherr, The INK4a/ARF network in tumor suppression, Nat. Rev., Mol. Cell Biol. 2 (2001) 731-737], govern separable though interconnected pathways that cooperate to restrain cyclin D- and cyclin E-dependent kinases from precipitating untimely R point transit. The expression levels of the Ink4a and Arf proteins are especially sensitive to changes in cellular shape and adhesion that entirely remodel at the time when cells shift between quiescence and division. The Arf proteins further display an extremely high translational sensitivity and can activate the p53 pathway to delay R point transit, but, only when released from the nucleolus, 'an organelle formed by the act of building a ribosome' [T. Mélèse, Z. Xue, The nucleolus: an organelle formed by the act of building a ribosome, Curr. Opin. Cell Biol. 7 (1995) 319-324]. In this way, the Ink4a/Rb and Arf/p53 pathways emerge as key regulators of anchorage-dependent R point transit in mammalian cells and their deregulation is, indeed, a rule in human cancers. Thus, by selecting the nucleolus to mitigate cell cycle control by the Arf proteins, mammalian cells succeeded in forging a highly flexible R point enabling them to match cell division with a growth rate imposed by factors controlling nucleolar assembling, such as nutrients and adhesion. It is noteworthy that nutrient control of critical size at Start in budding yeast has been shown recently to be governed by a nucleolar protein interaction network [P. Jorgensen, J.L. Nishikawa, B.-J. Breitkreutz, M. Tyers, Systematic identification of pathways that couple cell growth and division in yeast, Science 297 (2002) 395-400].
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Affiliation(s)
- Thérèse David-Pfeuty
- UMR 146 du CNRS, Institut Curie-Recherche, Bâtiment 110, Centre Universitaire, 91405 Orsay, France.
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MacCallum DE, Melville J, Frame S, Watt K, Anderson S, Gianella-Borradori A, Lane DP, Green SR. Seliciclib (CYC202, R-Roscovitine) Induces Cell Death in Multiple Myeloma Cells by Inhibition of RNA Polymerase II–Dependent Transcription and Down-regulation of Mcl-1. Cancer Res 2005; 65:5399-407. [PMID: 15958589 DOI: 10.1158/0008-5472.can-05-0233] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Seliciclib (CYC202, R-roscovitine) is a cyclin-dependent kinase (CDK) inhibitor that competes for the ATP binding site on the kinase. It has greatest activity against CDK2/cyclin E, CDK7/cyclin H, and CDK9/cyclin T. Seliciclib induces apoptosis from all phases of the cell cycle in tumor cell lines, reduces tumor growth in xenografts in nude mice and is currently in phase II clinical trials. This study investigated the mechanism of cell death in multiple myeloma cells treated with seliciclib. In myeloma cells treated in vitro, seliciclib induced rapid dephosphorylation of the carboxyl-terminal domain of the large subunit of RNA polymerase II. Phosphorylation at these sites is crucial for RNA polymerase II-dependent transcription. Inhibition of transcription would be predicted to exert its greatest effect on gene products where both mRNA and protein have short half-lives, resulting in rapid decline of the protein levels. One such gene product is the antiapoptotic factor Mcl-1, crucial for the survival of a range of cell types including multiple myeloma. As hypothesized, following the inhibition of RNA polymerase II phosphorylation, seliciclib caused rapid Mcl-1 down-regulation, which preceded the induction of apoptosis. The importance of Mcl-1 was confirmed by short interfering RNA, demonstrating that reducing Mcl-1 levels alone was sufficient to induce apoptosis. These results suggest that seliciclib causes myeloma cell death by disrupting the balance between cell survival and apoptosis through the inhibition of transcription and down-regulation of Mcl-1. This study provides the scientific rationale for the clinical development of seliciclib for the treatment of multiple myeloma.
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Affiliation(s)
- David E MacCallum
- Cyclacel Ltd., Dundee Technopole, James Lindsay Place, Dundee, United Kingdom.
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Węsierska-Gądek J, Gueorguieva M, Horky M. Roscovitine-induced up-regulation of p53AIP1 protein precedes the onset of apoptosis in human MCF-7 breast cancer cells. Mol Cancer Ther 2005. [DOI: 10.1158/1535-7163.113.4.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
We reported recently that roscovitine arrested human MCF-7 cancer cells at G2-M phase of the cell cycle and concomitantly induced apoptosis. After roscovitine treatment, the level of wild-type p53 protein strongly increased and p53 was accumulated in the nucleus. Here, we raised the question of which pathway would be involved in roscovitine-induced apoptosis in MCF-7 cells, which are known to be caspase-3-deficient, and whether roscovitine-mediated activation of p53 protein might positively affect the execution of cell death. Roscovitine induced a depolarization of mitochondrial potential beginning at 6 hours posttreatment as evidenced by changes in J-aggregate formation and release of the mitochondrial proteins cytochrome c and apoptosis-inducing factor. Interestingly, roscovitine stimulated a site-specific phosphorylation of wild-type p53 protein in a time-dependent manner. p53 protein was specifically phosphorylated at Ser46. P-Ser46-activated wild-type p53 tumor suppressor up-regulated p53AIP1 protein, its downstream target known to mediate the depolarization of mitochondria. The onset of phosphorylation of p53 at Ser46 preceded the up-regulation of p53AIP1 protein and the depolarization of mitochondrial potential. We compared the kinetics of roscovitine-mediated p53 activation between caspase-3-deficient parental MCF-7 cells and cells reconstituted with caspase-3. The kinetics and the extent of p53 protein activation in caspase-3-proficient cells differed from those observed in caspase-3-deficient parental cells. Remarkably, roscovitine failed to induce phosphorylation at Ser46 in caspase-3-reconstituted MCF-7 cells. Our results indicate that, depending on the status of caspase-3 in MCF-7 cells, different apoptotic pathways were initialized.
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Affiliation(s)
- Józefa Węsierska-Gądek
- 1Cell Cycle Regulation Group, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria and
- 2Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Marieta Gueorguieva
- 1Cell Cycle Regulation Group, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria and
- 2Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Marcel Horky
- 1Cell Cycle Regulation Group, Institute of Cancer Research, Medical University of Vienna, Vienna, Austria and
- 2Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
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Louvet E, Junéra HR, Le Panse S, Hernandez-Verdun D. Dynamics and compartmentation of the nucleolar processing machinery. Exp Cell Res 2004; 304:457-70. [PMID: 15748891 DOI: 10.1016/j.yexcr.2004.11.018] [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] [Received: 08/27/2004] [Revised: 11/08/2004] [Accepted: 11/10/2004] [Indexed: 11/17/2022]
Abstract
In active nucleoli, machineries involved in the biogenesis of ribosomal RNAs (rRNAs) are compartmentalized. The late rRNA processing proteins are localized in the granular component (GC). Here we investigate the behavior of these proteins when production of 28S is impaired and when this blockage is reversed. The 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) provokes dispersion of rDNA clusters and we demonstrate that DRB induces disconnection of the late rRNA processing proteins from the transcription sites. These processing proteins are still associated in independent masses without detectable 28S rRNA, indicating that compartmentation of the late rRNA processing machinery is not necessarily linked to processing activity. Removing DRB reverses this disconnection and promotes rRNA processing. Nucleolar reformation occurs in two successive steps, dynamic recruitment to transcription sites of the processing proteins, followed by rDNA compaction. We demonstrate that both steps are sensitive to temperature, suggesting an energy-dependent process. Traffic of processing proteins analyzed by fluorescence recovery after photobleaching is similar in masses disconnected from transcription sites and in the granular component of the active nucleolus. This suggests that protein dynamics and interactions, and not only their processing activity, determine compartmentation of the nucleolar machineries.
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MESH Headings
- Active Transport, Cell Nucleus/physiology
- Cell Compartmentation/drug effects
- Cell Compartmentation/physiology
- Cell Nucleolus/drug effects
- Cell Nucleolus/metabolism
- Cell Nucleolus/ultrastructure
- Dichlororibofuranosylbenzimidazole/pharmacology
- HeLa Cells
- Humans
- Microscopy, Electron, Transmission
- Nonlinear Dynamics
- Nuclear Proteins/drug effects
- Nuclear Proteins/metabolism
- Nucleic Acid Synthesis Inhibitors/pharmacology
- Protein Transport/physiology
- RNA, Ribosomal/biosynthesis
- RNA, Ribosomal, 28S/drug effects
- RNA, Ribosomal, 28S/metabolism
- Temperature
- Transcription, Genetic/drug effects
- Transcription, Genetic/physiology
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Affiliation(s)
- Emilie Louvet
- Institut Jacques Monod, CNRS, University Paris VI and Paris VII, 2 place Jussieu, 75251 Paris Cedex 05, France
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35
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Hernandez-Verdun D, Louvet E. [The nucleolus: structure, functions, amd associated diseases]. Med Sci (Paris) 2004; 20:37-44. [PMID: 14770362 DOI: 10.1051/medsci/200420137] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
In eukaryotes, the nucleolus is the ribosome factory. The nucleolus is a very active large nuclear domain resulting from the equilibrium between level of ribosomal gene transcription, efficiency of rRNA processing and transport of the ribosomal subunits (40S and 60S) towards the cytoplasm. The ribosome production is regulated and is linked with cell growth and cell proliferation. The ribosome production is stopped during mitosis but the nucleolar machineries are inherited in daughter cells and the nucleolar reassembly is a very early event at the exit of mitosis. The nucleolus is also a multifunctional domain involved in nuclear architecture and specific interaction with some nuclear bodies. Finally, several human diseases appear to result from mutations of nucleolar proteins.
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Affiliation(s)
- Danièle Hernandez-Verdun
- Institut Jacques Monod, Cnrs, Université Paris VI et Paris VII, 2, place Jussieu, 75251 Paris 05, France.
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Bernstein KA, Baserga SJ. The small subunit processome is required for cell cycle progression at G1. Mol Biol Cell 2004; 15:5038-46. [PMID: 15356263 PMCID: PMC524768 DOI: 10.1091/mbc.e04-06-0515] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Without ribosome biogenesis, translation of mRNA into protein ceases and cellular growth stops. We asked whether ribosome biogenesis is cell cycle regulated in the yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe, and we determined that it is not regulated in the same manner as in metazoan cells. We therefore turned our attention to cellular sensors that relay cell size information via ribosome biogenesis. Our results indicate that the small subunit (SSU) processome, a complex consisting of 40 proteins and the U3 small nucleolar RNA necessary for ribosome biogenesis, is not mitotically regulated. Furthermore, Nan1/Utp17, an SSU processome protein, does not provide a link between ribosome biogenesis and cell growth. However, when individual SSU processome proteins are depleted, cells arrest in the G1 phase of the cell cycle. This arrest was further supported by the lack of staining for proteins expressed in post-G1. Similarly, synchronized cells depleted of SSU processome proteins did not enter G2. This suggests that when ribosomes are no longer made, the cells stall in the G1. Therefore, yeast cells must grow to a critical size, which is dependent upon having a sufficient number of ribosomes during the G1 phase of the cell cycle, before cell division can occur.
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Affiliation(s)
- Kara A Bernstein
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
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37
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O'Hagan HM, Ljungman M. Nuclear accumulation of p53 following inhibition of transcription is not due to diminished levels of MDM2. Oncogene 2004; 23:5505-12. [PMID: 15094782 DOI: 10.1038/sj.onc.1207709] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A common mechanism by which the tumor suppressor p53 accumulates in the nucleus following cellular stress is through the attenuation of its interaction with MDM2, a protein involved in the nuclear export and degradation of p53. This is accomplished by induced modifications of p53, MDM2 or both. We have previously found that the kinase and mRNA synthesis inhibitor DRB (5,6-dichloro-1-b-D-ribofuranosylbenzimidazole) induces the nuclear accumulation of p53 without concomitant phosphorylation of the ser15 site of p53, which is thought to be a modification important for the attenuation of p53-MDM2 interaction. It has been proposed that the mechanism by which p53 accumulates following blockage of transcription involves the downregulation of MDM2 expression. In this study, we tested this hypothesis and found that after DRB treatment, p53 accumulated despite the fact that MDM2 levels remained high in human cells. Furthermore, over expression of MDM2 did not prevent the accumulation of p53 following DRB treatment. In, addition, p53 accumulating in the nucleus after DRB treatment was able to interact with MDM2 and was ubiquitylated. These findings suggest that blockage of transcription induce the nuclear accumulation of p53 without breaking the p53-MDM2 regulation loop.
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Affiliation(s)
- Heather M O'Hagan
- Program in Molecular and Cellular Biology, Department of Radiation Oncology, Division of Radiation and Cancer Biology, University of Michigan Medical School, Ann Arbor, MI 48109-0936, USA
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38
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Cheng RYS, Hockman T, Crawford E, Anderson LM, Shiao YH. Epigenetic and gene expression changes related to transgenerational carcinogenesis. Mol Carcinog 2004; 40:1-11. [PMID: 15108325 DOI: 10.1002/mc.20022] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Transgenerational carcinogenesis refers to transmission of cancer risk to the untreated progeny of parents exposed to carcinogens before mating. Accumulated evidence suggests that the mechanism of this process is epigenetic, and might involve hormonal and gene expression changes in offspring. To begin to test this hypothesis, we utilized a mouse model (NIH Swiss) in which exposure of fathers to Cr(III) chloride 2 wk before mating can alter incidence of neoplastic and nonneoplastic changes in offspring tissues. Utilizing a MS-RDA approach, we found that the sperm of these fathers had a significantly higher percentage of undermethylated copies of the 45S ribosomal RNA gene (rRNA); this finding was confirmed by bisulfite sequencing. Because gene methylation is a known mechanism of expression control in germ cells, and ribosomal RNA levels have been linked to cancer, these findings are consistent with the hypothesis. Secondly, we observed that offspring of Cr(III)-treated fathers were significantly heavier than controls, and had higher levels of serum T3. Possible effects of T3 levels on gene expression in the offspring were examined by microarray analysis of cDNAs from liver. A total of 58 genes, including 25 named genes, had expression ratios that correlated significantly with serum T3 ratios at P </= 0.001. Some of these genes have potential roles in growth and/or tumor suppression. These results also support the hypothesis of an epigenetic and/or gene expression-based mechanism for transgenerational carcinogenesis. Published 2004 Wiley-Liss, Inc.
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Affiliation(s)
- Robert Y-S Cheng
- Laboratory of Comparative Carcinogenesis, National Cancer Institute at Frederick, Frederick, Maryland 21702, USA
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39
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Abstract
Recent research suggests that the nucleolus communicates with the p53 regulatory system and acts as a stress sensor. Cellular stress causes nucleolar disruption, triggering the release of regulatory factors to the nucleoplasm. These factors, especially ARF (alternative reading frame), inhibit the degradation of p53, thereby facilitating its intracellular accumulation.
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Affiliation(s)
- Mark O J Olson
- Department of Biochemistry, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS 39216, USA.
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40
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Rubbi CP, Milner J. Disruption of the nucleolus mediates stabilization of p53 in response to DNA damage and other stresses. EMBO J 2004; 22:6068-77. [PMID: 14609953 PMCID: PMC275437 DOI: 10.1093/emboj/cdg579] [Citation(s) in RCA: 614] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
p53 protects against cancer through its capacity to induce cell cycle arrest or apoptosis under a large variety of cellular stresses. It is not known how such diversity of signals can be integrated by a single molecule. However, the literature reveals that a common denominator in all p53-inducing stresses is nucleolar disruption. We thus postulated that the impairment of nucleolar function might stabilize p53 by preventing its degradation. Using micropore irradiation, we demonstrate that large amounts of nuclear DNA damage fail to stabilize p53 unless the nucleolus is also disrupted. Forcing nucleolar disruption by anti-upstream binding factor (UBF) microinjection (in the absence of DNA damage) also causes p53 stabilization. We propose that the nucleolus is a stress sensor responsible for maintenance of low levels of p53, which are automatically elevated as soon as nucleolar function is impaired in response to stress. Our model integrates all known p53-inducing agents and also explains cell cycle-related variations in p53 levels which correlate with established phases of nucleolar assembly/disassembly through the cell cycle.
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Affiliation(s)
- Carlos P Rubbi
- YCR P53 Research Group, Department of Biology, University of York, York YO10 5DD, UK.
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41
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Wojciechowski J, Horky M, Gueorguieva M, Węsierska-Gądek J. Rapid onset of nucleolar disintegration preceding cell cycle arrest in roscovitine-induced apoptosis of human MCF-7 breast cancer cells. Int J Cancer 2003; 106:486-495. [PMID: 12845642 DOI: 10.1002/ijc.11290] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The aim of our study was to explore the antiproliferative and pro-apoptotic action of roscovitine (ROSC) on human breast cancer MCF-7 cells. We examined the effect of ROSC on cell proliferation, cell cycle progression, nucleolar morphology, posttranslational modifications of histones as well as on induction of apoptosis. The effects of ROSC on the argyrophilic nucleolar organizer regions (AgNORs) and nucleolar RNA of MCF-7 cells were marked: ROSC treatment changed the pattern of AgNORs in a time-dependent manner. The disintegration of nucleoli manifested by increasing number of nucleolar fragments already began at 6 hr posttreatment. This was accompanied by a redistribution of the nucleolin from the nucleolus beginning after 6 hr and preceded a decrease of histone acetylation and phosphorylation. Inhibition of DNA synthesis and accumulation of G(2)/M-arrested cells starting 6 hr posttreatment coincided with a strong increase of the p53 level and with an appearance of a few cells committed to undergo apoptosis. However, all these changes preceded the main wave of apoptosis, which occurred after 24 hr ROSC treatment as assessed by determination of the frequency of Annexin binding, activation of caspases as well as of DNA fragmentation. Onset of PARP-1 cleavage detected by immunoblotting and by immunohistochemistry 6 hr or 9 hr posttreatment, respectively, preceded for a few hours the DNA fragmentation detected in situ by TUNEL assay. Reconstitution of MCF-7 cells with caspase-3 did not change the kinetics of ROSC-induced apoptosis. Our results show that disintegration of nucleoli is an early marker of ROSC-induced changes. Cell cycle arrest precedes the main wave of apoptosis.
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Affiliation(s)
- Jacek Wojciechowski
- Cell Cycle Regulation Group, Institute of Cancer Research, University of Vienna, Vienna, Austria
| | - Marcel Horky
- Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - Marieta Gueorguieva
- Cell Cycle Regulation Group, Institute of Cancer Research, University of Vienna, Vienna, Austria
| | - Józefa Węsierska-Gądek
- Cell Cycle Regulation Group, Institute of Cancer Research, University of Vienna, Vienna, Austria
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42
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Takahashi N, Yanagida M, Fujiyama S, Hayano T, Isobe T. Proteomic snapshot analyses of preribosomal ribonucleoprotein complexes formed at various stages of ribosome biogenesis in yeast and mammalian cells. MASS SPECTROMETRY REVIEWS 2003; 22:287-317. [PMID: 12949916 DOI: 10.1002/mas.10057] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Proteomic technologies powered by advancements in mass spectrometry and bioinformatics and coupled with accumulated genome sequence data allow a comprehensive study of cell function through large-scale and systematic protein identifications of protein constituents of the cell and tissues, as well as of multi-protein complexes that carry out many cellular function in a higher-order network in the cell. One of the most extensively analyzed cellular functions by proteomics is the production of ribosome, the protein-synthesis machinery, in the nucle(ol)us--the main site of ribosome biogenesis. The use of tagged proteins as affinity bait, coupled with mass spectrometric identification, enabled us to isolate synthetic intermediates of ribosomes that might represent snapshots of nascent ribosomes at particular stages of ribosome biogenesis and to identify their constituents--some of which showed dynamic changes for association with the intermediates at various stages of ribosome biogenesis. In this review, in conjunction with the results from yeast cells, our proteomic approach to analyze ribosome biogenesis in mammalian cells is described.
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Affiliation(s)
- Nobuhiro Takahashi
- Department of Applied Biological Science, United Graduate School of Agriculture, Tokyo University of Agriculture & Technology, 3-5-8 Saiwai-cho, Fuchu-shi, Tokyo 1838509, Japan.
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43
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Constantinou C, Bushell M, Jeffrey IW, Tilleray V, West M, Frost V, Hensold J, Clemens MJ. p53-induced inhibition of protein synthesis is independent of apoptosis. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3122-32. [PMID: 12869187 DOI: 10.1046/j.1432-1033.2003.03687.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Activation of a temperature-sensitive form of p53 in murine erythroleukaemia cells results in a rapid impairment of protein synthesis that precedes inhibition of cell proliferation and loss of cell viability by several hours. The inhibition of translation is associated with specific cleavages of polypeptide chain initiation factors eIF4GI and eIF4B, a phenomenon previously observed in cells induced to undergo apoptosis in response to other stimuli. Although caspase activity is enhanced in the cells in which p53 is activated, both the effects on translation and the cleavages of the initiation factors are completely resistant to inhibition of caspase activity. Moreover, exposure of the cells to a combination of the caspase inhibitor z-VAD.FMK and the survival factor erythropoietin prevents p53-induced cell death but does not reverse the inhibition of protein synthesis. We conclude that the p53-regulated cleavages of eIF4GI and eIF4B, as well as the overall inhibition of protein synthesis, are caspase-independent events that can be dissociated from the induction of apoptosis per se.
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Affiliation(s)
- Constantina Constantinou
- Translational Control Group, Department of Basic Medical Sciences, St George's Hospital Medical School, Cranmer Terrace, London, UK
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44
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David-Pfeuty T, Nouvian-Dooghe Y. Human p14(Arf): an exquisite sensor of morphological changes and of short-lived perturbations in cell cycle and in nucleolar function. Oncogene 2002; 21:6779-90. [PMID: 12360404 DOI: 10.1038/sj.onc.1205871] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2002] [Revised: 07/08/2002] [Accepted: 07/15/2002] [Indexed: 12/19/2022]
Abstract
The human Ink4a/Arf tumor suppressor locus encodes two distinct products: p16(Ink4a) which prevents phosphorylation and inactivation of the retinoblastoma protein and, p14(Arf), a nucleolar protein which activates the function of the tumor suppressor p53 protein in the nucleoplasm in response to oncogenic stimulation through an as yet ill-defined mechanism. Here we show that the level of endogenous p14(Arf) and its balance between the nucleolus and the nucleoplasm in HeLa cells are exquisitely sensitive to changes in cell morphology and to short-lived perturbations in cell cycle and in nucleolar function such as those induced by the cyclin-dependent kinase inhibitor, roscovitine, and the casein kinase II and RNA synthesis inhibitor, DRB. Most remarkably, whereas p14(Arf) predominantly concentrates in the nucleolus of interphase cells and transiently disappears between metaphase and early G1 under normal growth conditions, it massively and reversibly accumulates in the nucleoplasm of postmitotic and S-phase cells upon short-term treatment with roscovitine and, at a lesser extent, DRB. In line with the fact that the nuclear level of p53 reaches a peak between mid-G1 and the G1/S border in p53-expressor cells which lack Arf expression, these results provide a clue that, in p53+/Arf+ cells, Arf proteins might serve both to speed and to amplify p53-mediated responses in conditions and cell cycle periods in which the mechanisms involved in p53 stabilization and activation are not fully operational. They further suggest that human endogenous p14(Arf) might activate p53 pathways in physiologic situations by acting inside the nucleoplasm, especially when normal cell cycle progression and nucleolar function are compromised.
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Affiliation(s)
- Thérèse David-Pfeuty
- UMR 146 du CNRS, Institut Curie-Recherche, Bâtiment 110, Centre Universitaire, 91405 Orsay Cédex, France.
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45
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Horton LE, Bushell M, Barth-Baus D, Tilleray VJ, Clemens MJ, Hensold JO. p53 activation results in rapid dephosphorylation of the eIF4E-binding protein 4E-BP1, inhibition of ribosomal protein S6 kinase and inhibition of translation initiation. Oncogene 2002; 21:5325-34. [PMID: 12149653 DOI: 10.1038/sj.onc.1205662] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2002] [Revised: 05/07/2002] [Accepted: 05/10/2002] [Indexed: 11/09/2022]
Abstract
p53 is an important regulator of cell cycle progression and apoptosis, and inactivation of p53 is associated with tumorigenesis. Although p53 exerts many of its effects through regulation of transcription, this protein is also found in association with ribosomes and several mRNAs have been identified that are translationally controlled in a p53-dependent manner. We have utilized murine erythroleukemic cells that express a temperature-sensitive p53 protein to determine whether p53 also functions at the level of translation. The data presented here demonstrate that p53 causes a rapid decrease in translation initiation. Analysis of several potential mechanisms for regulating protein synthesis shows that p53 has selective effects on the phosphorylation of the eIF4E-binding protein, 4E-BP1, and the activity of the p70 ribosomal protein S6 kinase. These data provide evidence that modulation of translational activity constitutes a further mechanism by which the growth inhibitory effects of p53 may be mediated.
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Affiliation(s)
- Lynn E Horton
- The Department of Medicine, University/Ireland Cancer Center, Case Western Reserve University School of Medicine, 10900 Euclid Ave.-BRB 333, Cleveland, Ohio, OH 44106-4937, USA
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