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Savinkova LK, Sharypova EB, Kolchanov NA. On the Role of TATA Boxes and TATA-Binding Protein in Arabidopsis thaliana. PLANTS (BASEL, SWITZERLAND) 2023; 12:1000. [PMID: 36903861 PMCID: PMC10005294 DOI: 10.3390/plants12051000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 01/13/2023] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
For transcription initiation by RNA polymerase II (Pol II), all eukaryotes require assembly of basal transcription machinery on the core promoter, a region located approximately in the locus spanning a transcription start site (-50; +50 bp). Although Pol II is a complex multi-subunit enzyme conserved among all eukaryotes, it cannot initiate transcription without the participation of many other proteins. Transcription initiation on TATA-containing promoters requires the assembly of the preinitiation complex; this process is triggered by an interaction of TATA-binding protein (TBP, a component of the general transcription factor TFIID (transcription factor II D)) with a TATA box. The interaction of TBP with various TATA boxes in plants, in particular Arabidopsis thaliana, has hardly been investigated, except for a few early studies that addressed the role of a TATA box and substitutions in it in plant transcription systems. This is despite the fact that the interaction of TBP with TATA boxes and their variants can be used to regulate transcription. In this review, we examine the roles of some general transcription factors in the assembly of the basal transcription complex, as well as functions of TATA boxes of the model plant A. thaliana. We review examples showing not only the involvement of TATA boxes in the initiation of transcription machinery assembly but also their indirect participation in plant adaptation to environmental conditions in responses to light and other phenomena. Examples of an influence of the expression levels of A. thaliana TBP1 and TBP2 on morphological traits of the plants are also examined. We summarize available functional data on these two early players that trigger the assembly of transcription machinery. This information will deepen the understanding of the mechanisms underlying transcription by Pol II in plants and will help to utilize the functions of the interaction of TBP with TATA boxes in practice.
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High Throughput miRNA Screening Identifies miR-574-3p Hyperproductive Effect in CHO Cells. Biomolecules 2021; 11:biom11081125. [PMID: 34439791 PMCID: PMC8392531 DOI: 10.3390/biom11081125] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 07/11/2021] [Accepted: 07/23/2021] [Indexed: 12/21/2022] Open
Abstract
CHO is the cell line of choice for the manufacturing of many complex biotherapeutics. The constant upgrading of cell productivity is needed to meet the growing demand for these life-saving drugs. Manipulation of small non-coding RNAs—miRNAs—is a good alternative to a single gene knockdown approach due to their post-transcriptional regulation of entire cellular pathways without posing translational burden to the production cell. In this study, we performed a high-throughput screening of 2042-human miRNAs and identified several candidates able to increase cell-specific and overall production of Erythropoietin and Etanercept in CHO cells. Some of these human miRNAs have not been found in Chinese hamster cells and yet were still effective in them. We identified miR-574-3p as being able, when overexpressed in CHO cells, to improve overall productivity of Erythropoietin and Etanercept titers from 1.3 to up to 2-fold. In addition, we validated several targets of miR-574-3p and identified p300 as a main target of miR-574-3p in CHO cells. Furthermore, we demonstrated that stable CHO cell overexpressing miRNAs from endogenous CHO pri-miRNA sequences outperform the cells with human pri-miRNA sequences. Our findings highlight the importance of flanking genomic sequences, and their secondary structure features, on pri-miRNA processing offering a novel, cost-effective and fast strategy as a valuable tool for efficient miRNAs engineering in CHO cells.
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Frosi Y, Inoue K, Ramlan SR, Lane DP, Watanabe T, Brown CJ. Simultaneous measurement of p53:Mdm2 and p53:Mdm4 protein-protein interactions in whole cells using fluorescence labelled foci. Sci Rep 2019; 9:17933. [PMID: 31784573 PMCID: PMC6884555 DOI: 10.1038/s41598-019-54123-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 11/08/2019] [Indexed: 12/26/2022] Open
Abstract
In this report we describe the development of a Fluorescent Protein-Protein Interaction-visualization (FLUOPPI) to enable the simultaneous measurement of both Mdm2:p53 and Mdm4:p53 interactions in order to assess the relative efficiencies of mimetic molecules of the p53 peptide helix against both PPIs. Mdm2 and Mdm4 overexpression frequently leads to the inactivation of non-mutated p53 in human cancers, via inhibition of its transcriptional activity, enhancing its degradation by the proteasome or by preventing its nuclear import. Development of inhibitors to disrupt the binding of one or both of these protein interactions have been the subject of intensive pharmaceutical development for anti-cancer therapies. Using the bimodal FLUOPPI system we have characterised compounds that were either monospecific for Mdm2 or bispecific for both Mdm2 and Mdm4. We have also demonstrated that the FLUOPPI assay can reliably differentiate between specific and non-specific disruption of these protein complexes via accurate assessment and normalization to the cell population under measurement. We envision that this methodology will increase the efficiency of identifying compounds that are either specific against a single PPI from a closely related family of interactions or compounds that interact across multiple related PPI pairs, depending on which is more desirable.
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Affiliation(s)
- Y Frosi
- p53 Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore, 138648, Singapore
| | - K Inoue
- R&D Division, Medical & Biological Laboratories, Co., Ltd., 1063-103 Terasawaoka, Ina, Nagano, 396-0002, Japan
| | - Siti Radhiah Ramlan
- p53 Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore, 138648, Singapore
| | - D P Lane
- p53 Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore, 138648, Singapore
| | - T Watanabe
- R&D Division, Medical & Biological Laboratories, Co., Ltd., 1063-103 Terasawaoka, Ina, Nagano, 396-0002, Japan.
| | - C J Brown
- p53 Laboratory, A*STAR (Agency for Science, Technology and Research), 8A Biomedical Grove, #06-04/05, Neuros/Immunos, Singapore, 138648, Singapore.
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Chan C, Thurnherr T, Wang J, Gallart-Palau X, Sze SK, Rozen S, Lee CG. Global re-wiring of p53 transcription regulation by the hepatitis B virus X protein. Mol Oncol 2016; 10:1183-95. [PMID: 27302019 DOI: 10.1016/j.molonc.2016.05.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 05/16/2016] [Accepted: 05/17/2016] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND The tumour suppressor p53 is a central player in transcription regulation and cell fate determination. By interacting with p53 and altering its sequence-specific binding to the response elements, the hepatitis B virus X protein (HBx) was reported to re-direct p53 regulation of some genes. RESULTS Coupling massively parallel deep sequencing with p53 chromatin immunoprecipitation, we demonstrate that HBx modulates global p53 site selection and that this was strongly influenced by altered interaction with transcription co-factors/co-regulators as well as post-translational modifications. Specifically, HBx attenuated p53-TBP-RB1 transcription complex recruitment and interaction and this was associated with hyper-phosphorylation of p53 at serine 315 by HBx. Concurrently, HBx enhanced p53 DNA occupancy to other response elements either alone by displacing specific transcription factors such as CEBPB and NFkB1, or in complex with distinct interacting co-factors Sp1, JUN and E2F1. Importantly, re-wiring of p53 transcription regulation by HBx was linked to the deregulation of genes involved in cell proliferation and death, suggesting a role of HBx in errant cell fate determination mediated by altered p53 site selection of target genes. CONCLUSIONS Our study thus presents first evidence of global modes of p53 transcription alteration by HBx and provides new insights to understand and potentially curtail the viral oncoprotein.
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Affiliation(s)
- Cheryl Chan
- Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, Singapore 169610, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Thomas Thurnherr
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore; Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Jingbo Wang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore
| | - Xavier Gallart-Palau
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Siu Kwan Sze
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | - Steve Rozen
- Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Caroline G Lee
- Division of Medical Sciences, Humphrey Oei Institute of Cancer Research, National Cancer Centre Singapore, Singapore 169610, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore; Duke-NUS Graduate Medical School, Singapore 169857, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117597, Singapore.
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Adikesavan AK, Karmakar S, Pardo P, Wang L, Liu S, Li W, Smith CL. Activation of p53 transcriptional activity by SMRT: a histone deacetylase 3-independent function of a transcriptional corepressor. Mol Cell Biol 2014; 34:1246-61. [PMID: 24449765 PMCID: PMC3993559 DOI: 10.1128/mcb.01216-13] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The silencing mediator of retinoic acid and thyroid hormone receptors (SMRT) is an established histone deacetylase 3 (HDAC3)-dependent transcriptional corepressor. Microarray analyses of MCF-7 cells transfected with control or SMRT small interfering RNA revealed SMRT regulation of genes involved in DNA damage responses, and the levels of the DNA damage marker γH2AX as well as poly(ADP-ribose) polymerase cleavage were elevated in SMRT-depleted cells treated with doxorubicin. A number of these genes are established p53 targets. SMRT knockdown decreased the activity of two p53-dependent reporter genes as well as the expression of p53 target genes, such as CDKN1A (which encodes p21). SMRT bound directly to p53 and was recruited to p53 binding sites within the p21 promoter. Depletion of GPS2 and TBL1, components of the SMRT corepressor complex, but not histone deacetylase 3 (HDAC3) decreased p21-luciferase activity. p53 bound to the SMRT deacetylase activation domain (DAD), which mediates HDAC3 binding and activation, and HDAC3 could attenuate p53 binding to the DAD region of SMRT. Moreover, an HDAC3 binding-deficient SMRT DAD mutant coactivated p53 transcriptional activity. Collectively, these data highlight a biological role for SMRT in mediating DNA damage responses and suggest a model where p53 binding to the DAD limits HDAC3 interaction with this coregulator, thereby facilitating SMRT coactivation of p53-dependent gene expression.
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Affiliation(s)
| | - Sudipan Karmakar
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Patricia Pardo
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Liguo Wang
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
| | - Shuang Liu
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
| | - Wei Li
- Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas, USA
| | - Carolyn L. Smith
- Molecular and Cellular Biology, Baylor College of Medicine, Houston, Texas, USA
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Rodova M, Jayini R, Singasani R, Chipps E, Islam MR. CMV promoter is repressed by p53 and activated by JNK pathway. Plasmid 2013; 69:223-30. [PMID: 23376463 DOI: 10.1016/j.plasmid.2013.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 12/21/2012] [Accepted: 01/11/2013] [Indexed: 11/18/2022]
Abstract
Viral promoters are widely utilized in commercial and customized vectors to drive expression of genes of interest including reporter, effector and transfection control, because of their high transcription efficiency in a variety of primary and transformed cell lines. However, we observed altered rate of transcription for these promoters under conditions such as presence of an effector protein. These variations in viral promoter driven expressions can potentially lead to incorrect conclusion, especially in comparative and quantitative experiments. We found significantly reduced viral promoter activity in cells overexpressing tumor suppressor protein p53, whereas markedly induced transcription in cells overexpressing MAP/ERK kinase kinase 1 (Mekk 1). Using deletion constructs generated from the CMV promoter, we found the transcription reduction by p53 is possibly mediated through the TATA motif present in proximal CMV promoter. The activation of the CMV promoter by Mekk 1, on the other hand, is attributed to the proximal CRE binding site in the promoter. These findings may be of interest to investigators who use CMV (or other viral) promoter driven vectors for either comparative or quantitative gene expression, or effect on promoter activity.
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Affiliation(s)
- Marianna Rodova
- Laboratory of Biochemistry, Garrett-Strong Science Building 3100, Northwest Missouri State University, Maryville, MO 64468, USA
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TNFα induced FOXP3–NFκB interaction dampens the tumor suppressor role of FOXP3 in gastric cancer cells. Biochem Biophys Res Commun 2013. [DOI: 10.1016/j.bbrc.2012.11.039] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Quaas M, Müller GA, Engeland K. p53 can repress transcription of cell cycle genes through a p21(WAF1/CIP1)-dependent switch from MMB to DREAM protein complex binding at CHR promoter elements. Cell Cycle 2012. [PMID: 23187802 PMCID: PMC3562311 DOI: 10.4161/cc.22917] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The tumor suppressor p53 plays an important role in cell cycle arrest by downregulating transcription. Many genes repressed by p53 code for proteins with functions in G₂/M. A large portion of these genes is controlled by cell cycle-dependent elements (CDE) and cell cycle genes homology regions (CHR) in their promoters. Cyclin B2 is an example of such a gene, with a function at the transition from G₂ to mitosis. We find that p53-dependent downregulation of cyclin B2 promoter activity is dependent on an intact CHR element. In the presence of high levels of p53 or p21WAF1/CIP1, protein binding to the CHR switches from MMB to DREAM complex by shifting MuvB core-associated proteins from B-Myb to E2F4/DP1/p130. The results suggest a model for p53-dependent transcriptional repression by which p53 directly activates p21WAF1/CIP1. The inhibitor then prevents further phosphorylation of p130 by cyclin-dependent kinases. The presence of hypophosphorylated pocket proteins shifts the equilibrium for complex formation from MMB to DREAM. In the case of promoters that do not hold CDE or E2F elements, binding of DREAM and MMB solely relies on a CHR site. Thus, p53 can repress target genes indirectly through CHR elements.
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Affiliation(s)
- Marianne Quaas
- Department of Molecular Oncology, Medical School, University of Leipzig, Leipzig, Germany
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Mohareer K, Sahdev S, Hasnain SE. Baculovirus p35 gene is oppositely regulated by P53 and AP-1 like factors in Spodoptera frugiperda. Biochem Biophys Res Commun 2011; 414:688-93. [PMID: 21986530 DOI: 10.1016/j.bbrc.2011.09.133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2011] [Accepted: 09/27/2011] [Indexed: 11/25/2022]
Abstract
Baculovirus p35 belongs to the early class of genes of AcMNPV and requires viral factors like Immediate Early protein-1 for its transcription. To investigate the role of host factors in regulating p35 gene expression, the putative transcription factor binding sites were examined in silico and the role of these factors in influencing the transcription of p35 gene was assessed. We focused our studies on AP-1 and P53-like factors, which are activated under oxidative stress conditions. The AP-1 motif is located at -1401 while P53 motif is at -1912 relative to p35 translation start site. The predicted AP-1 and P53 elements formed specific complexes with Spodoptera frugiperda nuclear extracts. Both AP-1 and P53 motif binding proteins were down regulated as a function of AcMNPV infection in Spodoptera cells. To address the question whether during an oxidative outburst, the p35 transcription is enhanced; we investigated the role of these oxidative stress induced host transcription factors in influencing p35 gene transcription. Reporter assays revealed that AP-1 element enhances the transcription of p35 by a factor of two. Interestingly, P53 element appears to repress the transcription of p35 gene.
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Affiliation(s)
- Krishnaveni Mohareer
- Laboratory of Molecular and Cell Biology, Center for DNA Fingerprinting and Diagnostics, Hyderabad 500001, India
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10
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Wang MJ, Pei DS, Qian GW, Yin XX, Cheng Q, Li LT, Li HZ, Zheng JN. p53 regulates Ki-67 promoter activity through p53- and Sp1-dependent manner in HeLa cells. Tumour Biol 2011; 32:905-12. [PMID: 21611785 DOI: 10.1007/s13277-011-0191-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 05/12/2011] [Indexed: 01/10/2023] Open
Abstract
The expression of the human Ki-67 protein, which is strictly associated with cell proliferation, is regulated by a variety of cellular mediators. In this study, we studied the effects of p53 on Ki-67 promoter in HeLa cells using luciferase reporter assay. The results showed that: (1) p53 inhibited Ki-67 promoter activity in a dose-dependent manner, (2) the p53-binding motifs mediated part of the transcriptional repression of Ki-67 promoter through a sequence-specific interaction with p53, (3) p53 was able to repress the Sp1-stimulated Ki-67 promoter activity, and (4) the Sp1-binding sites were responsible for the p53-mediated transcriptional repression of Ki-67 promoter. In conclusion, p53 inhibited Ki-67 promoter activity via p53- and Sp1-dependent pathways, and the interaction between p53 and Sp1 might be involved in the transcriptional regulatory mechanisms.
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Affiliation(s)
- Mei-Juan Wang
- Jiangsu Key Laboratory of Biological Cancer Therapy, Xuzhou Medical College, 84 West Huai-hai Road, Xuzhou, 221002, Jiangsu, People's Republic of China
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One function--multiple mechanisms: the manifold activities of p53 as a transcriptional repressor. J Biomed Biotechnol 2011; 2011:464916. [PMID: 21436991 PMCID: PMC3062963 DOI: 10.1155/2011/464916] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2010] [Accepted: 01/17/2011] [Indexed: 12/31/2022] Open
Abstract
Maintenance of genome integrity is a dynamic process involving complex regulation systems. Defects in one or more of these pathways could result in cancer. The most important tumor-suppressor is the transcription factor p53, and its functional inactivation is frequently observed in many tumor types. The tumor suppressive function of p53 is mainly attributed to its ability to regulate numerous target genes at the transcriptional level. While the mechanism of transcriptional induction by p53 is well characterized, p53-dependent repression is not understood in detail. Here, we review the manifold mechanisms of p53 as a transcriptional repressor. We classify two different categories of repressed genes based on the underlying mechanism, and novel mechanisms which involve regulation through noncoding RNAs are discussed. The complete elucidation of p53 functions is important for our understanding of its tumor-suppressor activity and, therefore, represents the key for the development of novel therapeutic approaches.
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Patel J, Pathak RR, Mujtaba S. The biology of lysine acetylation integrates transcriptional programming and metabolism. Nutr Metab (Lond) 2011; 8:12. [PMID: 21371315 PMCID: PMC3060110 DOI: 10.1186/1743-7075-8-12] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2010] [Accepted: 03/03/2011] [Indexed: 11/18/2022] Open
Abstract
The biochemical landscape of lysine acetylation has expanded from a small number of proteins in the nucleus to a multitude of proteins in the cytoplasm. Since the first report confirming acetylation of the tumor suppressor protein p53 by a lysine acetyltransferase (KAT), there has been a surge in the identification of new, non-histone targets of KATs. Added to the known substrates of KATs are metabolic enzymes, cytoskeletal proteins, molecular chaperones, ribosomal proteins and nuclear import factors. Emerging studies demonstrate that no fewer than 2000 proteins in any particular cell type may undergo lysine acetylation. As described in this review, our analyses of cellular acetylated proteins using DAVID 6.7 bioinformatics resources have facilitated organization of acetylated proteins into functional clusters integral to cell signaling, the stress response, proteolysis, apoptosis, metabolism, and neuronal development. In addition, these clusters also depict association of acetylated proteins with human diseases. These findings not only support lysine acetylation as a widespread cellular phenomenon, but also impel questions to clarify the underlying molecular and cellular mechanisms governing target selectivity by KATs. Present challenges are to understand the molecular basis for the overlapping roles of KAT-containing co-activators, to differentiate between global versus dynamic acetylation marks, and to elucidate the physiological roles of acetylated proteins in biochemical pathways. In addition to discussing the cellular 'acetylome', a focus of this work is to present the widespread and dynamic nature of lysine acetylation and highlight the nexus that exists between epigenetic-directed transcriptional regulation and metabolism.
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Affiliation(s)
- Jigneshkumar Patel
- Department of Structural and Chemical Biology, Mount Sinai School of Medicine New York, NY 10029 USA.
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13
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Abstract
Inactivation of p53 is critical for the formation of most tumors. Illumination of the key function(s) of p53 protein in protecting cells from becoming cancerous is therefore a worthy goal. Arguably p53's most important function is to act as a transcription factor that directly regulates perhaps several hundred of the cell's RNA polymerase II (RNAP II)-transcribed genes, and indirectly regulates thousands of others. Indeed p53 is the most well studied mammalian transcription factor. The p53 tetramer binds to its response element where it can recruit diverse transcriptional coregulators such as histone modifying enzymes, chromatin remodeling factors, subunits of the mediator complex, and components of general transcription machinery and preinitiation complex (PIC) to modulate RNAPII activity at target loci (Laptenko and Prives 2006). The p53 transcriptional program is regulated in a stimulus-specific fashion (Murray-Zmijewski et al. 2008; Vousden and Prives 2009), whereby distinct subsets of p53 target genes are induced in response to different p53-activating agents, likely allowing cells to tailor their response to different types of stress. How p53 is able to discriminate between these different loci is the subject of intense research. Here, we describe key aspects of the fundamentals of p53-mediated transcriptional regulation and target gene promoter selectivity.
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Affiliation(s)
- Rachel Beckerman
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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14
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TAF6delta orchestrates an apoptotic transcriptome profile and interacts functionally with p53. BMC Mol Biol 2010; 11:10. [PMID: 20096117 PMCID: PMC2827470 DOI: 10.1186/1471-2199-11-10] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Accepted: 01/22/2010] [Indexed: 01/30/2023] Open
Abstract
Background TFIID is a multiprotein complex that plays a pivotal role in the regulation of RNA polymerase II (Pol II) transcription owing to its core promoter recognition and co-activator functions. TAF6 is a core TFIID subunit whose splice variants include the major TAF6α isoform that is ubiquitously expressed, and the inducible TAF6δ. In contrast to TAF6α, TAF6δ is a pro-apoptotic isoform with a 10 amino acid deletion in its histone fold domain that abolishes its interaction with TAF9. TAF6δ expression can dictate life versus death decisions of human cells. Results Here we define the impact of endogenous TAF6δ expression on the global transcriptome landscape. TAF6δ was found to orchestrate a transcription profile that included statistically significant enrichment of genes of apoptotic function. Interestingly, gene expression patterns controlled by TAF6δ share similarities with, but are not equivalent to, those reported to change following TAF9 and/or TAF9b depletion. Finally, because TAF6δ regulates certain p53 target genes, we tested and demonstrated a physical and functional interaction between TAF6δ and p53. Conclusion Together our data define a TAF6δ-driven apoptotic gene expression program and show crosstalk between the p53 and TAF6δ pathways.
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Abstract
The p53 protein is one of the most important tumor suppressor proteins. Normally, the p53 protein is in a latent state. However, when its activity is required, e.g. upon DNA damage, nucleotide depletion or hypoxia, p53 becomes rapidly activated and initiates transcription of pro-apoptotic and cell cycle arrest-inducing target genes. The activity of p53 is regulated both by protein abundance and by post-translational modifications of pre-existing p53 molecules. In the 30 years of p53 research, a plethora of modifications and interaction partners that modulate p53's abundance and activity have been identified and new ones are continuously discovered. This review will summarize our current knowledge on the regulation of p53 abundance and activity.
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Affiliation(s)
- Karen A Boehme
- Forschungszentrum Karlsruhe, Institute of Toxicology and Genetics, Karlsruhe, Germany
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16
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Salah Z, Haupt S, Maoz M, Baraz L, Rotter V, Peretz T, Haupt Y, Bar-Shavit R. p53 controls hPar1 function and expression. Oncogene 2008; 27:6866-74. [DOI: 10.1038/onc.2008.324] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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17
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Hong M, Li W, Wang L, Jiang L, Liu L, Zhao H, Li Q. Identification of a novel transcriptional repressor (HEPIS) that interacts with nsp-10 of SARS coronavirus. Viral Immunol 2008; 21:153-62. [PMID: 18433331 DOI: 10.1089/vim.2007.0108] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A novel gene was previously isolated from a cDNA library of human embryo lung tissue by its encoded protein, which interacts with non-structural protein 10 (nsp-10) of the severe acute respiratory syndrome coronavirus (SARS-CoV). The protein was named human embryo lung cellular protein interacting with SARS-CoV nsp-10 (HEPIS), and it is composed of 147 amino acids with several CK II phosphorylation sites. In the present study, we demonstrated that HEPIS was capable of suppressing chloramphenicol acetyltransferase (CAT) gene expression controlled by different enhancerelements in a transcription assay. HEPIS interacted specifically with the HSP70 TATA sequence, and not with various other enhancer elements in a binding test. Furthermore, we co-immunoprecipitated HEPIS with BTF3, a component of the RNA pol II initiation complex, and observed reduced proliferation of HeLa cells transfected with the HEPIS gene. Taken together, our results suggest that HEPIS may function as a potential transcriptional repressor.
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Affiliation(s)
- Min Hong
- Institute of Medical Biology, Chinese Academy of Medicine Science, Peking Union Medical College, Kunming, China
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18
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Wilhelm E, Pellay FX, Benecke A, Bell B. TAF6delta controls apoptosis and gene expression in the absence of p53. PLoS One 2008; 3:e2721. [PMID: 18628956 PMCID: PMC2444026 DOI: 10.1371/journal.pone.0002721] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 06/18/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Life and death decisions of metazoan cells hinge on the balance between the expression of pro- versus anti-apoptotic gene products. The general RNA polymerase II transcription factor, TFIID, plays a central role in the regulation of gene expression through its core promoter recognition and co-activator functions. The core TFIID subunit TAF6 acts in vitro as an essential co-activator of transcription for the p53 tumor suppressor protein. We previously identified a splice variant of TAF6, termed TAF6delta that can be induced during apoptosis. METHODOLOGY/PRINCIPAL FINDINGS To elucidate the impact of TAF6delta on cell death and gene expression, we have employed modified antisense oligonucleotides to enforce expression of endogenous TAF6delta. The induction of endogenous TAF6delta triggered apoptosis in tumor cell lines, including cells devoid of p53. Microarray experiments revealed that TAF6delta activates gene expression independently of cellular p53 status. CONCLUSIONS Our data define TAF6delta as a pivotal node in a signaling pathway that controls gene expression programs and apoptosis in the absence of p53.
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Affiliation(s)
- Emmanuelle Wilhelm
- RNA Group, Département de microbiologie et d'infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - François-Xavier Pellay
- Institut des Hautes Études Scientifiques and Institut de Recherche Interdisciplinaire – CNRS USR3078 - Université de Lille, Bures sur Yvette, France
| | - Arndt Benecke
- Institut des Hautes Études Scientifiques and Institut de Recherche Interdisciplinaire – CNRS USR3078 - Université de Lille, Bures sur Yvette, France
| | - Brendan Bell
- RNA Group, Département de microbiologie et d'infectiologie, Faculté de médecine et sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
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Bereczki O, Ujfaludi Z, Pardi N, Nagy Z, Tora L, Boros IM, Balint E. TATA binding protein associated factor 3 (TAF3) interacts with p53 and inhibits its function. BMC Mol Biol 2008; 9:57. [PMID: 18549481 PMCID: PMC2441632 DOI: 10.1186/1471-2199-9-57] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 06/12/2008] [Indexed: 01/16/2023] Open
Abstract
Background The tumour suppressor protein p53 is a sequence specific DNA-binding transcription regulator, which exerts its versatile roles in genome protection and apoptosis by affecting the expression of a large number of genes. In an attempt to obtain a better understanding of the mechanisms by which p53 transcription function is regulated, we studied p53 interactions. Results We identified BIP2 (Bric-à-brac interacting protein 2), the fly homolog of TAF3, a histone fold and a plant homeodomain containing subunit of TFIID, as an interacting partner of Drosophila melanogaster p53 (Dmp53). We detected physical interaction between the C terminus of Dmp53 and the central region of TAF3 both in yeast two hybrid assays and in vitro. Interestingly, DmTAF3 can also interact with human p53, and mammalian TAF3 can bind to both Dmp53 and human p53. This evolutionarily conserved interaction is functionally significant, since elevated TAF3 expression severely and selectively inhibits transcription activation by p53 in human cell lines, and it decreases the level of the p53 protein as well. Conclusion We identified TAF3 as an evolutionarily conserved negative regulator of p53 transcription activation function.
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Affiliation(s)
- Orsolya Bereczki
- Department of Biochemistry and Molecular Biology, University of Szeged, Szeged, Hungary.
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20
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Abstract
The p53 protein regulates the transcription of many different genes in response to a wide variety of stress signals. Following DNA damage, p53 regulates key processes, including DNA repair, cell-cycle arrest, senescence and apoptosis, in order to suppress cancer. This Analysis article provides an overview of the current knowledge of p53-regulated genes in these pathways and others, and the mechanisms of their regulation. In addition, we present the most comprehensive list so far of human p53-regulated genes and their experimentally validated, functional binding sites that confer p53 regulation.
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21
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The contribution of transactivation subdomains 1 and 2 to p53-induced gene expression is heterogeneous but not subdomain-specific. Neoplasia 2008; 9:1057-65. [PMID: 18084613 DOI: 10.1593/neo.07688] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2007] [Revised: 09/22/2007] [Accepted: 09/25/2007] [Indexed: 12/14/2022] Open
Abstract
Two adjacent regions within the transactivation domain of p53 are sufficient to support sequence-specific transactivation when fused to a heterologous DNA binding domain. It has been hypothesized that these two subdomains of p53 may contribute to the expression of distinct p53-responsive genes. Here we have used oligonucleotide microarrays to identify transcripts induced by variants of p53 with point mutations within subdomains 1, 2, or 1 and 2 (QS1, QS2, and QS1/QS2, respectively). The expression of 254 transcripts was increased in response to wild-type p53 expression but most of these transcripts were poorly induced by these variants of p53. Strikingly, a number of known p53-regulated transcripts including TNFRSF10B, BAX, BTG2, and POLH were increased to wild-type levels by p53(QS1) and p53(QS2) but not p53(QS1/QS2), indicating that either subdomain 1 or 2 is sufficient for p53-dependent expression of a small subset of p53-responsive genes. Unexpectedly, there was no evidence for p53(QS1)- or p53(QS2)-specific gene expression. Taken together, we found heterogeneity in the requirement for transactivation subdomains 1 and 2 of p53 without any subdomain-specific contribution to p53-induced gene expression.
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22
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Astanehe A, Arenillas D, Wasserman WW, Leung PCK, Dunn SE, Davies BR, Mills GB, Auersperg N. Mechanisms underlying p53 regulation of PIK3CA transcription in ovarian surface epithelium and in ovarian cancer. J Cell Sci 2008; 121:664-74. [PMID: 18270270 DOI: 10.1242/jcs.013029] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Inactivation of the transcription factor and tumor suppressor p53, and overexpression or mutational activation of PIK3CA, which encodes the p110alpha catalytic subunit of phosphatidylinositol-3-kinase (PI3K), are two of the most common deleterious genomic changes in cancer, including in ovarian carcinomas. We investigated molecular mechanisms underlying interactions between these two mediators and their possible roles in ovarian tumorigenesis. We identified two alternate PIK3CA promoters and showed direct binding of and transcriptional inhibition by p53 to one of these promoters. Conditional suppression of functional p53 increased p110alpha transcripts, protein levels and PI3K activity in immortalized, non-tumorigenic ovarian surface epithelial (OSE) cells, the precursors of ovarian carcinoma. Conversely, overexpression of p53 by adenoviral infection and activation of p53 by gamma-irradiation both diminished p110alpha protein levels in normal OSE and ovarian cancer cells. The demonstration that p53 binds directly to the PIK3CA promoter and inhibits its activity identifies a novel mechanism whereby these two mediators regulate cellular functions, and whereby inactivation of p53 and subsequent upregulation of PIK3CA might contribute to the pathophysiology of ovarian cancer.
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Affiliation(s)
- Arezoo Astanehe
- Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, Canada
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23
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Adaptor Protein LAPF Recruits Phosphorylated p53 to Lysosomes and Triggers Lysosomal Destabilization in Apoptosis. Cancer Res 2007; 67:11176-85. [DOI: 10.1158/0008-5472.can-07-2333] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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24
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DNA (cytosine-5)-methyltransferase 1 as a mediator of mutant p53-determined p16ink4A down-regulation. J Biomed Sci 2007; 15:163-8. [DOI: 10.1007/s11373-007-9222-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2007] [Accepted: 11/02/2007] [Indexed: 10/22/2022] Open
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25
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Lee J, Beliakoff J, Sun Z. The novel PIAS-like protein hZimp10 is a transcriptional co-activator of the p53 tumor suppressor. Nucleic Acids Res 2007; 35:4523-34. [PMID: 17584785 PMCID: PMC1935018 DOI: 10.1093/nar/gkm476] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The tumor suppressor, p53, plays critical roles in the cell cycle progression, DNA repair and apoptosis. The PIAS proteins (protein inhibitor of activated STAT) were originally identified as inhibitors of the JAK-STAT pathway. Subsequently, crosstalk between the PIAS proteins and other signaling pathways has been shown to be involved in various cellular processes. Particularly, previous studies have demonstrated that PIAS proteins regulate p53-mediated transcription through sumoylation. hZimp10, also named zmiz1, is a novel PIAS-like protein and functions as a transcriptional co-activator. We recently identified p53 to be an hZimp10 interacting protein in the yeast two-hybrid screen. The interaction between p53 and hZimp10 was confirmed by GST pull-down and co-immunoprecipitation assays. Co-localization of p53 and hZimp10 proteins was also observed within cell nuclei by immunostaining. Moreover, we show that expression of exogenous hZimp10 enhances the transcriptional activity of p53 and knockdown of endogenous hZimp10 reduces the transcriptional activity of p53. Furthermore, using chromatin immunoprecipitation assays, we demonstrate that hZimp10 binds to p53 on the p21 promoter. Finally, p53-mediated transcription is significantly impaired in Zimp10 null embryonic fibroblasts. Taken together, these results provide the first line of evidence to demonstrate a role for Zimp10 in regulating p53 function.
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Affiliation(s)
| | | | - Zijie Sun
- *To whom correspondence should be addressed. +1 650 498 7523+1 650 723 4200
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26
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Giono LE, Manfredi JJ. The p53 tumor suppressor participates in multiple cell cycle checkpoints. J Cell Physiol 2006; 209:13-20. [PMID: 16741928 DOI: 10.1002/jcp.20689] [Citation(s) in RCA: 211] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The process of cell division is highly ordered and regulated. Checkpoints exist to delay progression into the next cell cycle phase only when the previous step is fully completed. The ultimate goal is to guarantee that the two daughter cells inherit a complete and faithful copy of the genome. Checkpoints can become activated due to DNA damage, exogenous stress signals, defects during the replication of DNA, or failure of chromosomes to attach to the mitotic spindle. Abrogation of cell cycle checkpoints can result in death for a unicellular organism or uncontrolled proliferation and tumorigenesis in metazoans (Nyberg et al., 2002). The tumor suppressor p53 plays a critical role in each of these cell cycle checkpoints and is reviewed here.
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Affiliation(s)
- Luciana E Giono
- Department of Oncological Sciences, Mount Sinai School of Medicine, New York, New York 10029, USA
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27
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Zhang DW, Jeang KT, Lee CGL. p53 negatively regulates the expression of FAT10, a gene upregulated in various cancers. Oncogene 2006; 25:2318-27. [PMID: 16501612 DOI: 10.1038/sj.onc.1209220] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
FAT10 is a member of the ubiquitin-like modifier family of proteins and has been implicated to play important roles in antigen presentation, cytokine response, apoptosis and mitosis. We have recently demonstrated the upregulation of FAT10 gene expression in 90% of hepatocellular carcinoma patients. Here, we identified and characterized the promoter of the FAT10 gene to elucidate the mechanism of FAT10 gene expression. Notably, we found that the 5' untranslated region (5'UTR), from the transcription start site to 15 bases before the translational start site, displays significant promoter activity. Regions upstream of the 5'UTR (from +26 to -1997) do not confer any promoter activity. Curiously, FAT10 promoter activity and expression is significantly repressed in KB3-1 and HepG2 cells, which have wild-type p53, than in p53-negative Hep3B cells. The role of p53 in regulating FAT10 expression was evident by the significant downregulation (P<0.05) of FAT10 mRNA expression and promoter activity when wild-type p53 was transfected into p53-null Hep3B cells. Conversely, inhibiting p53 expression through siRNA against p53 significantly enhanced FAT10 expression and promoter activity. p53 was found to bind in vivo to the 5' half consensus sequence of p53-binding site located at the FAT10 promoter. Hence, we propose that FAT10 is a downstream target of p53 and dysregulation of FAT10 expression in p53-defective cells could contribute to carcinogenesis.
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Affiliation(s)
- D W Zhang
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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28
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Yang R, Weber DJ, Carrier F. Post-transcriptional regulation of thioredoxin by the stress inducible heterogenous ribonucleoprotein A18. Nucleic Acids Res 2006; 34:1224-36. [PMID: 16513844 PMCID: PMC1388095 DOI: 10.1093/nar/gkj519] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Thioredoxin (TRX) is a key protein of the cellular redox metabolism, which expression is increased in several tumors especially gastric tumors. Even though ultraviolet (UV) and hypoxia specifically induce TRX, the mechanisms that lead to increased TRX levels are still ill defined. Here, we show that the heterogenous ribonucleoprotein A18 (hnRNP A18) RNA Binding Domain (RBD) and the arginine, glycine (RGG) rich domain can bind TRX 3′-untranslated region (3′-UTR) independently but both domains are required for maximal binding. Immunoprecipitation (IP) of hnRNP A18-mRNAs complexes and co-localization of hnRNP A18 and TRX transcripts on ribosomal fractions confirm the interaction of hnRNP A18 with TRX transcripts in cells. Moreover, down regulation of hnRNP A18 correlates with a significant reduction of TRX protein levels. In addition, hnRNP A18 increases TRX translation and interacts with the eukaryotic Initiation Factor 4G (eIF4G), a component of the general translational machinery. Furthermore, hnRNP A18 phosphorylation by the hypoxia inducible GSK3β increases hnRNP A18 RNA binding activity in vitro and in RKO cells in response to UV radiation. These data support a regulatory role for hnRNP A18 in TRX post-transcriptional expression possibly through a kissing loop model bridging TRX 3′- and 5′-UTRs through eIF4G.
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Affiliation(s)
| | | | - France Carrier
- To whom correspondence should be addressed at Department of Biochemistry and Molecular Biology, University of Maryland School of Medicine, 108 N. Greene St. Baltimore, MD 21201, USA. Tel: +1 410 706 5105; Fax: +1 410 706 8297;
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29
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Baraz L, Haupt Y, Elkin M, Peretz T, Vlodavsky I. Tumor suppressor p53 regulates heparanase gene expression. Oncogene 2006; 25:3939-47. [PMID: 16474844 DOI: 10.1038/sj.onc.1209425] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Mammalian heparanase degrades heparan sulfate, the most prominent polysaccharide of the extracellular matrix. Causal involvement of heparanase in tumor progression is well documented. Little is known, however, about mechanisms that regulate heparanase gene expression. Mutational inactivation of tumor suppressor p53 is the most frequent genetic alteration in human tumors. p53 is a transcription factor that regulates a wide variety of cellular promoters. In this study, we demonstrate that wild-type (wt) p53 binds to heparanase promoter and inhibits its activity, whereas mutant p53 variants failed to exert an inhibitory effect. Moreover, p53-H175R mutant even activated heparanase promoter activity. Elimination or inhibition of p53 in several cell types resulted in a significant increase in heparanase gene expression and enzymatic activity. Trichostatin A abolished the inhibitory effect of wt p53, suggesting the involvement of histone deacetylation in negative regulation of the heparanase promoter. Altogether, our results indicate that the heparanase gene is regulated by p53 under normal conditions, while mutational inactivation of p53 during cancer development leads to induction of heparanase expression, providing a possible explanation for the frequent increase of heparanase levels observed in the course of tumorigenesis.
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Affiliation(s)
- L Baraz
- Department of Oncology, Hadassah-University Medical Center, Jerusalem, Israel
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30
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Moumen A, Masterson P, O'Connor MJ, Jackson SP. hnRNP K: An HDM2 Target and Transcriptional Coactivator of p53 in Response to DNA Damage. Cell 2005; 123:1065-78. [PMID: 16360036 DOI: 10.1016/j.cell.2005.09.032] [Citation(s) in RCA: 265] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Revised: 08/10/2005] [Accepted: 09/07/2005] [Indexed: 02/04/2023]
Abstract
In response to DNA damage, mammalian cells trigger the p53-dependent transcriptional induction of factors that regulate DNA repair, cell-cycle progression, or cell survival. Through differential proteomics, we identify heterogeneous nuclear ribonucleoprotein K (hnRNP K) as being rapidly induced by DNA damage in a manner that requires the DNA-damage signaling kinases ATM or ATR. Induction of hnRNP K ensues through the inhibition of its ubiquitin-dependent proteasomal degradation mediated by the ubiquitin E3 ligase HDM2/MDM2. Strikingly, hnRNP K depletion abrogates transcriptional induction of p53 target genes and causes defects in DNA-damage-induced cell-cycle-checkpoint arrests. Furthermore, in response to DNA damage, p53 and hnRNP K are recruited to the promoters of p53-responsive genes in a mutually dependent manner. These findings establish hnRNP K as a new HDM2 target and show that, by serving as a cofactor for p53, hnRNP K plays key roles in coordinating transcriptional responses to DNA damage.
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Affiliation(s)
- Abdeladim Moumen
- The Wellcome Trust and Cancer Research UK Gurdon Institute and Department of Zoology, Cambridge University, Tennis Court Road, Cambridge CB2 1QN, United Kingdom
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31
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Gridasova AA, Henry RW. The p53 tumor suppressor protein represses human snRNA gene transcription by RNA polymerases II and III independently of sequence-specific DNA binding. Mol Cell Biol 2005; 25:3247-60. [PMID: 15798209 PMCID: PMC1069601 DOI: 10.1128/mcb.25.8.3247-3260.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Human U1 and U6 snRNA genes are transcribed by RNA polymerases II and III, respectively. While the p53 tumor suppressor protein is a general repressor of RNA polymerase III transcription, whether p53 regulates snRNA gene transcription by RNA polymerase II is uncertain. The data presented herein indicate that p53 is an effective repressor of snRNA gene transcription by both polymerases. Both U1 and U6 transcription in vitro is repressed by recombinant p53, and endogenous p53 occupancy at these promoters is stimulated by UV light. In response to UV light, U1 and U6 transcription is strongly repressed. Human U1 genes, but not U6 genes, contain a high-affinity p53 response element located within the core promoter region. Nonetheless, this element is not required for p53 repression and mutant p53 molecules that do not bind DNA can maintain repression, suggesting a reliance on protein interactions for p53 promoter recruitment. Recruitment may be mediated by the general transcription factors TATA-box binding protein and snRNA-activating protein complex, which interact well with p53 and function for both RNA polymerase II and III transcription.
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Affiliation(s)
- Anastasia A Gridasova
- Department of Biochemistry & Molecular Biology, Michigan State University, East Lansing, MI 48824.
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32
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Wei X, Xu H, Kufe D. Human MUC1 oncoprotein regulates p53-responsive gene transcription in the genotoxic stress response. Cancer Cell 2005; 7:167-78. [PMID: 15710329 DOI: 10.1016/j.ccr.2005.01.008] [Citation(s) in RCA: 195] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2004] [Revised: 11/30/2004] [Accepted: 01/19/2005] [Indexed: 01/19/2023]
Abstract
The MUC1 oncoprotein is aberrantly overexpressed by most human carcinomas. The present work demonstrates that MUC1 associates with the p53 tumor suppressor, and that this interaction is increased by genotoxic stress. The MUC1 cytoplasmic domain binds directly to p53 regulatory domain. Chromatin immunoprecipitation assays demonstrate that MUC1 coprecipitates with p53 on the p53-responsive elements of the p21 gene promoter and coactivates p21 gene transcription. Conversely, MUC1 attenuates activation of Bax transcription. In concert with these results, MUC1 promotes selection of the p53-dependent growth arrest response and suppresses the p53-dependent apoptotic response to DNA damage. These findings indicate that MUC1 regulates p53-responsive genes and thereby cell fate in the genotoxic stress response.
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Affiliation(s)
- Xiaolong Wei
- Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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Kaldis P. The N-terminal peptide of the Kaposi's sarcoma-associated herpesvirus (KSHV)-cyclin determines substrate specificity. J Biol Chem 2005; 280:11165-74. [PMID: 15664993 DOI: 10.1074/jbc.m408887200] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Cyclin-dependent kinases (Cdks) are activated by cyclin binding and phosphorylation by the Cdk-activating kinase (CAK). Activation of Cdk6 by the D-type cyclins requires phosphorylation of Cdk6 by CAK on threonine 177. In contrast, Cdk6 is activated by the Kaposi's sarcoma-associated herpesvirus (KSHV)-cyclin in the absence and presence of CAK phosphorylation. The activity of Cdk6.KSHV-cyclin complexes was investigated here by analyzing mutants of the KSHV-cyclin and Cdk6 in vitro as well as in U2OS cells. Deletion of the N terminus of the KSHV-cyclin affects the substrate specificity indicating that the N terminus is required for phosphorylation of histone H1 but not for other substrates. Mutation of residues in the region 180-200 of the KSHV-cyclin decreases the binding affinity to Cdk6 in U2OS cells but increases the activity of Cdk6.KSHV-cyclin complexes in vitro indicating that low affinity binding of cyclins to the Cdk subunit might favor increased on- or off-rates of Cdk substrates. Expression of high levels of p16(INK4a) in cells leads to the formation of a heterotrimeric complex composed of Cdk6, KSHV-cyclin, and p16(INK4a). Some of the Cdk6 .KSHV-cyclin.p16 complexes were found to be active indicating that there might be different modes of p16 binding to Cdk6.cyclin complexes.
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Affiliation(s)
- Philipp Kaldis
- Mouse Cancer Genetics Program, National Cancer Institute, NCI-Frederick, Frederick, Maryland 21702-1201, USA.
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Zheng G, Yang YC. ZNF76, a Novel Transcriptional Repressor Targeting TATA-binding Protein, Is Modulated by Sumoylation. J Biol Chem 2004; 279:42410-21. [PMID: 15280358 DOI: 10.1074/jbc.m407287200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Direct interaction of positive and negative regulators with the general transcription machinery modulates transcription. The TATA-binding protein (TBP) is one target for transcriptional regulators. In this study, we identified ZNF76 as a novel transcriptional repressor that targets TBP. ZNF76 interacts with TBP through both its N and C termini, and both regions are required for ZNF76 to exert its inhibitory function on p53-mediated transactivation. The inhibitory effect of ZNF76 on p53 activity was demonstrated by reporter assays and endogenous target gene expression. We mapped the TBP-interacting region in the C terminus of ZNF76 to a glutamic acid-rich domain, which acts in a dominant negative manner to enhance p53-mediated transactivation in reporter assays. Mutagenesis study for ZNF76 suggests a correlation between interaction with TBP and effect on p53-mediated transactivation, supporting the conclusion that ZNF76 targets TBP for transcriptional repression. Chromatin immunoprecipitation experiments suggest that ZNF76 prevents TBP from occupying the endogenous p21 promoter. ZNF76 is sumoylated by PIAS1 at lysine 411, which is in the minimal TBP-interacting region. Overexpression of PIAS1 and SUMO-1 abolishes the interaction between ZNF76 and TBP and partially relieves the repressive effect of ZNF76. These results suggest that ZNF76 functions as a transcriptional repressor through its interaction with TBP and that sumoylation modulates its transcriptional repression activity.
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Affiliation(s)
- Gang Zheng
- Department of Pharmacology and Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106, USA
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35
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Wang W, Nahta R, Huper G, Marks JR. TAFII70 Isoform-Specific Growth Suppression Correlates With Its Ability to Complex With the GADD45a Protein. Mol Cancer Res 2004. [DOI: 10.1158/1541-7786.442.2.8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
TAFII70, a member of the basal transcription complex implicated in p53-mediated transcription, is synthesized as several alternately spliced variants. The predominant forms found in normal and neoplastic breast epithelial cells are shown to be 72 kDa (TAFII70) and 78 kDa (TAFII80). Most cancers express higher levels of the TAFII80 isoform, whereas normal breast epithelia express higher levels of the TAFII70 isoform. Expression of TAFII70, but not TAFII80, causes dramatic growth suppression of normal and transformed breast epithelial cell lines in a p53-independent manner. Growth suppression correlates with mitotic inhibition resulting from an increased number of cells in G2. Both isoforms induce expression of the G2 arrest associated gene, GADD45a, but a novel protein-protein interaction was observed between TAFII70 (not TAFII80) and GADD45a, suggesting that this interaction is important for the observed growth arrest phenotype induced by the TAFII70 isoform. GADD45a null cells are not subject to TAFII70 inhibition, further supporting the relevance of this interaction.
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Affiliation(s)
- Wei Wang
- Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Rita Nahta
- Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Gudrun Huper
- Department of Surgery, Duke University Medical Center, Durham, North Carolina
| | - Jeffrey R. Marks
- Department of Surgery, Duke University Medical Center, Durham, North Carolina
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36
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Abstract
p53 is frequently mutated in cancer and as a result is one of the most intensely studied tumour suppressors. Analysis of the primitive forms of p53 found in Caenorhabditis elegans and Drosophila, alongside studies using transgenic mouse models, indicate that the induction of apoptosis is both the most conserved function of p53 and vital for tumour suppression. p53-mediated apoptosis occurs through a combination of mechanisms which include pathways that are both dependent and independent of alterations in gene expression. In response to genotoxic insult, these pathways probably act together, thereby amplifying the apoptotic signal. However, the picture is complicated because the p53 activity is determined by stress type and individual cellular characteristics. The numerous p53 responsive genes that have been identified also provide further means of controlling the actions of p53. The recent discoveries of proteins that interact with p53 and specifically regulate the ability of p53 to trigger apoptosis have provided further mechanistic insights into the role of p53 in inducing cell death. Understanding the molecular basis of the proapoptotic action of p53 can assist in our quest to reintroduce or reactivate p53 in human tumours.
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Affiliation(s)
- Elizabeth A Slee
- Imperial College School of Medicine at St Mary's, Ludwig Institute for Cancer Research, Norfolk Place, London W2 1PG, UK
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Matsui T, Katsuno Y, Inoue T, Fujita F, Joh T, Niida H, Murakami H, Itoh M, Nakanishi M. Negative regulation of Chk2 expression by p53 is dependent on the CCAAT-binding transcription factor NF-Y. J Biol Chem 2004; 279:25093-100. [PMID: 15044452 DOI: 10.1074/jbc.m403232200] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The kinase Chk2 and tumor suppressor p53 participate in an ill defined regulatory interaction in mammalian cells. The abundance of Chk2 mRNA and protein has now been shown to be decreased by the induction of p53 in Saos2 cells. Ionizing radiation also triggered the phosphorylation and subsequent down-regulation of Chk2 in human colorectal HCT116 (p53(+/+)) cancer cells; irradiation of its isogenic mutant HCT116 (p53(-/-)) cells, which lack functional p53, induced Chk2 phosphorylation but not its down-regulation. In addition, HCT116 (p53(+/+)) cells constitutively expressing a dominant negative p53 (V143A) failed to suppress Chk2 expression after irradiation. Reporter gene assays in HCT116 (p53(+/+)) cells revealed that wild-type p53 repressed, whereas a dominant negative p53 mutant increased, the activity of the human Chk2 gene promoter. Mutational analysis showed that a CCAAT box located between nucleotides -152 and -138 of the promoter was responsible for its negative regulation by p53. Electrophoretic mobility shift assays demonstrated that the transcription factor NF-Y binds to this CCAAT sequence. A dominant negative mutant of NF-YA abolished the effect of p53 on Chk2 promoter activity. These results suggest that p53 negatively regulates Chk2 gene transcription through modulation of NF-Y function and that this regulation may be important for reentry of cells into the cell cycle after DNA damage is repaired.
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Affiliation(s)
- Taido Matsui
- Department of Biochemistry and Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan
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38
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Arthur DC, Ghetu AF, Gubbins MJ, Edwards RA, Frost LS, Glover JNM. FinO is an RNA chaperone that facilitates sense-antisense RNA interactions. EMBO J 2004; 22:6346-55. [PMID: 14633993 PMCID: PMC291848 DOI: 10.1093/emboj/cdg607] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The protein FinO represses F-plasmid conjugative transfer by facilitating interactions between the mRNA of the major F-plasmid transcriptional activator, TraJ, and an antisense RNA, FinP. FinO is known to bind stem-loop structures in both FinP and traJ RNAs; however, the mechanism by which FinO facilitates sense-antisense pairing is poorly understood. Here we show that FinO acts as an RNA chaperone to promote strand exchange and duplexing between minimal RNA targets derived from FinP. This strongly suggests that FinO may function to destabilize internal secondary structures within FinP and traJ RNAs that would otherwise act as a kinetic trap to sense-antisense pairing. The energy for FinO-catalyzed base-pair destabilization does not arise from ATP hydrolysis but appears to be supplied directly from FinO RNA binding free energy. An analysis of the activities of mutants that are specifically deficient in strand exchange but not RNA-binding activity demonstrates that strand exchange is essential to the ability of FinO to mediate sense-antisense RNA recognition, and that this function also plays a role in repression of conjugation in vivo.
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Affiliation(s)
- David C Arthur
- Department of Biochemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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39
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Muredda M, Nunoya KI, Burtch-Wright RA, Kurz EU, Cole SPC, Deeley RG. Cloning and Characterization of the Murine and Rat mrp1 Promoter Regions. Mol Pharmacol 2003; 64:1259-69. [PMID: 14573776 DOI: 10.1124/mol.64.5.1259] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The ATP-binding cassette transporter multidrug resistance protein 1 (MRP1) confers resistance to a number of clinically important chemotherapeutic agents. The proximal promoter region of MRP1 is GC-rich and contains binding sites for members of the Sp1 family of trans-acting factors that seem to be important for basal expression. As an approach to searching for other elements that may contribute to expression, we have sequenced and functionally compared the promoters of the murine and rat mrp1 genes with that of the human gene. All three promoters are GC-rich, TATA-less, and CAAT-less. Conservation of sequence between rodent and human promoters is limited to a proximal region of 100 nucleotides containing binding sites for members of the Sp1 family and a putative activator protein-1 element. The 5'-untranslated region (UTR) of human MRP1 contains an insertion of approximately 160 nucleotides comprising a GCC-triplet repeat and a GC-rich tandem repeat that is absent from the rodent sequences. Transient transfection analyses demonstrated that the conserved GC-boxes of all three genes are the major determinants of basal activity. Based on electrophoretic mobility shift assays, each GC-box can be bound by Sp1 or Sp3. Unlike the rodent genes, the human MRP1 5'UTR also binds Sp1 but not Sp3, and the human promoter retains substantial activity even in the absence of the conserved GC-boxes. Finally, we show that the tumor suppressor protein p53 can repress the human and rodent promoters by a mechanism that is independent of the Sp1 elements.
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Affiliation(s)
- Mario Muredda
- Queen's University Cancer Research Institute, Botterell Hall Room A315C, Queen's University, Kingston, Ontario, Canada K7L 3N6
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40
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Chen Z, Manley JL. Core promoter elements and TAFs contribute to the diversity of transcriptional activation in vertebrates. Mol Cell Biol 2003; 23:7350-62. [PMID: 14517303 PMCID: PMC230314 DOI: 10.1128/mcb.23.20.7350-7362.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2003] [Revised: 05/27/2003] [Accepted: 07/07/2003] [Indexed: 11/20/2022] Open
Abstract
Gene-specific transcriptional activation is a multistep process that requires numerous protein factors and DNA elements, including enhancers and the core promoter. To investigate the roles of core promoter elements in transcriptional activation in vertebrates, we examined expression and factor occupancy on representative promoters in chicken DT40 cells containing a conditional TATA binding protein (TBP)-associated factor 9 allele (TAF9). Characterized core elements, including TATA box-flanking regions and the downstream promoter element, were found to play significant roles in determining promoter strength, response to activators, and factor occupancy and recruitment. The requirement for TAF9 was found to be highly promoter specific, and TAF9 dependence and promoter occupancy were not always correlated. We also describe contrasting examples of factor recruitment and activation mechanisms at different promoters, highlighted by the nearly opposite mechanisms utilized by the simian virus 40 enhancer and p53. With the core promoters analyzed, the former functions by facilitating RNA polymerase II (RNAP II) recruitment to a preassembled TBP/TFIIB-containing scaffold and p53 strongly recruits TBP and TFIIB while RNAP II levels remain modest. Taken together, our results illustrate both the important roles of core promoter elements and the remarkable diversity that characterizes transcriptional activation mechanisms in vertebrates.
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Affiliation(s)
- Zheng Chen
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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41
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Iovanna JL. Expression of the stress-associated protein p8 is a requisite for tumor development. INTERNATIONAL JOURNAL OF GASTROINTESTINAL CANCER 2003; 31:89-98. [PMID: 12622419 DOI: 10.1385/ijgc:31:1-3:89] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We identified a new gene, called p8, because its expression was strongly induced during the acute phase of pancreatitis. Further experiments have shown that p8 mRNA is activated in response to several stresses and that its activation is not restricted to pancreatic cells. p8 is a nuclear protein and biochemical and biophysical studies have shown that p8 was very similar in many structural aspects to the HMG proteins, although sharing only low amino acid sequence homology. Also, p8 was found overexpressed in many human cancers. Therefore, we wondered whether the p8-mediated response to cellular stress was necessary for tumor establishment. Subcutaneous or intraperitoneal injections of transformed p8-expressing fibroblasts led to tumor formation in nude mice, but no tumor was observed with transformed p8-deficient cells. Restoring p8 expression in transformed p8-deficient fibroblasts led to tumor formation, demonstrating that p8 expression is crucial for tumor development and suggesting that the stress-response mechanisms governed by p8 are required for tumor establishment.
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Affiliation(s)
- Juan L Iovanna
- Centre de Recherche INSERM, EMI0116, 163 avenue de Luminy, Parc Scientifique et Technologique de Luminy, BP 172, 13009 Marseille, France.
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42
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Crighton D, Woiwode A, Zhang C, Mandavia N, Morton JP, Warnock LJ, Milner J, White RJ, Johnson DL. p53 represses RNA polymerase III transcription by targeting TBP and inhibiting promoter occupancy by TFIIIB. EMBO J 2003; 22:2810-20. [PMID: 12773395 PMCID: PMC156762 DOI: 10.1093/emboj/cdg265] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The tumor suppressor p53 is a transcription factor that controls cellular growth and proliferation. p53 targets include RNA polymerase (pol) III-dependent genes encoding untranslated RNAs such as tRNA and 5S rRNA. These genes are repressed through interaction of p53 with TFIIIB, a TATA-binding protein (TBP)-containing factor. Although many studies have shown that p53 binds to TBP, the significance of this interaction has remained elusive. Here we demonstrate that the TBP-p53 interaction is of functional importance for regulating RNA pol III-transcribed genes. Unlike RNA pol II-dependent promoter repression, overexpressing TBP can reverse inhibition of tRNA gene transcription by p53. p53 does not disrupt the direct interaction between the TFIIIB subunits TBP and Brf1, but prevents the association of Brf1 complexes with TFIIIC2 and RNA pol III. Using chromatin immunoprecipitation assays, we found that TFIIIB occupancy on tRNA genes markedly decreases following p53 induction, whereas binding of TFIIIC2 to these genes is unaffected. Together our results support the idea that p53 represses RNA pol III transcription through direct interactions with TBP, preventing promoter occupancy by TFIIIB.
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Affiliation(s)
- Diane Crighton
- Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ, UK
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43
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Uramoto H, Izumi H, Nagatani G, Ohmori H, Nagasue N, Ise T, Yoshida T, Yasumoto K, Kohno K. Physical interaction of tumour suppressor p53/p73 with CCAAT-binding transcription factor 2 (CTF2) and differential regulation of human high-mobility group 1 (HMG1) gene expression. Biochem J 2003; 371:301-10. [PMID: 12534345 PMCID: PMC1223307 DOI: 10.1042/bj20021646] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2002] [Revised: 01/14/2003] [Accepted: 01/20/2003] [Indexed: 12/27/2022]
Abstract
The CCAAT-binding transcription factor (CTF)/nuclear factor I (NF-I) group of cellular DNA-binding proteins recognizes the sequence GCCAAT and is implicated in eukaryotic transcription, as well as DNA replication. Molecular analysis of human CTF/NF-I cDNA clones revealed multiple mRNA species that contain alternative coding regions, apparently as a result of differential splicing. Expression and functional analysis established that individual gene products can bind to GCCAAT recognition sites and serve as both promoter-selective transcriptional activators and initiation factors for DNA replication. The interaction between CTF2 and p53/p73 was shown to modulate their ability to regulate transcription of their respective target genes. In the present paper, we report that p53 down-regulates the activity of the high mobility group 1 (HMG1) gene promoter, whereas p73alpha up-regulates the activity of this promoter. Furthermore, CTF2 transactivates p53-induced p21 promoter activity, but inhibits p73alpha-induced p21 promoter activity. Using deletion mutants, we found that the DNA-binding domains of both p53 and p73alpha are required for physical interaction with CTF2 via the regions between amino acid residues 161 and 223, and 228 and 312 respectively. CTF2 enhances the DNA-binding activity of p53 and inhibits the DNA-binding activity of p73alpha. These results provide novel information on the functional interplay between CTF2 and p53/p73 as important determinants of their function in cell proliferation, apoptosis, DNA repair and cisplatin resistance.
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Affiliation(s)
- Hidetaka Uramoto
- Department of Molecular Biology, University of Occupational and Environmental Health, 1-1 Iseigaoka, Yahatanishi-ku, Kitakyushu 807-8555, Japan
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44
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Ho J, Benchimol S. Transcriptional repression mediated by the p53 tumour suppressor. Cell Death Differ 2003; 10:404-8. [PMID: 12719716 DOI: 10.1038/sj.cdd.4401191] [Citation(s) in RCA: 162] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- J Ho
- Department of Medical Biophysics, Ontario Cancer Institute, Princess Margaret Hospital, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9
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45
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Mauser A, Saito S, Appella E, Anderson CW, Seaman WT, Kenney S. The Epstein-Barr virus immediate-early protein BZLF1 regulates p53 function through multiple mechanisms. J Virol 2002; 76:12503-12. [PMID: 12438576 PMCID: PMC136659 DOI: 10.1128/jvi.76.24.12503-12512.2002] [Citation(s) in RCA: 85] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The Epstein-Barr virus (EBV) immediate-early protein BZLF1 is a transcriptional activator that mediates the switch between the latent and the lytic forms of EBV infection. It was previously reported that BZLF1 inhibits p53 transcriptional function in reporter gene assays. Here we further examined the effects of BZLF1 on p53 function by using a BZLF1-expressing adenovirus vector (AdBZLF1). Infection of cells with the AdBZLF1 vector increased the level of cellular p53 but prevented the induction of p53-dependent cellular target genes, such as p21 and MDM2. BZLF1-expressing cells had increased p53-specific DNA binding activity in electrophoretic mobility shift assays, increased p53 phosphorylation at multiple residues (including serines 6, 9, 15, 33, 46, 315, and 392), and increased acetylation at lysine 320 and lysine 382. Thus, the inhibitory effects of BZLF1 on p53 transcriptional function cannot be explained by its effects on p53 phosphorylation, acetylation, or DNA binding activity. BZLF1 substantially reduced the level of cellular TATA binding protein (TBP) in both normal human fibroblasts and A549 cells, and the inhibitory effects of BZLF1 on p53 transcriptional function could be partially rescued by the overexpression of TBP. Thus, BZLF1 has numerous effects on p53 posttranslational modification but may inhibit p53 transcriptional function in part through an indirect mechanism involving the suppression of TBP expression.
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Affiliation(s)
- Amy Mauser
- Department of Medicine, Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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46
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Jabbur JR, Tabor AD, Cheng X, Wang H, Uesugi M, Lozano G, Zhang W. Mdm-2 binding and TAF(II)31 recruitment is regulated by hydrogen bond disruption between the p53 residues Thr18 and Asp21. Oncogene 2002; 21:7100-13. [PMID: 12370832 DOI: 10.1038/sj.onc.1205856] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2002] [Revised: 06/26/2002] [Accepted: 07/05/2002] [Indexed: 11/08/2022]
Abstract
Analyses of five wild-type p53 containing cell lines revealed lineage specific differences in phosphorylation of Thr18 after treatment with ionizing (IR) or ultraviolet (UV) radiation. Importantly, Thr18 phosphorylation correlated with induction of the p53 downstream targets p21(Waf1/Cip1) (p21) and Mdm-2, suggesting a transactivation enhancing role. Thr18 phosphorylation has been shown to abolish side-chain hydrogen bonding between Thr18 and Asp21, an interaction necessary for stabilizing alpha-helical conformation within the transactivation domain. Mutagenesis-derived hydrogen bond disruption attenuated the interaction of p53 with the transactivation repressor Mdm-2 but had no direct effect on the interaction of p53 with the basal transcription factor TAF(II)31. However, prior incubation of p53 mutants with Mdm-2 modulated TAF(II)31 interaction with p53, suggesting Mdm-2 blocks the accessibility of p53 to TAF(II)31. Consistently, p53-null cells transfected with hydrogen bond disrupting p53 mutants demonstrated enhanced endogenous p21 expression, whereas p53/Mdm-2-double null cells exhibited no discernible differences in p21 expression. We conclude disruption of intramolecular hydrogen bonding between Thr18 and Asp21 enhances p53 transactivation by modulating Mdm-2 binding, facilitating TAF(II)31 recruitment.
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Affiliation(s)
- James R Jabbur
- Department of Pathology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, TX 77030, USA
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47
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Stein T, Crighton D, Warnock LJ, Milner J, White RJ. Several regions of p53 are involved in repression of RNA polymerase III transcription. Oncogene 2002; 21:5540-7. [PMID: 12165852 DOI: 10.1038/sj.onc.1205739] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2001] [Revised: 05/16/2002] [Accepted: 06/07/2002] [Indexed: 01/21/2023]
Abstract
The tumour suppressor p53 has been shown to regulate RNA polymerase (pol) III transcription both in vitro and in vivo. We have characterized the regions of p53 that contribute to this effect. Repression of pol III transcription in vivo does not require residues 13-19 near the N-terminus of p53 that are highly conserved through evolution. However, amino acids 22 and 23 in the adjacent transactivation domain do contribute to the inhibition of pol III activity. Deletions within the central DNA-binding core domain (residues 102-292) of p53 can entirely abolish the repression function in these assays, despite the fact that pol III templates contain no recognized p53 binding site. Deletion or substitution within the C-terminal domain of p53 can also compromise its ability to repress pol III activity in vitro and in transfected cells. These observations reveal that repression of pol III transcription is a complex function involving multiple regions of p53 extending throughout much of the protein.
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Affiliation(s)
- Torsten Stein
- Institute of Biomedical and Life Sciences, Division of Biochemistry and Molecular Biology, Davidson Building, University of Glasgow, Glasgow G12 8QQ, UK
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48
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Ard PG, Chatterjee C, Kunjibettu S, Adside LR, Gralinski LE, McMahon SB. Transcriptional regulation of the mdm2 oncogene by p53 requires TRRAP acetyltransferase complexes. Mol Cell Biol 2002; 22:5650-61. [PMID: 12138177 PMCID: PMC133988 DOI: 10.1128/mcb.22.16.5650-5661.2002] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The p53 tumor suppressor regulates the cellular response to genetic damage through its function as a sequence-specific transcription factor. Among the most well-characterized transcriptional targets of p53 is the mdm2 oncogene. Activation of mdm2 is critical in the p53 pathway because the mdm2 protein marks p53 for proteosome-mediated degradation, thereby providing a negative-feedback loop. Here we show that the ATM-related TRRAP protein functionally cooperates with p53 to activate mdm2 transcription. TRRAP is a component of several multiprotein acetyltransferase complexes implicated in both transcriptional regulation and DNA repair. In support of a role for these complexes in mdm2 expression, we show that transactivation of the mdm2 gene is augmented by pharmacological inhibition of cellular deacetylases. In vitro analysis demonstrates that p53 directly binds to a TRRAP domain previously shown to be an activator docking site. Furthermore, transfection of cells with antisense TRRAP blocks p53-dependent transcription of mdm2. Finally, using chromatin immunoprecipitation, we demonstrate direct p53-dependent recruitment of TRRAP to the mdm2 promoter, followed by increased histone acetylation. These findings suggest a model in which p53 directly recruits a TRRAP/acetyltransferase complex to the mdm2 gene to activate transcription. In addition, this study defines a novel biochemical mechanism utilized by the p53 tumor suppressor to regulate gene expression.
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Affiliation(s)
- Penny G Ard
- The Wistar Institute, Philadelphia, Pennsylvania 19104, USA
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49
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Jaiswal AS, Narayan S. SN2 DNA-alkylating agent-induced phosphorylation of p53 and activation of p21 gene expression. Mutat Res 2002; 500:17-30. [PMID: 11890931 DOI: 10.1016/s0027-5107(01)00296-2] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
p53 is an important player in the cellular response to genotoxic stress whose functions are regulated by phosphorylation of a number of serine and threonine residues. Phosphorylation of p53 influences its DNA-binding and gene regulation activities. This study examines p53 phosphorylation in HCT-116 (MMR-deficient) and HCT-116+ch3 (MMR-proficient) human colon cancer cells treated with a S(N)2 DNA-alkylating agent, methylmethane sulfonate (MMS). MMS induces phosphorylation of p53 on Ser15 and Ser392 in a dose- and time-dependent manner. MMS-induced p53 phosphorylation is independent of DNA mismatch repair (MMR) activity. Nuclear extracts from MMS-treated HCT-116 cells had higher p21WAF1/Cip1 (p21) promoter DNA-binding activity in vitro opposed to untreated cells. After MMS treatment, the activation of the cloned p21 promoter in a transient transfection assay and endogenous p21 mRNA levels in HCT-116(p53+/+) versus HCT-116(p53-/-) cells increased, which correlates with an increased levels of phospho-p53(Ser15) and phospho-p53(Ser392). These results suggest that SN2 DNA-alkylating agent-induced phosphorylation of p53 on Ser15 and Ser392 increases its DNA-binding properties to cause an increased expression of p21 that may play a role in cell cycle arrest and/or apoptosis of HCT-116 cells.
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Affiliation(s)
- Aruna S Jaiswal
- Department of Anatomy and Cell Biology, UF Shands Cancer Center, College of Medicine, University of Florida, P.O. Box 100232, Gainesville, FL 32610, USA
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50
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Vasseur S, Hoffmeister A, Garcia-Montero A, Mallo GV, Feil R, Kühbandner S, Dagorn JC, Iovanna JL. p8-deficient fibroblasts grow more rapidly and are more resistant to adriamycin-induced apoptosis. Oncogene 2002; 21:1685-94. [PMID: 11896600 DOI: 10.1038/sj.onc.1205222] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2001] [Revised: 11/26/2001] [Accepted: 12/03/2001] [Indexed: 12/26/2022]
Abstract
p8 is a stress-induced DNA-binding protein, biochemically related to the architectural chromatin binding HMG protein family and whose function is presently unknown. We obtained fibroblast from mice lacking p8 and found that p8 is involved in cell growth regulation and in apoptosis. p8(-/-) mouse embryonic fibroblasts (MEFs) grow more rapidly than p8(+/+) MEFs. This might be explained by the higher intracellular level and activity of the Cdk2 and Cdk4 observed in p8(-/-) MEFs, which in turn may result, at least in part, from the concomitant decrease observed in the amount of cyclin-dependent kinase inhibitor p27. We also report that p8 mRNA expression is strongly activated in fibroblasts after cell growth arrest induced by serum deprivation or confluence. As expected, MEFs expressing p8 arrest their growth more rapidly after serum deprivation than MEFs lacking p8, which strongly suggests that p8 over-expression is implicated in cell growth arrest. On the other hand, p8(+/+) MEFs are more sensitive than p8(-/-) MEFs to the apoptosis induced by adriamycin treatment. p53 might be involved, as p8 expression increases its intracellular amount and trans-activation capacity. Finally, demonstration that p53 is a negative trans-activator of p8 suggests the presence of a complex autoregulatory loop. In conclusion, p8 is a cell growth inhibitor that facilitates apoptosis induced in fibroblasts by DNA damage.
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Affiliation(s)
- Sophie Vasseur
- Centre de Recherche INSERM, EMI 0116, Parc Scientifique et Technologique de Luminy, 163 Av. de Luminy, F-13009 Marseille, France
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