1
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Corrigan AN, Lemkul JA. Electronic Polarization at the Interface between the p53 Transactivation Domain and Two Binding Partners. J Phys Chem B 2022; 126:4814-4827. [PMID: 35749260 PMCID: PMC9267131 DOI: 10.1021/acs.jpcb.2c02268] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Intrinsically disordered proteins (IDPs) are an abundant class of highly charged proteins that participate in numerous crucial biological processes, often in regulatory roles. IDPs do not have one major free energy minimum with a dominant structure, instead existing as conformational ensembles of multiple semistable conformations. p53 is a prototypical protein with disordered regions and binds to many structurally diverse partners, making it a useful model for exploring the role of electrostatic interactions at IDP binding interfaces. In this study, we used the Drude-2019 force field to simulate the p53 transactivation domain with two protein partners to probe the role of electrostatic interactions in IDP protein-protein interactions. We found that the Drude-2019 polarizable force field reasonably reproduced experimental chemical shifts of the p53 transactivation domain (TAD) in one complex for which these data are available. We also found that the proteins in these complexes displayed dipole response at specific residues of each protein and that residues primarily involved in binding showed a large percent change in dipole moment between the unbound and complexed states. Probing the role of electrostatic interactions in IDP binding can allow us greater fundamental understanding of these interactions and may help with targeting p53 or its partners for drug design.
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Affiliation(s)
| | - Justin A. Lemkul
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 20461, United States,Center for Drug Discovery, Virginia Tech, Blacksburg, VA 20461, United States,Corresponding Author: , Address: 111 Engel Hall, 340 West Campus Dr., Blacksburg, VA 24061, Phone: +1 (540) 231-3129
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2
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Rational design of a helical peptide inhibitor targeting c-Myb–KIX interaction. Sci Rep 2022; 12:816. [PMID: 35058484 PMCID: PMC8776815 DOI: 10.1038/s41598-021-04497-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 12/22/2021] [Indexed: 01/05/2023] Open
Abstract
The transcription factor c-Myb promotes the proliferation of hematopoietic cells by interacting with the KIX domain of CREB-binding protein; however, its aberrant expression causes leukemia. Therefore, inhibitors of the c-Myb–KIX interaction are potentially useful as antitumor drugs. Since the intrinsically disordered transactivation domain (TAD) of c-Myb binds KIX via a conformational selection mechanism where helix formation precedes binding, stabilizing the helical structure of c-Myb TAD is expected to increase the KIX-binding affinity. Here, to develop an inhibitor of the c-Myb–KIX interaction, we designed mutants of the c-Myb TAD peptide fragment where the helical structure is stabilized, based on theoretical predictions using AGADIR. Three of the four initially designed peptides each had a different Lys-to-Arg substitution on the helix surface opposite the KIX-binding interface. Furthermore, the triple mutant with three Lys-to-Arg substitutions, named RRR, showed a high helical propensity and achieved three-fold higher affinity to KIX than the wild-type TAD with a dissociation constant of 80 nM. Moreover, the RRR inhibitor efficiently competed out the c-Myb–KIX interaction. These results suggest that stabilizing the helical structure based on theoretical predictions, especially by conservative Lys-to-Arg substitutions, is a simple and useful strategy for designing helical peptide inhibitors of protein–protein interactions.
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3
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Semesta KM, Tian R, Kampmann M, von Zastrow M, Tsvetanova NG. A high-throughput CRISPR interference screen for dissecting functional regulators of GPCR/cAMP signaling. PLoS Genet 2020; 16:e1009103. [PMID: 33052901 PMCID: PMC7588078 DOI: 10.1371/journal.pgen.1009103] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 10/26/2020] [Accepted: 09/08/2020] [Indexed: 12/27/2022] Open
Abstract
G protein-coupled receptors (GPCRs) allow cells to respond to chemical and sensory stimuli through generation of second messengers, such as cyclic AMP (cAMP), which in turn mediate a myriad of processes, including cell survival, proliferation, and differentiation. In order to gain deeper insights into the complex biology and physiology of these key cellular pathways, it is critical to be able to globally map the molecular factors that shape cascade function. Yet, to this date, efforts to systematically identify regulators of GPCR/cAMP signaling have been lacking. Here, we combined genome-wide screening based on CRISPR interference with a novel sortable transcriptional reporter that provides robust readout for cAMP signaling, and carried out a functional screen for regulators of the pathway. Due to the sortable nature of the platform, we were able to assay regulators with strong and moderate phenotypes by analyzing sgRNA distribution among three fractions with distinct reporter expression. We identified 45 regulators with strong and 50 regulators with moderate phenotypes not previously known to be involved in cAMP signaling. In follow-up experiments, we validated the functional effects of seven newly discovered mediators (NUP93, PRIM1, RUVBL1, PKMYT1, TP53, SF3A2, and HRAS), and showed that they control distinct steps of the pathway. Thus, our study provides proof of principle that the screening platform can be applied successfully to identify bona fide regulators of GPCR/second messenger cascades in an unbiased and high-throughput manner, and illuminates the remarkable functional diversity among GPCR regulators.
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Affiliation(s)
- Khairunnisa Mentari Semesta
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Ruilin Tian
- Institute for Neurodegenerative Diseases, Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Chen-Zuckerberg Biohub, San Francisco, California, United States of America
- Biophysics Graduate Program, University of California, San Francisco, California, United States of America
| | - Martin Kampmann
- Institute for Neurodegenerative Diseases, Department of Biochemistry and Biophysics, University of California, San Francisco, California, United States of America
- Chen-Zuckerberg Biohub, San Francisco, California, United States of America
| | - Mark von Zastrow
- Department of Psychiatry, University of California, San Francisco, California, United States of America
- Department of Cellular & Molecular Pharmacology, University of California, San Francisco, California, United States of America
| | - Nikoleta G. Tsvetanova
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
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4
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Gajendran B, Durai P, Madhu Varier K, Chinnasamy A. A novel phytosterol isolated from Datura inoxia, RinoxiaB is a potential cure colon cancer agent by targeting BAX/Bcl2 pathway. Bioorg Med Chem 2019; 28:115242. [PMID: 31866271 DOI: 10.1016/j.bmc.2019.115242] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 11/25/2019] [Accepted: 11/25/2019] [Indexed: 12/12/2022]
Abstract
Plant sterols have been widely used as chemotherapeutic agents for colorectal cancer for years together. In this study, a novel phytosterol was isolated and characterized from the leaf extract of a medicinal plant, Datura inoxia and was coined as RinoxiaB (RB). This phytosterol was observed to have antiproliferative activity against human colon adenocarcinoma cells, HCT 15. The cell viability assay revealed the IC50 value of the RB as 4 µM. Moreover, RB treated cells showed prominent morphological changes dose dependently and progressively increased the number of dead cells. Additionally, results of the comet, flow cytometry, and cell cycle analysis revealed that the majority of cells were arrested in their S and G2/M phase by blocking the mitotic spindle formation. The western blot analysis (Bcl-2, BAX, Cytochrome C, Caspases 9 & 3) clearly indicated that RB has the ability to induce apoptosis by significantly upregulating (P < 0.05) Bcl-2 and causing mitochondrial damage leading to Cytochrome C release and activation of caspases, which subsequently results in downregulation of BAX expression in the cytosol. Furthermore, the expression of tumor suppressors (p53 and p21) and cell cycle regulatory proteins (Cyclins D1 & B1) suggested that RB inhibit cell proliferation. Thus, the present finding concludes that RB can offer possible apoptotic effects by targeting BAX/Bcl2 pathway in HCT 15 cells, thus alleviating colon cancer.
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Affiliation(s)
- Babu Gajendran
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu, India; State Key Laboratory of Functions and Applications of Medicinal Plants, Guizhou Medical University, Guiyang 550014, Guizhou Province, People's Republic of China; Key Laboratory of Chemistry for Natural Products of Guizhou Province and Chinese Academy of Sciences, Guiyang 550014, Guizhou Province, People's Republic of China
| | - Prabhu Durai
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu, India
| | - Krishnapriya Madhu Varier
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu, India; Department of Medical Biochemistry, Dr. ALM PGIBMS, University of Madras, Taramani Campus, Chennai 600113, Tamil Nadu, India
| | - Arulvasu Chinnasamy
- Department of Zoology, University of Madras, Guindy Campus, Chennai 600025, Tamil Nadu, India.
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5
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Zhu S, Khatun R, Lento C, Sheng Y, Wilson DJ. Enhanced Binding Affinity via Destabilization of the Unbound State: A Millisecond Hydrogen–Deuterium Exchange Study of the Interaction between p53 and a Pleckstrin Homology Domain. Biochemistry 2017; 56:4127-4133. [DOI: 10.1021/acs.biochem.7b00193] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Shaolong Zhu
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
| | - Rahima Khatun
- Department
of Biology, York University, Toronto, Ontario, Canada M3J 1P3
| | - Cristina Lento
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
| | - Yi Sheng
- Department
of Biology, York University, Toronto, Ontario, Canada M3J 1P3
| | - Derek J. Wilson
- Department
of Chemistry, York University, Toronto, Ontario, Canada M3J 1P3
- Centre
for Research in Mass Spectrometry, York University, Toronto, Ontario, Canada M3J 1P3
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6
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Wright DG, Marchal C, Hoang K, Ankney JA, Nguyen ST, Rushing AW, Polakowski N, Miotto B, Lemasson I. Human T-cell leukemia virus type-1-encoded protein HBZ represses p53 function by inhibiting the acetyltransferase activity of p300/CBP and HBO1. Oncotarget 2016; 7:1687-706. [PMID: 26625199 PMCID: PMC4811490 DOI: 10.18632/oncotarget.6424] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/15/2015] [Indexed: 01/31/2023] Open
Abstract
Adult T-cell leukemia (ATL) is an often fatal malignancy caused by infection with the complex retrovirus, human T-cell Leukemia Virus, type 1 (HTLV-1). In ATL patient samples, the tumor suppressor, p53, is infrequently mutated; however, it has been shown to be inactivated by the viral protein, Tax. Here, we show that another HTLV-1 protein, HBZ, represses p53 activity. In HCT116 p53+/+ cells treated with the DNA-damaging agent, etoposide, HBZ reduced p53-mediated activation of p21/CDKN1A and GADD45A expression, which was associated with a delay in G2 phase-arrest. These effects were attributed to direct inhibition of the histone acetyltransferase (HAT) activity of p300/CBP by HBZ, causing a reduction in p53 acetylation, which has be linked to decreased p53 activity. In addition, HBZ bound to, and inhibited the HAT activity of HBO1. Although HBO1 did not acetylate p53, it acted as a coactivator for p53 at the p21/CDKN1A promoter. Therefore, through interactions with two separate HAT proteins, HBZ impairs the ability of p53 to activate transcription. This mechanism may explain how p53 activity is restricted in ATL cells that do not express Tax due to modifications of the HTLV-1 provirus, which accounts for a majority of patient samples.
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Affiliation(s)
- Diana G Wright
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - Claire Marchal
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216, CNRS, Paris, France
| | - Kimson Hoang
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - John A Ankney
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA.,Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Stephanie T Nguyen
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - Amanda W Rushing
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - Nicholas Polakowski
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
| | - Benoit Miotto
- Université Paris Diderot, Sorbonne Paris Cité, Epigenetics and Cell Fate, UMR 7216, CNRS, Paris, France.,INSERM, U1016, Institut Cochin, Paris, France.,CNRS, UMR8104, Paris, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Isabelle Lemasson
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, NC, USA
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7
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Karimi M, Mohammadi H, Hemmatzadeh M, Mohammadi A, Rafatpanah H, Baradaran B. Role of the HTLV-1 viral factors in the induction of apoptosis. Biomed Pharmacother 2016; 85:334-347. [PMID: 27887847 DOI: 10.1016/j.biopha.2016.11.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 11/07/2016] [Accepted: 11/08/2016] [Indexed: 12/22/2022] Open
Abstract
Adult T-cell leukemia (ATL) and HTLV-1-associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) are the two main diseases that are caused by the HTLV-1 virus. One of the features of HTLV-1 infection is its resistance against programmed cell death, which maintains the survival of cells to oncogenic transformation and underlies the viruses' therapeutic resistance. Two main genes by which the virus develops cancer are Tax and HBZ; playing an essential role in angiogenesis in regulating viral transcription and modulating multiple host factors as well as apoptosis pathways. Here we have reviewed by prior research how the apoptosis pathways are suppressed by the Tax and HBZ and new drugs which have been designed to deal with this suppression.
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Affiliation(s)
- Mohammad Karimi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Immunology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran; Tabriz University of Medical Sciences, International Branch (Aras), Tabriz, Iran
| | - Hamed Mohammadi
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Immunology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Maryam Hemmatzadeh
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; Department of Immunology, School of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Asadollah Mohammadi
- Inflammation and Inflammatory Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Houshang Rafatpanah
- Inflammation and Inflammatory Diseases Research Center, Mashhad University of Medical Sciences, Mashhad, Iran.
| | - Behzad Baradaran
- Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran.
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8
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Haberz P, Arai M, Martinez-Yamout MA, Dyson HJ, Wright PE. Mapping the interactions of adenoviral E1A proteins with the p160 nuclear receptor coactivator binding domain of CBP. Protein Sci 2016; 25:2256-2267. [PMID: 27699893 DOI: 10.1002/pro.3059] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Revised: 09/28/2016] [Accepted: 09/30/2016] [Indexed: 01/03/2023]
Abstract
Many viruses deregulate the cell and force transcription of viral genes by competing with cellular proteins for binding to the transcriptional co-activators CREB-binding protein (CBP) and p300. Through its interactions with CBP/p300 and the retinoblastoma protein, the adenovirus (AdV) early region 1A (E1A) oncoprotein hijacks the cell cycle and, in rodents, transforms the cell; the mechanistic and structural basis for these effects remain unclear. In this study we compare the affinity of protein constructs from the E1A proteins from two adenovirus serotypes, non-oncogenic AdV5 and highly oncogenic AdV12, for binding to the nuclear receptor coactivator binding domain (NCBD) of CBP. NMR spectra show that the E1A constructs from both serotypes are intrinsically disordered in the free state and that each contains three homologous binding sites for the NCBD, one in the N-terminal region and two within conserved region 1 (CR1) of E1A. The binding sites in CR1 correspond to the motifs that bind the retinoblastoma protein and the TAZ2 domain of CBP/p300. The E1A and NCBD peptides fold synergistically upon complex formation. Binding affinities determined from NMR titrations show that, although the overall affinities for AdV5 and AdV12 E1A are comparable, there are significant differences between the two E1A serotypes in the relative strength with which their constituent interaction motifs bind to the NCBD. The individual E1A interaction motifs were unable to compete effectively with p53 for binding to the NCBD and both the N-terminal region and CR1 region of E1A are required for efficient competition with p53.
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Affiliation(s)
- Peter Haberz
- Department of Integrative Structural and Computational Biology and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, California
| | - Munehito Arai
- Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Meguro, Tokyo, 153-8902, Japan
| | - Maria A Martinez-Yamout
- Department of Integrative Structural and Computational Biology and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, California
| | - H Jane Dyson
- Department of Integrative Structural and Computational Biology and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, California
| | - Peter E Wright
- Department of Integrative Structural and Computational Biology and The Skaggs Institute of Chemical Biology, The Scripps Research Institute, La Jolla, California
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9
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Recognition of the disordered p53 transactivation domain by the transcriptional adapter zinc finger domains of CREB-binding protein. Proc Natl Acad Sci U S A 2016; 113:E1853-62. [PMID: 26976603 DOI: 10.1073/pnas.1602487113] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
An important component of the activity of p53 as a tumor suppressor is its interaction with the transcriptional coactivators cyclic-AMP response element-binding protein (CREB)-binding protein (CBP) and p300, which activate transcription of p53-regulated stress response genes and stabilize p53 against ubiquitin-mediated degradation. The highest affinity interactions are between the intrinsically disordered N-terminal transactivation domain (TAD) of p53 and the TAZ1 and TAZ2 domains of CBP/p300. The NMR spectra of simple binary complexes of the TAZ1 and TAZ2 domains with the p53TAD suffer from exchange broadening, but innovations in construct design and isotopic labeling have enabled us to obtain high-resolution structures using fusion proteins, uniformly labeled in the case of the TAZ2-p53TAD fusion and segmentally labeled through transintein splicing for the TAZ1-p53TAD fusion. The p53TAD is bipartite, with two interaction motifs, termed AD1 and AD2, which fold to form short amphipathic helices upon binding to TAZ1 and TAZ2 whereas intervening regions of the p53TAD remain flexible. Both the AD1 and AD2 motifs bind to hydrophobic surfaces of the TAZ domains, with AD2 making more extensive hydrophobic contacts consistent with its greater contribution to the binding affinity. Binding of AD1 and AD2 is synergistic, and structural studies performed with isolated motifs can be misleading. The present structures of the full-length p53TAD complexes demonstrate the versatility of the interactions available to an intrinsically disordered domain containing bipartite interaction motifs and provide valuable insights into the structural basis of the affinity changes that occur upon stress-related posttranslational modification.
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10
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Yoon JW, Lamm M, Iannaccone S, Higashiyama N, Leong KF, Iannaccone P, Walterhouse D. p53 modulates the activity of the GLI1 oncogene through interactions with the shared coactivator TAF9. DNA Repair (Amst) 2015; 34:9-17. [PMID: 26282181 DOI: 10.1016/j.dnarep.2015.06.006] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 06/11/2015] [Indexed: 01/20/2023]
Abstract
The GLI1 oncogene and p53 tumor suppressor gene function in an inhibitory loop that controls stem cell and tumor cell numbers. Since GLI1 and p53 both interact with the coactivator TATA Binding Protein Associated Factor 9 (TAF9), we hypothesized that competition between these transcription factors for TAF9 in cancer cells may contribute to the inhibitory loop and directly affect GLI1 function and cellular phenotype. We showed that TAF9 interacts with the oncogenic GLI family members GLI1 and GLI2 but not GLI3 in cell-free pull-down assays and with GLI1 in rhabdomyosarcoma and osteosarcoma cell lines. Removal of the TAF9-binding acidic alpha helical transactivation domain of GLI1 produced a significant reduction in the ability of GLI1 to transform cells. We then introduced a point mutation into GLI1 (L1052I) that eliminates TAF9 binding and a point mutation into GLI3 (I1510L) that establishes binding. Wild-type and mutant GLI proteins that bind TAF9 showed enhanced transactivating and cell transforming activity compared with those that did not. Therefore, GLI-TAF9 binding appears important for oncogenic activity. We then determined whether wild-type p53 down-regulates GLI function by sequestering TAF9. We showed that p53 binds TAF9 with greater affinity than does GLI1 and that co-expression of p53 with GLI1 or GLI2 down-regulated GLI-induced transactivation, which could be abrogated using mutant forms of GLI1 or p53. This suggests that p53 sequesters TAF9 from GLI1, which may contribute to inhibition of GLI1 activity by p53 and potentially impact therapeutic success of agents targeting GLI-TAF9 interactions in cancer.
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Affiliation(s)
- Joon Won Yoon
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - Marilyn Lamm
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - Stephen Iannaccone
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - Nicole Higashiyama
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - King Fu Leong
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - Philip Iannaccone
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA
| | - David Walterhouse
- Developmental Biology Program of the Stanley Manne Children's Research Institute, Northwestern University Feinberg School of Medicine Chicago, IL 60611, USA.
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11
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Thakur JK, Yadav A, Yadav G. Molecular recognition by the KIX domain and its role in gene regulation. Nucleic Acids Res 2013; 42:2112-25. [PMID: 24253305 PMCID: PMC3936767 DOI: 10.1093/nar/gkt1147] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
The kinase-inducible domain interacting (KIX) domain is a highly conserved independently folding three-helix bundle that serves as a docking site for transcription factors, whereupon promoter activation and target specificity are achieved during gene regulation. This docking event is a harbinger of an intricate multi-protein assembly at the transcriptional apparatus and is regulated in a highly precise manner in view of the critical role it plays in multiple cellular processes. KIX domains have been characterized in transcriptional coactivators such as p300/CREB-binding protein and mediator of RNA polymerase II transcription subunit 15, and even recQ protein-like 5 helicases in various organisms. Their targets are often intrinsically disordered regions within the transactivation domains of transcription factors that attain stable secondary structure only upon complexation with KIX. In this article, we review the KIX domain in terms of its sequence and structure and present the various implications of its ability to act as a transcriptional switch, the mechanistic basis of molecular recognition by KIX, its binding specificity, target promiscuity, combinatorial potential and unique mode of regulation via allostery. We also discuss the possible roles of KIX domains in plants and hope that this review will accelerate scientific interest in KIX and pave the way for novel avenues of research on this critical domain.
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Affiliation(s)
- Jitendra K Thakur
- National Institute of Plant Genome Research (NIPGR), Aruna Asaf Ali Marg, New Delhi 110067, India
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12
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Sequence and expression analyses of KIX domain proteins suggest their importance in seed development and determination of seed size in rice, and genome stability in Arabidopsis. Mol Genet Genomics 2013; 288:329-46. [PMID: 23756993 DOI: 10.1007/s00438-013-0753-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Accepted: 05/17/2013] [Indexed: 12/26/2022]
Abstract
The KIX domain, which mediates protein-protein interactions, was first discovered as a motif in the large multidomain transcriptional activator histone acetyltransferase p300/CBP. Later, the domain was also found in Mediator subunit MED15, where it interacts with many transcription factors. In both proteins, the KIX domain is a target of activation domains of diverse transcription activators. It was found to be an essential component of several specific gene-activation pathways in fungi and metazoans. Not much is known about KIX domain proteins in plants. This study aims to characterize all the KIX domain proteins encoded by the genomes of Arabidopsis and rice. All identified KIX domain proteins are presented, together with their chromosomal locations, phylogenetic analysis, expression and SNP analyses. KIX domains were found not only in p300/CBP- and MED15-like plant proteins, but also in F-box proteins in rice and DNA helicase in Arabidopsis, suggesting roles of KIX domains in ubiquitin-mediated proteasomal degradation and genome stability. Expression analysis revealed overlapping expression of OsKIX_3, OsKIX_5 and OsKIX_7 in different stages of rice seeds development. Moreover, an association analysis of 136 in silico mined SNP loci in 23 different rice genotypes with grain-length information identified three non-synonymous SNP loci in these three rice genes showing strong association with long- and short-grain differentiation. Interestingly, these SNPs were located within KIX domain encoding sequences. Overall, this study lays a foundation for functional analysis of KIX domain proteins in plants.
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13
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Jenkins LMM, Durell SR, Mazur SJ, Appella E. p53 N-terminal phosphorylation: a defining layer of complex regulation. Carcinogenesis 2012; 33:1441-9. [PMID: 22505655 DOI: 10.1093/carcin/bgs145] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The p53 tumor suppressor is a critical component of the cellular response to stress. As it can inhibit cell growth, p53 is mutated or functionally inactivated in most tumors. A multitude of protein-protein interactions with transcriptional cofactors are central to p53-dependent responses. In its activated state, p53 is extensively modified in both the N- and C-terminal regions of the protein. These modifications, especially phosphorylation of serine and threonine residues in the N-terminal transactivation domain, affect p53 stability and activity by modulating the affinity of protein-protein interactions. Here, we review recent findings from in vitro and in vivo studies on the role of p53 N-terminal phosphorylation. These modifications can either positively or negatively affect p53 and add a second layer of complex regulation to the divergent interactions of the p53 transactivation domain.
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Affiliation(s)
- Lisa M Miller Jenkins
- Laboratory of Cell Biology, National Cancer Institute, NIH, 37 Convent Drive, Room 2140, Bethesda, MD 20892, USA
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14
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Cook PR, Polakowski N, Lemasson I. HTLV-1 HBZ protein deregulates interactions between cellular factors and the KIX domain of p300/CBP. J Mol Biol 2011; 409:384-98. [PMID: 21497608 DOI: 10.1016/j.jmb.2011.04.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2011] [Revised: 04/01/2011] [Accepted: 04/01/2011] [Indexed: 12/11/2022]
Abstract
The complex retrovirus human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia. Deregulation of cellular transcription is thought to be an important step for T-cell transformation caused by viral infection. HTLV-1 basic leucine zipper factor (HBZ) is one of the viral proteins believed to be involved in this process, as it deregulates the expression of numerous cellular genes. In the context of the provirus, HBZ represses HTLV-1 transcription, in part, by binding to the homologous cellular coactivators p300 and CBP. These coactivators play a central role in transcriptional regulation. In this study, we determined that HBZ binds with high affinity to the KIX domain of p300/CBP. This domain contains two binding surfaces that are differentially targeted by multiple cellular factors. We show that two φXXφφ motifs in the activation domain of HBZ mediate binding to a single surface of the KIX domain, the mixed-lineage leukemia (MLL) binding surface. Formation of this interaction inhibits binding of MLL to the KIX domain while enhancing the binding of the transcription factor c-Myb to the opposite surface of KIX. Consequently, HBZ inhibits transcriptional activation mediated by MLL and enhances activation mediated by c-Myb. CREB, which binds the same surface of KIX as c-Myb, also exhibited an increase in activity through HBZ. These results indicate that HBZ is able to alter gene expression by competing with transcription factors for the occupancy of one surface of KIX while enhancing the binding of factors to the other surface.
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Affiliation(s)
- Pamela R Cook
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 278374, USA
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15
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Ozaki T, Kubo N, Nakagawara A. p73-Binding Partners and Their Functional Significance. INTERNATIONAL JOURNAL OF PROTEOMICS 2011; 2010:283863. [PMID: 22084676 PMCID: PMC3195385 DOI: 10.1155/2010/283863] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Accepted: 10/26/2010] [Indexed: 12/21/2022]
Abstract
p73 is one of the tumor-suppressor p53 family of nuclear transcription factor. As expected from the structural similarity between p53 and p73, p73 has a tumor-suppressive function. However, p73 was rarely mutated in human primary tumors. Under normal physiological conditions, p73 is kept at an extremely low level to allow cells normal growth. In response to a certain subset of DNA damages, p73 is induced dramatically and transactivates an overlapping set of p53-target genes implicated in the promotion of cell cycle arrest and/or apoptotic cell death. Cells undergo cell cycle arrest and/or apoptotic cell death depending on the type and strength of DNA damages. p73 is regulated largely through the posttranslational modifications such as phosphorylation and acetylation. These chemical modifications are tightly linked to direct protein-protein interactions. In the present paper, the authors describe the functional significance of the protein-protein interactions in the regulation of proapoptotic p73.
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Affiliation(s)
- Toshinori Ozaki
- Laboratory of Anti-tumor Research, Chiba Cancer Center Research Institute, Chiba 260-8717, Japan
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16
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Lee CW, Martinez-Yamout MA, Dyson HJ, Wright PE. Structure of the p53 transactivation domain in complex with the nuclear receptor coactivator binding domain of CREB binding protein. Biochemistry 2010; 49:9964-71. [PMID: 20961098 DOI: 10.1021/bi1012996] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The activity and stability of the tumor suppressor p53 are regulated by interactions with key cellular proteins such as MDM2 and CBP/p300. The transactivation domain (TAD) of p53 contains two subdomains (AD1 and AD2) and interacts directly with the N-terminal domain of MDM2 and with several domains of CBP/p300. Here we report the NMR structure of the full-length p53 TAD in complex with the nuclear coactivator binding domain (NCBD) of CBP. Both the p53 TAD and NCBD are intrinsically disordered and fold synergistically upon binding, as evidenced by the observed increase in helicity and increased level of dispersion of the amide proton resonances. The p53 TAD folds to form a pair of helices (denoted Pα1 and Pα2), which extend from Phe19 to Leu25 and from Pro47 to Trp53, respectively. In the complex, the NCBD forms a bundle of three helices (Cα1, residues 2066-2075; Cα2, residues 2081-2092; and Cα3, residues 2095-2105) with a hydrophobic groove into which p53 helices Pα1 and Pα2 dock. The polypeptide chain between the p53 helices remains flexible and makes no detectable intermolecular contacts with the NCBD. Complex formation is driven largely by hydrophobic contacts that form a stable intermolecular hydrophobic core. A salt bridge between D49 of p53 and R2105 of NCBD may contribute to the binding specificity. The structure provides the first insights into simultaneous binding of the AD1 and AD2 motifs to a target protein.
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Affiliation(s)
- Chul Won Lee
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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17
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Meyer KD, Lin SC, Bernecky C, Gao Y, Taatjes DJ. p53 activates transcription by directing structural shifts in Mediator. Nat Struct Mol Biol 2010; 17:753-60. [PMID: 20453859 PMCID: PMC2932482 DOI: 10.1038/nsmb.1816] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 03/23/2010] [Indexed: 12/24/2022]
Abstract
It is not well understood how the human Mediator complex, transcription factor IIH and RNA polymerase II (Pol II) work together with activators to initiate transcription. Activator binding alters Mediator structure, yet the functional consequences of such structural shifts remain unknown. The p53 C terminus and its activation domain interact with different Mediator subunits, and we find that each interaction differentially affects Mediator structure; strikingly, distinct p53-Mediator structures differentially affect Pol II activity. Only the p53 activation domain induces the formation of a large pocket domain at the Mediator-Pol II interaction site, and this correlates with activation of stalled Pol II to a productively elongating state. Moreover, we define a Mediator requirement for TFIIH-dependent Pol II C-terminal domain phosphorylation and identify substantial differences in Pol II C-terminal domain processing that correspond to distinct p53-Mediator structural states. Our results define a fundamental mechanism by which p53 activates transcription and suggest that Mediator structural shifts trigger activation of stalled Pol II complexes.
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Affiliation(s)
- Krista D Meyer
- Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
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18
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Lee CW, Arai M, Martinez-Yamout MA, Dyson HJ, Wright PE. Mapping the interactions of the p53 transactivation domain with the KIX domain of CBP. Biochemistry 2009; 48:2115-24. [PMID: 19220000 DOI: 10.1021/bi802055v] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Molecular interactions between the tumor suppressor p53 and the transcriptional coactivators CBP/p300 are critical for the regulation of p53 transactivation and stability. The transactivation domain (TAD) of p53 binds directly to several CBP/p300 domains (TAZ1, TAZ2, NCBD, and KIX). Here we map the interaction between the p53 TAD and the CBP KIX domain using isothermal titration calorimetry and NMR spectroscopy. KIX is a structural domain in CBP/p300 that can simultaneously bind two polypeptide ligands, such as the activation domain of MLL and the kinase-inducible activation domain (pKID) of CREB, using distinct interaction surfaces. The p53 TAD consists of two subdomains (AD1 and AD2); peptides corresponding to the isolated AD1 and AD2 subdomains interact with KIX with relatively low affinity, but a longer peptide containing both subdomains binds KIX tightly. In the context of the full-length p53 TAD, AD1 and AD2 bind synergistically to KIX. Mapping of the chemical shift perturbations onto the structure of KIX shows that isolated AD1 and AD2 peptides bind to both the MLL and pKID sites. Spin-labeling experiments show that the complex of the full-length p53 TAD with KIX is disordered, with the AD1 and AD2 subdomains each interacting with both the MLL and pKID binding surfaces. Phosphorylation of the p53 TAD at Thr18 or Ser20 increases the KIX binding affinity. The affinity is further enhanced by simultaneous phosphorylation of Thr18 and Ser20, and the specificity of the interaction is increased. The p53 TAD simultaneously occupies the two distinct sites that have been identified on the CBP KIX domain and efficiently competes for these sites with other known KIX-binding transcription factors.
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Affiliation(s)
- Chul Won Lee
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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19
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Posttranslational modification of p53: cooperative integrators of function. Cold Spring Harb Perspect Biol 2009; 1:a000950. [PMID: 20457558 DOI: 10.1101/cshperspect.a000950] [Citation(s) in RCA: 336] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The p53 protein is modified by as many as 50 individual posttranslational modifications. Many of these occur in response to genotoxic or nongenotoxic stresses and show interdependence, such that one or more modifications can nucleate subsequent events. This interdependent nature suggests a pathway that operates through multiple cooperative events as opposed to distinct functions for individual, isolated modifications. This concept, supported by recent investigations, which provide exquisite detail as to how various modifications mediate precise protein-protein interactions in a cooperative manner, may explain why knockin mice expressing p53 proteins substituted at one or just a few sites of modification typically show only subtle effects on p53 function. The present article focuses on recent, exciting progress and develops the idea that the impact of modification on p53 function is achieved through collective and integrated events.
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20
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Jenkins LMM, Yamaguchi H, Hayashi R, Cherry S, Tropea JE, Miller M, Wlodawer A, Appella E, Mazur SJ. Two distinct motifs within the p53 transactivation domain bind to the Taz2 domain of p300 and are differentially affected by phosphorylation. Biochemistry 2009; 48:1244-55. [PMID: 19166313 DOI: 10.1021/bi801716h] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The tumor suppressor p53 functions as a transcriptional activator for many genes, including several key genes involved in cell cycle arrest and apoptosis. Following DNA damage-induced stress, p53 undergoes extensive posttranslational modification, resulting in increased stability and activity. Two critical cofactors for p53-mediated transactivation are the histone acetyltransferase paralogues CREB-binding protein (CBP) and p300. The N-terminal transactivation domain of p53 interacts with several domains of CBP/p300, including the Taz2 domain. Here, we report the effects of specific p53 phosphorylations on its interaction with the Taz2 domain of p300. Using a competitive fluorescence anisotropy assay, we determined that monophosphorylation of p53 at Ser(15) or Thr(18) increased the affinity of p53(1-39) for Taz2, and diphosphorylations at Ser(15) and Ser(37) or Thr(18) and Ser(20) further increased the affinity. In addition, we identified a second binding site for Taz2 within p53 residues 35-59. This second site bound Taz2 with a similar affinity as the first site, but the binding was unaffected by phosphorylation. Thus, p53 posttranslational modification modulates only one of the two binding sites for p300 Taz2. Further investigation of Taz2 binding to p53(1-39) or p53(35-59) by isothermal titration calorimetry indicated that upon complex formation, the change in heat capacity at constant pressure, DeltaC(p), was negative for both sites, suggesting the importance of hydrophobic interactions. However, the more negative value of DeltaC(p) for Taz2 binding to the first (-330 cal/(mol.K)) compared to the second site (-234 cal/(mol.K)) suggests that the importance of nonpolar and polar interactions differs between the two sites.
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Affiliation(s)
- Lisa M Miller Jenkins
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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21
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Ferreon JC, Lee CW, Arai M, Martinez-Yamout MA, Dyson HJ, Wright PE. Cooperative regulation of p53 by modulation of ternary complex formation with CBP/p300 and HDM2. Proc Natl Acad Sci U S A 2009; 106:6591-6. [PMID: 19357310 PMCID: PMC2672497 DOI: 10.1073/pnas.0811023106] [Citation(s) in RCA: 169] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Indexed: 02/08/2023] Open
Abstract
The tumor suppressor activity of p53 is regulated by interactions with the ubiquitin ligase HDM2 and the general transcriptional coactivators CBP and p300. Using NMR spectroscopy and isothermal titration calorimetry, we have dissected the binding interactions between the N-terminal transactivation domain (TAD) of p53, the TAZ1, TAZ2, KIX, and nuclear receptor coactivator binding domains of CBP, and the p53-binding domain of HDM2. The p53 TAD contains amphipathic binding motifs within the AD1 and AD2 regions that mediate interactions with CBP and HDM2. Binding of the p53 TAD to CBP domains is dominated by interactions with AD2, although the affinity is enhanced by additional interactions with AD1. In contrast, binding of p53 TAD to HDM2 is mediated primarily by AD1. The p53 TAD can bind simultaneously to HDM2 (through AD1) and to any one of the CBP domains (through AD2) to form a ternary complex. Phosphorylation of p53 at T18 impairs binding to HDM2 and enhances affinity for the CBP KIX domain. Multisite phosphorylation of the p53 TAD at S15, T18, and S20 leads to increased affinity for the TAZ1 and KIX domains of CBP. These observations suggest a mechanism whereby HDM2 and CBP/p300 function synergistically to regulate the p53 response. In unstressed cells, CBP/p300, HDM2 and p53 form a ternary complex that promotes polyubiquitination and degradation of p53. After cellular stress and DNA damage, p53 becomes phosphorylated at T18 and other residues in the AD1 region, releases HDM2 and binds preferentially to CBP/p300, leading to stabilization and activation of p53.
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Affiliation(s)
- Josephine C. Ferreon
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
| | - Chul Won Lee
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
| | - Munehito Arai
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
- Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan
| | - Maria A. Martinez-Yamout
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
| | - H. Jane Dyson
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
| | - Peter E. Wright
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 N. Torrey Pines Road, La Jolla, CA 92037; and
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22
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Itahana Y, Ke H, Zhang Y. p53 Oligomerization is essential for its C-terminal lysine acetylation. J Biol Chem 2009; 284:5158-64. [PMID: 19106109 PMCID: PMC2643511 DOI: 10.1074/jbc.m805696200] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 12/03/2008] [Indexed: 11/06/2022] Open
Abstract
Acetylation of multiple lysine residues in the p53 plays critical roles in the protein stability and transcriptional activity of p53. To better understand how p53 acetylation is regulated, we generated a number of p53 mutants and examined acetylation of each mutant in transfected cells. We found that p53 mutants that are defective in tetramer formation are also defective in C-terminal lysine residue acetylation. Consistently, we found that several cancer-derived p53 mutants that bear mutations in the tetramerization domain cannot form oligomers and are defective in C-terminal lysine acetylation, and these mutants are inactive in p21 transactivation. We demonstrated that the acetyltransferase p300 interacts with and promotes acetylation of wild-type p53 but not with any of the artificially generated or human cancer-derived p53 mutants that are defective in oligomerization. These results, combined with a computer-aided crystal structure analysis, suggest a model in which p53 oligomerization precedes its acetylation by providing docking sites for acetyltransferases.
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Affiliation(s)
- Yoko Itahana
- Department of Radiation Oncology, University of North Carolina, Chapel Hill, North Carolina 27599-7512, USA
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23
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Banerjee P, Sieburg M, Samuelson E, Feuer G. Human T-cell lymphotropic virus type 1 infection of CD34+ hematopoietic progenitor cells induces cell cycle arrest by modulation of p21(cip1/waf1) and survivin. Stem Cells 2008; 26:3047-58. [PMID: 18818438 DOI: 10.1634/stemcells.2008-0353] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Human T-cell lymphotropic virus type 1 (HTLV-1) is an oncogenic retrovirus and the etiologic agent of adult T-cell leukemia (ATL), an aggressive CD4(+) malignancy. HTLV-2 is highly homologous to HTLV-1; however, infection with HTLV-2 has not been associated with lymphoproliferative diseases. Although HTLV-1 infection of CD4(+) lymphocytes induces cellular replication and transformation, infection of CD34(+) human hematopoietic progenitor cells (HPCs) strikingly results in G(0)/G(1) cell cycle arrest and suppression of in vitro clonogenic colony formation by induction of expression of the cdk inhibitor p21(cip1/waf1) (p21) and concurrent repression of survivin. Immature CD34(+)/CD38(-) hematopoietic stem cells (HSCs) were more susceptible to alterations of p21 and survivin expression as a result of HTLV-1 infection, in contrast to more mature CD34(+)/CD38(+) HPCs. Knockdown of p21 expression in HTLV-1-infected CD34(+) HPCs partially abrogated cell cycle arrest. Notably, HTLV-2, an HTLV strain that is not associated with leukemogenesis, does not significantly modulate p21 and survivin expression and does not suppress hematopoiesis from CD34(+) HPCs in vitro. We speculate that the remarkable differences in the activities displayed by CD34(+) HPCs following infection with HTLV-1 or HTLV-2 suggest that HTLV-1 uniquely exploits cell cycle arrest mechanisms to establish a latent infection in hematopoietic progenitor/hematopoietic stem cells and initiates preleukemic events in these cells, which eventually results in the manifestation of ATL.
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Affiliation(s)
- Prabal Banerjee
- Department of Microbiology and Immunology, State University of New York Upstate Medical University, Syracuse, New York 13210, USA
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24
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Human T-cell leukemia virus type 1 Tax modulates interferon-alpha signal transduction through competitive usage of the coactivator CBP/p300. Virology 2008; 379:306-13. [PMID: 18678383 DOI: 10.1016/j.virol.2008.06.035] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 06/18/2008] [Accepted: 06/30/2008] [Indexed: 11/22/2022]
Abstract
We describe here Tax protein of human T-cell leukemia virus type 1 (HTLV-1) as an interferon (IFN)-alpha antagonist counteracting the transactivation function of IFN-stimulated gene factor 3 (ISGF3). Co-expression of Tax, but not the Tax mutant unable to bind to CBP, significantly inhibited the reporter gene expression directed by IFN-stimulated regulatory elements, despite that the formation of DNA-binding ISGF3 complex was unaffected. Gene activation induced by STAT2 transcription domain was also inhibited by expression of Tax. Furthermore, Tax-mediated transcriptional inhibition was reversed by overexpression of p300. These observations indicate that Tax interferes with IFN-alpha-induced JAK-STAT pathway by competition with STAT2 for CBP/p300 binding. Consistently, GST pull-down assay showed that Tax dose-dependently inhibited binding of STAT2 to p300. This study suggests that Tax may prevent IFN-alpha from exerting its antiviral, antiproliferative and proapoptotic effects, thereby contributing to persistent viral infection and HTLV-1-associated oncogenesis.
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25
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Gavala ML, Pfeiffer ZA, Bertics PJ. The nucleotide receptor P2RX7 mediates ATP-induced CREB activation in human and murine monocytic cells. J Leukoc Biol 2008; 84:1159-71. [PMID: 18625910 DOI: 10.1189/jlb.0907612] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Nucleotide receptors serve as sensors of extracellular ATP and are important for immune function. The nucleotide receptor P2RX7 is a cell-surface, ligand-gated cation channel that has been implicated in many diseases, including arthritis, granuloma formation, sepsis, and tuberculosis. These disorders are often exacerbated by excessive mediator release from activated macrophages in the inflammatory microenvironment. Although P2RX7 activation can modulate monocyte/macrophage-induced inflammatory events, the relevant molecular mechanisms are poorly understood. Previous studies suggest that MAPK cascades and transcriptional control via CREB-linked pathways regulate the inflammatory capacity of monocytic cells. As P2RX7 promotes MAPK activation and inflammatory mediator production, we examined the involvement MAPK-induced CREB activation in P2RX7 action. Our data reveal that stimulation of multiple monocytic cell lines with P2RX7 agonists induces rapid CREB phosphorylation. In addition, we observed a lack of nucleotide-induced CREB phosphorylation in RAW 264.7 cells expressing nonfunctional P2RX7 and a gain of nucleotide-induced CREB phosphorylation in human embryonic kidney-293 cells that heterologously express human P2RX7. Furthermore, our results indicate that P2RX7 agonist-induced CREB phosphorylation is partly mediated via Ca(2+) fluxes and the MEK/ERK system. Mechanistic analyses revealed that macrophage stimulation with a P2RX7 agonist induces CREB/CREB-binding protein complex formation, which is necessary for CREB transcriptional activation. Also, we demonstrate that P2RX7 activation induces a known CREB-dependent gene (c-fos) and that dominant-negative CREB constructs attenuate this response. These studies support the idea that P2RX7 stimulation can directly regulate protein expression that is not dependent on costimulation with other immune modulators such as LPS.
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Affiliation(s)
- Monica L Gavala
- Department of Biomolecular Chemistry, University of Wisconsin, Madison, WI 53706, USA
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26
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Linnerth NM, Greenaway JB, Petrik JJ, Moorehead RA. cAMP response element-binding protein is expressed at high levels in human ovarian adenocarcinoma and regulates ovarian tumor cell proliferation. Int J Gynecol Cancer 2008; 18:1248-57. [PMID: 18554190 DOI: 10.1111/j.1525-1438.2007.01177.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Approximately 90% of human ovarian tumors result from transformation of ovarian surface epithelial cells. It has been hypothesized that repeated destruction of the epithelial cells during ovulation, followed by proliferation and migration of epithelial cells to restore the ovarian surface, renders these cells susceptible to mutagenic events. One of the proteins found to promote ovarian surface epithelial cell survival and proliferation was the transcription factor, cAMP response element-binding protein (CREB). Thus, the objective of this study was to determine whether CREB was also highly expressed in tumor cells originating from the ovarian epithelium. Using an ovarian cancer tissue array, it was observed that approximately 54% of the epithelial-derived human ovarian tumors displayed moderate or high levels of CREB immunostaining, while none of the normal ovarian samples did. Comparison of CREB levels in a human ovarian tumor cell line to those of a normal ovarian epithelial cell line revealed elevated levels of CREB and phosphorylated CREB in the ovarian tumor cells. To determine whether CREB regulated proliferation and/or apoptosis in the ovarian tumor cell line, CREB expression was suppressed using RNA interference. Decreased CREB expression significantly reduced ovarian tumor cell proliferation, while there was no effect on apoptosis in these cells. Finally, we showed that CREB is highly expressed in an in vivo murine model of ovarian tumorigenesis. Therefore, CREB is frequently overexpressed in ovarian cancer where it appears to promote cell proliferation.
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Affiliation(s)
- N M Linnerth
- Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, Canada
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27
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Activated p53 induces NF-kappaB DNA binding but suppresses its transcriptional activation. Biochem Biophys Res Commun 2008; 372:137-41. [PMID: 18477470 DOI: 10.1016/j.bbrc.2008.05.021] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2008] [Accepted: 05/01/2008] [Indexed: 11/21/2022]
Abstract
NF-kappaB plays an important role in oncogenesis. Recently, we have demonstrated that loss of p53 function enhances DNA binding and transcriptional activities of NF-kappaB via IKKalpha and IKKbeta, and that glycolysis, activated by NF-kappaB, has an integral role in oncogene-induced cell transformation. Here, we show that ectopically expressed p53 induces acetylation and phosphorylation at Ser 536 of p65, an NF-kappaB component, and enhances DNA-binding activity of NF-kappaB. However, activated p53 suppresses transcriptional activity of NF-kappaB. Under non-stimulating conditions, p65 formed a complex with IKKalpha and IKKbeta. Activated p53 bound to p65 on DNA and disrupted binding of p65 to IKKbeta. Moreover, histone H3 kinase activity, which requires transcriptional activation of NF-kappaB, was diminished by p53. Thus, activated p53 may suppress transcriptional activity of NF-kappaB through inhibition of IKK and histone H3 kinase on DNA, suggesting a novel p53-mediated suppression system for tumorigenesis.
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28
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Velu CS, Niture SK, Doneanu CE, Pattabiraman N, Srivenugopal KS. Human p53 is inhibited by glutathionylation of cysteines present in the proximal DNA-binding domain during oxidative stress. Biochemistry 2007; 46:7765-80. [PMID: 17555331 PMCID: PMC2518322 DOI: 10.1021/bi700425y] [Citation(s) in RCA: 159] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The cellular mechanisms that modulate the redox state of p53 tumor suppressor remain unclear, although its DNA binding function is known to be strongly inhibited by oxidative and nitrosative stresses. We show that human p53 is subjected to a new and reversible posttranslational modification, namely, S-glutathionylation in stressed states, including DNA damage. First, a rapid and direct incorporation of biotinylated GSH or GSSG into the purified recombinant p53 protein was observed. The modified p53 had a significantly weakened ability to bind its consensus DNA sequence. Reciprocal immunoprecipitations and a GST overlay assay showed that p53 in tumor cells was marginally glutathionylated; however, the level of modification increased greatly after oxidant and DNA-damaging treatments. GSH modification coexisted with the serine phophorylations in activated p53, and the thiol-conjugated protein was present in nuclei. When tumor cells treated with camptothecin or cisplatin were subsequently exposed to glutathione-enhancing agents, p53 underwent dethiolation accompanied by detectable increases in the level of p21waf1 expression, relative to the DNA-damaging drugs alone. Mass spectrometry of GSH-modified p53 protein identified cysteines 124, 141, and 182, all present in the proximal DNA-binding domain, as the sites of glutathionylation. Biotinylated maleimide also reacted rapidly with Cys141, implying that this is the most reactive cysteine on the p53 surface. The glutathionylatable cysteines were found to exist in a negatively charged microenvironment in cellular p53. Molecular modeling studies located Cys124 and -141 at the dimer interface of p53 and showed glutathionylation of either residue would inhibit p53-DNA association and also interfere with protein dimerization. These results show for the first time that shielding of reactive cysteines contributes to a negative regulation for human p53 and imply that such an inactivation of the transcription factor may represent an acute defensive response with significant consequences for oncogenesis.
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Affiliation(s)
- Chinavenmeni S. Velu
- Anticancer Resistance Research Group, Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106
| | - Suryakant K. Niture
- Anticancer Resistance Research Group, Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106
| | - Catalin E. Doneanu
- Mass Spectrometry Center, Department of Medicinal Chemistry, University of Washington, Seattle, WA 98195
| | - Nagarajan Pattabiraman
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC 20057
| | - Kalkunte S. Srivenugopal
- Anticancer Resistance Research Group, Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106
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29
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Ramírez JA, Nyborg JK. Molecular characterization of HTLV-1 Tax interaction with the KIX domain of CBP/p300. J Mol Biol 2007; 372:958-969. [PMID: 17707401 PMCID: PMC2039700 DOI: 10.1016/j.jmb.2007.06.062] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2007] [Revised: 06/20/2007] [Accepted: 06/20/2007] [Indexed: 01/12/2023]
Abstract
The viral oncoprotein Tax mediates transcriptional activation of human T-cell leukemia virus type 1 (HTLV-1). Both Tax and the cellular transcription factor CREB bind to viral cyclic AMP response elements (vCREs) located in the viral promoter. Tax and serine 133 phosphorylated CREB (pCREB) bound to the HTLV-1 promoter facilitate viral transcription via the recruitment of the large cellular coactivators CBP/p300. While the interaction between the phosphorylated kinase inducible domain (pKID) of pCREB and the KIX domain of CBP/p300 has been well characterized, the molecular interactions between KIX, full-length Tax, and pCREB have not been examined. Here we biochemically characterized the interaction between Tax and KIX in a physiologically relevant complex containing pCREB and vCRE DNA. Our data show that Tax and pCREB simultaneously and independently bind two distinct surfaces on the KIX domain: Tax binds KIX at the previously characterized mixed-lineage leukemia (MLL) protein interaction surface while pCREB binds KIX at the pKID-KIX interface. These results provide evidence for a model in which Tax and pCREB bind distinct surfaces of KIX for effective CBP/p300 recruitment to the HTLV-1 promoter. We also show that MLL competes with Tax for KIX binding, suggesting a novel mechanism of Tax oncogenesis in which normal MLL function is disrupted by Tax.
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Affiliation(s)
- Julita A Ramírez
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA
| | - Jennifer K Nyborg
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523-1870, USA.
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30
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Kim YM, Ramírez JA, Mick JE, Giebler HA, Yan JP, Nyborg JK. Molecular characterization of the Tax-containing HTLV-1 enhancer complex reveals a prominent role for CREB phosphorylation in Tax transactivation. J Biol Chem 2007; 282:18750-7. [PMID: 17449469 DOI: 10.1074/jbc.m700391200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Transcriptional activation of human T-cell leukemia virus type 1 (HTLV-1) is mediated by the viral oncoprotein Tax, which utilizes cellular transcriptional machinery to perform this function. The viral promoter carries three cyclic AMP-response elements (CREs), which are recognized by the cellular transcription factor cAMP-response element-binding protein (CREB). Tax binds to GC-rich sequences that immediately flank the CREs. The coactivator CREB-binding protein (CBP)/p300 binds to this promoter-bound ternary complex, which promotes the initiation of HTLV-1 transcription. Protein kinase A phosphorylation of CREB at serine 133 facilitates transcription from cellular CREs by recruiting CBP/p300 via its KIX domain. However, it remains controversial whether CREB phosphorylation plays a role in Tax transactivation. In this study, we biochemically characterized the quaternary complex formed by Tax, CREB, KIX, and the viral CRE by examining the individual molecular interactions that contribute to Tax stabilization in the complex. Our data show KIX, Ser(133)-phosphorylated CREB, and vCRE DNA are all required for stable Tax incorporation into the complex in vitro. Consonant with a fundamental role for CREB phosphorylation in Tax recruitment to the complex, we found that CREB is highly phosphorylated in a panel of HTLV-1-infected human T-cell lines. Significantly, we show that Tax is directly responsible for promoting elevated levels of CREB phosphorylation. Together, these data support a model in which Tax promotes CREB phosphorylation in vivo to ensure availability for Tax transactivation. Because pCREB has been implicated in leukemogenesis, enhancement of CREB phosphorylation by the virus may play a role in the etiology of adult T-cell leukemia.
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Affiliation(s)
- Young-Mi Kim
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA
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31
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Teufel DP, Freund SM, Bycroft M, Fersht AR. Four domains of p300 each bind tightly to a sequence spanning both transactivation subdomains of p53. Proc Natl Acad Sci U S A 2007; 104:7009-14. [PMID: 17438265 PMCID: PMC1855428 DOI: 10.1073/pnas.0702010104] [Citation(s) in RCA: 161] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transcriptional coactivator p300 binds to and mediates the transcriptional functions of the tetrameric tumor suppressor p53. Both proteins consist of independently folded domains linked by intrinsically disordered sequences. A well studied short sequence of the p53 transactivation domain, p53(15-29), binds weakly to four folded domains of p300 [Taz1/cysteine-histidine-rich region 1 (CH1), Kix, Taz2/CH3, IBiD], with dissociation constants (K(D)) in the 100 muM region. However, we found that a longer N-terminal transactivation domain construct p53(1-57) bound tightly to each p300 domain. Taz2/CH3 had the greatest affinity (K(D) = 27 nM) and competes with the N-terminal domain of Mdm2 for the p53 N terminus. p300 thus can protect the N terminus of p53 against the binding of other proteins. Mutations of p53 that abrogate transactivation (L22Q/W23S, W53Q/F54S) greatly weakened binding to each p300 domain, linking phenotypic defects to weakened coactivator binding. We propose a complex between tetrameric p53 and p300 in which four domains of p300 wrap around the four transactivation domains of p53.
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Affiliation(s)
- Daniel P. Teufel
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Stefan M. Freund
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Mark Bycroft
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
| | - Alan R. Fersht
- MRC Centre for Protein Engineering and Department of Chemistry, Cambridge University, MRC Centre, Hills Road,Cambridge CB2 2QH, United Kingdom
- *To whom correspondence should be addressed. E-mail:
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32
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Shanware NP, Trinh AT, Williams LM, Tibbetts RS. Coregulated ataxia telangiectasia-mutated and casein kinase sites modulate cAMP-response element-binding protein-coactivator interactions in response to DNA damage. J Biol Chem 2007; 282:6283-91. [PMID: 17209043 DOI: 10.1074/jbc.m610674200] [Citation(s) in RCA: 31] [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
The cyclic AMP-response element-binding protein (CREB) is a bZIP family transcription factor implicated as an oncoprotein and neuron survival factor. CREB is activated in response to cellular stimuli, including cAMP and Ca(2+), via phosphorylation of Ser-133, which promotes interaction between the kinase-inducible domain (KID) of CREB and the KID-interacting domain of CREB-binding protein (CBP). We previously demonstrated that the interaction between CREB and CBP is inhibited by DNA-damaging stimuli through a mechanism whereby CREB is phosphorylated by the ataxia telangiectasia-mutated (ATM) protein kinase. We now show that the ATM phosphorylation sites in CREB are functionally intertwined with a cluster of coregulated casein kinase (CK) sites. We demonstrate that DNA damage-induced phosphorylation of CREB occurs in three steps. The initial event in the CREB phosphorylation cascade is the phosphorylation of Ser-111, which is carried out by CK1 and CK2 under basal conditions and by ATM in response to ionizing radiation. The phosphorylation of Ser-111 triggers the CK2-dependent phosphorylation of Ser-108 and the CK1-dependent phosphorylation of Ser-114 and Ser-117. The phosphorylation of Ser-114 and Ser-117 by CK1 then renders CREB permissive for ATM-dependent phosphorylation on Ser-121. Mutation of Ser-121 alone abrogates ionizing radiation-dependent repression of CREB-CBP complexes, which can be recapitulated using a CK1 inhibitor. Our findings outline a complex mechanism of CREB phosphorylation in which coregulated ATM and CK sites control CREB transactivation potential by modulating its CBP-binding affinity. The coregulated ATM and CK sites identified in CREB may constitute a signaling motif that is common to other DNA damage-regulated substrates.
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Affiliation(s)
- Naval P Shanware
- Molecular and Cellular Pharmacology Program, Department of Pharmacology, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin 53706
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33
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Kaneshiro K, Tsutsumi S, Tsuji S, Shirahige K, Aburatani H. An integrated map of p53-binding sites and histone modification in the human ENCODE regions. Genomics 2006; 89:178-88. [PMID: 17085012 DOI: 10.1016/j.ygeno.2006.09.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2006] [Revised: 08/30/2006] [Accepted: 09/06/2006] [Indexed: 10/23/2022]
Abstract
TP53 (tumor protein p53; p53) regulates its target genes under various cellular stresses. By combining chromatin immunoprecipitation with oligonucleotide microarrays, we have mapped binding sites of p53 (p53-BS) in the genome of HCT116 human colon carcinoma cells, along with those of acetylated H3, acetylated H4, and methylated H3-K4. We analyzed a 30-Mb portion of the human genome selected as a representative model by the ENCODE Consortium. In the region, we found 37 p53-BS, of which the p53-binding motif was present in 32 (86%). Acetylated histone H3 and H4 were detected at 14 (38%) and 33 (89%) of the p53-BS, respectively. A significant portion (58%) of H4 acetylation in the p53-BS was not accompanied by H3 acetylation. Acetyl H3 were preferentially located at the 5' and 3' ends of genes, whereas acetyl H4 were distributed widely across the genome. These results provide novel insights into how p53 binding coordinates with histone modification in human.
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Affiliation(s)
- Kiyofumi Kaneshiro
- Genome Science Division, Research Center for Advanced Science and Technology (RCAST), University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo 153-8904, Japan
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34
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Harakeh S, Diab-Assaf M, Abu-El-Ardat K, Niedzwiecki A, Rath M. Mechanistic aspects of apoptosis induction by l-lysine in both HTLV-1-positive and -negative cell lines. Chem Biol Interact 2006; 164:102-14. [PMID: 17049505 DOI: 10.1016/j.cbi.2006.09.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 08/31/2006] [Accepted: 09/01/2006] [Indexed: 10/24/2022]
Abstract
The retrovirus human T-cell lymphotrophic virus type-1 (HTLV-1) causes adult T-cell leukemia (ATL), which remains with no cure. This study evaluates the effects of l-lysine on proliferation and induction of apoptosis using non-cytotoxic concentrations of the test compound against HTLV-1 positive and negative malignant cell lines. The anti-proliferative effect of lysine was established and confirmed by studying the effects of the test compound on the expression of TGF mRNA expression by RT-PCR. To investigate the effect of l-lysine on the induction of apoptosis, DNA flow cytometry analyses was done and the results verified by cell death ELISA. The results indicated that a significant increase in the preG(1) phase and a decrease in the S phase of the cell cycle in all of the ATL cells tested. l-Lysine up-regulated p53, p21, and Bax protein levels and a down-regulation of Bcl-2alpha in all the cell lines tested. l-Lysine was found to exert its effect through the NF-kappaB pathway by inhibiting the p65 subunit specifically. Also l-lysine caused a decrease in the levels MMP-2 and MMP-9 as well as their enzymatic activity.
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Affiliation(s)
- S Harakeh
- Biology Department, American University of Beirut, Beirut, Lebanon.
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35
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Di Lello P, Jenkins LMM, Jones TN, Nguyen BD, Hara T, Yamaguchi H, Dikeakos JD, Appella E, Legault P, Omichinski JG. Structure of the Tfb1/p53 complex: Insights into the interaction between the p62/Tfb1 subunit of TFIIH and the activation domain of p53. Mol Cell 2006; 22:731-740. [PMID: 16793543 DOI: 10.1016/j.molcel.2006.05.007] [Citation(s) in RCA: 165] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2006] [Revised: 04/21/2006] [Accepted: 05/03/2006] [Indexed: 10/24/2022]
Abstract
The interaction between the amino-terminal transactivation domain (TAD) of p53 and TFIIH is directly correlated with the ability of p53 to activate both transcription initiation and elongation. We have identified a region within the p53 TAD that specifically interacts with the pleckstrin homology (PH) domain of the p62 and Tfb1 subunits of human and yeast TFIIH. We have solved the 3D structure of a complex between the p53 TAD and the PH domain of Tfb1 by NMR spectroscopy. Our structure reveals that p53 forms a nine residue amphipathic alpha helix (residues 47-55) upon binding to Tfb1. In addition, we demonstrate that diphosphorylation of p53 at Ser46 and Thr55 leads to a significant enhancement in p53 binding to p62 and Tfb1. These results indicate that a phosphorylation cascade involving Ser46 and Thr55 of p53 could play an important role in the regulation of select p53 target genes.
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Affiliation(s)
- Paola Di Lello
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - Lisa M Miller Jenkins
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Tamara N Jones
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia 30602
| | - Bao D Nguyen
- Department of Chemistry, University of California, Irvine, California 92697
| | - Toshiaki Hara
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Hiroshi Yamaguchi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Jimmy D Dikeakos
- Laboratory of Molecular Biochemistry of Hypertension, Institut de Recherches Cliniques de Montréal, Montréal, Québec H2W 1R7, Canada
| | - Ettore Appella
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892
| | - Pascale Legault
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada
| | - James G Omichinski
- Département de Biochimie, Université de Montréal, Montréal, Québec H3C 3J7, Canada.
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36
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Borger DR, DeCaprio JA. Targeting of p300/CREB binding protein coactivators by simian virus 40 is mediated through p53. J Virol 2006; 80:4292-303. [PMID: 16611888 PMCID: PMC1472010 DOI: 10.1128/jvi.80.9.4292-4303.2006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The primary transforming functions of simian virus 40 large T antigen (SV40 LT) are conferred primarily through the binding and inactivation of p53 and the retinoblastoma family members. Normal p53 function requires an association with the CREB binding protein (CBP)/p300 coactivators, and a ternary complex containing SV40 LT, p53, and CBP/p300 has been identified previously. In this report, we have evaluated a secondary function of p53 bound to the SV40 LT complex in mediating the binding of human CBP/p300. We demonstrate that p53 associated with SV40 LT was posttranslationally modified in a manner consistent with the binding of CBP/p300. Furthermore, expression of SV40 LT induced the proportion of p53 phosphorylated on S15. An essential function for p53 in bridging the interaction between SV40 LT and CBP/p300 was identified through the reconstitution of the SV40 LT-CBP/p300 complex upon p53 reexpression in p53-null cells. In addition, the SV40 LT-CBP/p300 complex was disrupted through RNA interference-mediated depletion of endogenous p53. We also demonstrate that SV40 LT was acetylated in a p300- and p53-dependent manner, at least in part through the CH3 domain of p300. Therefore, the binding of p53 serves to modify SV40 LT by targeting CBP and p300 binding to direct the acetylation of SV40 LT.
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Affiliation(s)
- Darrell R Borger
- Dana-Farber Cancer Institute, Department of Medical Oncology, Harvard Medical School, Mayer Building 457, 44 Binney Street, Boston, Massachusetts 02115, USA
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37
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Park HU, Jeong SJ, Jeong JH, Chung JH, Brady JN. Human T-cell leukemia virus type 1 Tax attenuates gamma-irradiation-induced apoptosis through physical interaction with Chk2. Oncogene 2006; 25:438-47. [PMID: 16158050 DOI: 10.1038/sj.onc.1209059] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Checkpoint kinase 2 (Chk2) is known to mediate diverse cellular responses to genotoxic stress. The fundamental role of Chk2 is to regulate the network of genome-surveillance pathways that coordinate cell-cycle progression with DNA repair and cell survival or death. Defects in Chk2 contribute to the development of both hereditary and sporadic human cancers. We now present evidence that the human T-cell leukemia virus type-1 (HTLV-1) Tax protein directly interacts with Chk2 and the kinase activity of Chk2 is inhibited by Tax. The physical interaction of Chk2 and Tax was observed by co-immunoprecipitation assays in HTLV-1-infected T cells (C81) as well as GST pull-down assays using purified proteins. Binding and kinase activity inhibition studies with Tax deletion mutants indicated that at least two domains of Tax mediate the interaction with Chk2. We have analysed the functional consequence of de novo expression of Tax upon the cellular DNA-damage-induced apoptosis, which is mediated by Chk2. Using transient transfection and TUNEL assay, we found that gamma-irradiation-induced apoptosis was decreased in 293T and HCT-116 (p53(-/-)) cells expressing HTLV-1 Tax. Our studies demonstrate an important potential target of Tax in cellular transformation.
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Affiliation(s)
- H U Park
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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38
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Harakeh S, Diab-Assaf M, Niedzwiecki A, Khalife J, Abu-El-Ardat K, Rath M. Apoptosis induction by Epican Forte in HTLV-1 positive and negative malignant T-cells. Leuk Res 2006; 30:869-81. [PMID: 16427125 DOI: 10.1016/j.leukres.2005.11.027] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 11/24/2005] [Accepted: 11/29/2005] [Indexed: 11/25/2022]
Abstract
The effects of a novel nutrient formulation Epican Forte (EF) were evaluated on proliferation and induction of apoptosis using non-cytotoxic concentrations against HTLV-1 positive (HuT-102 & C91-PL) and negative (CEM & Jurkat) cells. EF showed anti-proliferative effect as determined by MTT assay and TGF mRNA protein expression using RT-PCR. EF resulted in the down-regulation of TGF-alpha and an up-regulation in TGF-beta2. EF caused a significant increase in apoptotic cells in the preG1 phase. These results were confirmed using Cell Death ELISA and Annexin V-FITC. Induction of apoptosis was caused by an up-regulation of p53, p21 and Bax protein levels and a down-regulation of Bcl-2alpha protein expression level.
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Affiliation(s)
- S Harakeh
- Department of Biology, American University of Beirut, Beirut, Lebanon.
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39
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Tabakin-Fix Y, Azran I, Schavinky-Khrapunsky Y, Levy O, Aboud M. Functional inactivation of p53 by human T-cell leukemia virus type 1 Tax protein: mechanisms and clinical implications. Carcinogenesis 2005; 27:673-81. [PMID: 16308315 DOI: 10.1093/carcin/bgi274] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-I) has been implicated with the etiology of adult T-cell leukemia (ATL) and certain other clinical disorders. Although the leukemogenic mechanism of HTLV-1 is not fully understood yet, the viral Tax protein is widely regarded as a key factor in this mechanism. Tax can modulate the synthesis or function of many regulatory factors which control a wide range of normal and oncogenic cellular processes and therefore, it acts as a potent oncoprotein. In the last few years, special attention has been attracted to Tax interference with the transactivation function of p53, a tumor-suppressor protein that is involved in regulation of the cell-cycle and apoptosis and in maintaining the cellular genome integrity. p53 is mutated in approximately 60% of all human tumors. In contrast, mutant p53 is found in only small percentage of ATL patients. Nevertheless, p53 is inactive in the leukemic cells of most ATL patients and in most HTLV-1 transformed cells. By inactivating p53, Tax can immortalize the HTLV-1-infected cells and destabilize their genome. Consequently, such cells can progress toward the ultimate leukemic state by a stepwise accumulation of oncogenic mutations and other types of chromosomal aberrations. Furthermore, since p53 exists in most ATL patients in its wild-type form, its reactivation by therapeutic drugs might be an effective approach for ATL therapy. Several mechanisms have been proposed so far for Tax-induced p53 inactivation. Understanding the exact mechanism of this Tax effect is essential for designing effective means for this therapeutic approach. In this review article, we discuss the various mechanisms proposed for Tax interference with p53 functions and their clinical and therapeutic implications.
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Affiliation(s)
- Yulia Tabakin-Fix
- Department of Microbiology and Immunology, Cancer Research Center, Faculty of Health Sciences and Department of Life Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
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40
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Awasthi S, Sharma A, Wong K, Zhang J, Matlock EF, Rogers L, Motloch P, Takemoto S, Taguchi H, Cole MD, Lüscher B, Dittrich O, Tagami H, Nakatani Y, McGee M, Girard AM, Gaughan L, Robson CN, Monnat RJ, Harrod R. A human T-cell lymphotropic virus type 1 enhancer of Myc transforming potential stabilizes Myc-TIP60 transcriptional interactions. Mol Cell Biol 2005; 25:6178-98. [PMID: 15988028 PMCID: PMC1168837 DOI: 10.1128/mcb.25.14.6178-6198.2005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human T-cell lymphotropic virus type 1 (HTLV-1) infects and transforms CD4+ lymphocytes and causes adult T-cell leukemia/lymphoma (ATLL), an aggressive lymphoproliferative disease that is often fatal. Here, we demonstrate that the HTLV-1 pX splice-variant p30II markedly enhances the transforming potential of Myc and transcriptionally activates the human cyclin D2 promoter, dependent upon its conserved Myc-responsive E-box enhancer elements, which are associated with increased S-phase entry and multinucleation. Enhancement of c-Myc transforming activity by HTLV-1 p30II is dependent upon the transcriptional coactivators, transforming transcriptional activator protein/p434 and TIP60, and it requires TIP60 histone acetyltransferase (HAT) activity and correlates with the stabilization of HTLV-1 p30II/Myc-TIP60 chromatin-remodeling complexes. The p30II oncoprotein colocalizes and coimmunoprecipitates with Myc-TIP60 complexes in cultured HTLV-1-infected ATLL patient lymphocytes. Amino acid residues 99 to 154 within HTLV-1 p30II interact with the TIP60 HAT, and p30II transcriptionally activates numerous cellular genes in a TIP60-dependent or TIP60-independent manner, as determined by microarray gene expression analyses. Importantly, these results suggest that p30II functions as a novel retroviral modulator of Myc-TIP60-transforming interactions that may contribute to adult T-cell leukemogenesis.
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Affiliation(s)
- Soumya Awasthi
- Laboratory of Molecular Virology, Department of Biological Sciences, Southern Methodist University, 334-DLS, 6501 Airline Drive, Dallas, TX 75275-0376.
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41
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Ma B, Pan Y, Gunasekaran K, Keskin O, Venkataraghavan RB, Levine AJ, Nussinov R. The contribution of the Trp/Met/Phe residues to physical interactions of p53 with cellular proteins. Phys Biol 2005; 2:S56-66. [PMID: 16204849 DOI: 10.1088/1478-3975/2/2/s06] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Dynamic molecular interaction networks underlie biological phenomena. Among the many genes which are involved, p53 plays a central role in networks controlling cellular life and death. It not only operates as a tumor suppressor, but also helps regulate hundreds of genes in response to various types of stress. To accomplish these functions as a guardian of the genome, p53 interacts extensively with both nucleic acids and proteins. This paper examines the physical interfaces of the p53 protein with cellular proteins. Previously, in the analysis of the structures of protein-protein complexes, we have observed that amino acids Trp, Met and Phe are important for protein-protein interactions in general. Here we show that these residues are critical for the many functions of p53. Several clusters of the Trp/Met/Phe residues are involved in the p53 protein-protein interactions. Phe19/Trp23 in the TA1 region extensively binds to the transcriptional factors and the MDM2 protein. Trp53/Phe54 in the TA2 region is crucial for transactivation and DNA replication. Met243 in the core domain interacts with 53BP1, 53BP2 and Rad 51 proteins. Met384/Phe385 in the C-terminal region interacts with the S100B protein and the Bromodomain of the CBP protein. Thus, these residues may assist in elucidating the p53 interactions when structural data are not available.
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Affiliation(s)
- Buyong Ma
- Basic Research Program, SAIC-Frederick, Inc., Laboratory of Experimental and Computational Biology, NCI-Frederick, Frederick, MD 21702, USA.
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42
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Wang J, Iwasaki H, Krivtsov A, Febbo PG, Thorner AR, Ernst P, Anastasiadou E, Kutok JL, Kogan SC, Zinkel SS, Fisher JK, Hess JL, Golub TR, Armstrong SA, Akashi K, Korsmeyer SJ. Conditional MLL-CBP targets GMP and models therapy-related myeloproliferative disease. EMBO J 2005; 24:368-81. [PMID: 15635450 PMCID: PMC545811 DOI: 10.1038/sj.emboj.7600521] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2004] [Accepted: 11/24/2004] [Indexed: 11/09/2022] Open
Abstract
Chromosomal translocations that fuse the mixed lineage leukemia (MLL) gene with multiple partners typify acute leukemias of infancy as well as therapy-related leukemias. We utilized a conditional knockin strategy to bypass the embryonic lethality caused by MLL-CBP expression and to assess the immediate effects of induced MLL-CBP expression on hematopoiesis. Within days of activating MLL-CBP, the fusion protein selectively expanded granulocyte/macrophage progenitors (GMP) and enhanced their self-renewal/proliferation. MLL-CBP altered the gene expression program of GMP, upregulating a subset of genes including Hox a9. Inhibition of Hox a9 expression by RNA interference demonstrated that MLL-CBP required Hox a9 for its enhanced cell expansion. Following exposure to sublethal gamma-irradiation or N-ethyl-N-nitrosourea (ENU), MLL-CBP mice developed myelomonocytic hyperplasia and progressed to fatal myeloproliferative disorders. These represented the spectrum of therapy-induced acute myelomonocytic leukemia/chronic myelomonocytic leukemia/myelodysplastic/myeloproliferative disorder similar to that seen in humans possessing the t(11;16). This model of MLL-CBP therapy-related myeloproliferative disease demonstrates the selectivity of this MLL fusion for GMP cells and its ability to initiate leukemogenesis in conjunction with cooperating mutations.
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Affiliation(s)
- Jing Wang
- Department of Pathology and Medicine, Howard Hughes Medical Institute, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Hiromi Iwasaki
- Department of Pathology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Andrei Krivtsov
- Division of Hematology/Oncology, Children's Hospital, Boston, MA, USA
| | - Phillip G Febbo
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Aaron R Thorner
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Patricia Ernst
- Department of Pathology and Medicine, Howard Hughes Medical Institute, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Ema Anastasiadou
- Harvard Institutes of Medicine, Harvard Medical School, Boston, MA, USA
| | - Jeffery L Kutok
- Department of Pathology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Scott C Kogan
- Comprehensive Cancer Center and Department of Laboratory Medicine, University of California, San Francisco, CA, USA
| | - Sandra S Zinkel
- Department of Pathology and Medicine, Howard Hughes Medical Institute, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Jill K Fisher
- Department of Pathology and Medicine, Howard Hughes Medical Institute, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
| | - Jay L Hess
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA
| | - Todd R Golub
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Scott A Armstrong
- Division of Hematology/Oncology, Children's Hospital, Boston, MA, USA
| | - Koichi Akashi
- Department of Pathology, Harvard Medical School, Dana-Farber Cancer Institute, Boston, MA, USA
| | - Stanley J Korsmeyer
- Department of Pathology and Medicine, Howard Hughes Medical Institute, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA
- Howard Hughes Medical Institute, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA. Tel.: +1 617 632 6402; Fax: +1 617 632 6401; E-mail:
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Matt T, Martinez-Yamout M, Dyson H, Wright P. The CBP/p300 TAZ1 domain in its native state is not a binding partner of MDM2. Biochem J 2004; 381:685-91. [PMID: 15154850 PMCID: PMC1133877 DOI: 10.1042/bj20040564] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2004] [Revised: 05/19/2004] [Accepted: 05/24/2004] [Indexed: 01/07/2023]
Abstract
The transcriptional co-activator CBP [CREB (cAMP-response-element-binding protein)-binding protein] and its paralogue p300 play a key role in the regulation of both activity and stability of the tumour suppressor p53. Degradation of p53 is mediated by the ubiquitin ligase MDM2 (mouse double minute protein) and is also reported to be regulated by CBP/p300. Direct protein-protein interaction between a central domain of MDM2 and the TAZ1 (transcriptional adaptor zinc-binding domain) [C/H1 (cysteine/histidine-rich region 1)] domain of p300 and subsequent formation of a ternary complex including p53 have been reported previously. We expressed and purified the proposed binding domains of HDM2 (human homologue of MDM2) and CBP, and examined their interactions using CD spectroscopy. The binding studies were extended by using natively purified GST (glutathione S-transferase)-p300 TAZ1 and GST-p53 fusion proteins, together with in vitro translated HDM2 fragments, under similar solution conditions to those in previous studies, but omitting added EDTA, which causes unfolding and aggregation of the zinc-binding TAZ1 domain. Comparing the binding properties of the known TAZ1 interaction partners HIF-1alpha (hypoxia-inducible factor 1), CITED2 (CBP/p300-interacting transactivator with glutamic- and aspartic-rich tail) and STAT2 (signal transducer and activator of transcription 2) with HDM2, our data suggest that TAZ1 in its native state does not serve as a specific recognition domain of HDM2. Rather, unfolded TAZ1 and HDM2 proteins have a high tendency to aggregate, and non-specific protein complexes are formed under certain conditions.
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Affiliation(s)
- Theresia Matt
- Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, U.S.A
| | - Maria A. Martinez-Yamout
- Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, U.S.A
| | - H. Jane Dyson
- Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, U.S.A
| | - Peter E. Wright
- Department of Molecular Biology and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, U.S.A
- To whom correspondence should be addressed (e-mail )
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Impey S, McCorkle SR, Cha-Molstad H, Dwyer JM, Yochum GS, Boss JM, McWeeney S, Dunn JJ, Mandel G, Goodman RH. Defining the CREB Regulon. Cell 2004; 119:1041-54. [PMID: 15620361 DOI: 10.1016/j.cell.2004.10.032] [Citation(s) in RCA: 397] [Impact Index Per Article: 19.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2004] [Revised: 09/14/2004] [Accepted: 10/13/2004] [Indexed: 10/26/2022]
Abstract
The CREB transcription factor regulates differentiation, survival, and synaptic plasticity. The complement of CREB targets responsible for these responses has not been identified, however. We developed a novel approach to identify CREB targets, termed serial analysis of chromatin occupancy (SACO), by combining chromatin immunoprecipitation (ChIP) with a modification of SAGE. Using a SACO library derived from rat PC12 cells, we identified approximately 41,000 genomic signature tags (GSTs) that mapped to unique genomic loci. CREB binding was confirmed for all loci supported by multiple GSTs. Of the 6302 loci identified by multiple GSTs, 40% were within 2 kb of the transcriptional start of an annotated gene, 49% were within 1 kb of a CpG island, and 72% were within 1 kb of a putative cAMP-response element (CRE). A large fraction of the SACO loci delineated bidirectional promoters and novel antisense transcripts. This study represents the most comprehensive definition of transcription factor binding sites in a metazoan species.
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Affiliation(s)
- Soren Impey
- Vollum Institute, Oregon Health and Science University, Portland, OR 97239, USA.
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Bayly R, Chuen L, Currie RA, Hyndman BD, Casselman R, Blobel GA, LeBrun DP. E2A-PBX1 interacts directly with the KIX domain of CBP/p300 in the induction of proliferation in primary hematopoietic cells. J Biol Chem 2004; 279:55362-71. [PMID: 15507449 DOI: 10.1074/jbc.m408654200] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The E2A gene encodes DNA-binding transcription factors, called E12 and E47, involved in cell specification and maturation. E2A is also involved in a chromosomal translocation that leads to the expression of an oncogenic transcription factor called E2A-PBX1 in cases of acute leukemia. In the work described here, we elucidate the interaction between E2A-PBX1 and transcriptional co-activators. We confirm that the E2A portion can interact with CBP and PCAF and map required elements on E2A and CBP. On CBP, the interaction involves the KIX domain, a well characterized domain that mediates interactions with several other oncogenic transcription factors. On E2A, the interaction with CBP requires conserved alpha-helical domains that reside within activation domains 1 and 2 (AD1 and AD2, respectively). Using purified, recombinant proteins, we show that the E2A-CBP interaction is direct. Notwithstanding the previously demonstrated ability of AD1 and AD2 to function independently, some of our findings suggest functional cooperativity between these two domains. Finally, we show that the CBP/p300-interactive helical domains of E2A are important in the induction of proliferation in cultured primary bone marrow cells retrovirally transduced with E2A-PBX1. Our findings suggest that some aspects of E2A-PBX1 oncogenesis involve a direct interaction with the KIX domain of CBP/p300.
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Affiliation(s)
- Richard Bayly
- Queen's University Cancer Research Institute, Department of Pathology and Molecular Medicine, Queen's University, Kingston, Ontario, K7L 3N6, Canada
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Harakeh S, Diab-Assef M, El-Sabban M, Haddadin M, Gali-Muhtasib H. Inhibition of proliferation and induction of apoptosis by 2-benzoyl-3-phenyl-6,7-dichloroquinoxaline 1,4-dioxide in adult T-cell leukemia cells. Chem Biol Interact 2004; 148:101-13. [PMID: 15276867 DOI: 10.1016/j.cbi.2004.05.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2003] [Revised: 05/07/2004] [Accepted: 05/19/2004] [Indexed: 11/15/2022]
Abstract
Human T-cell lymphotrophic virus type-1 (HTLV-1) is a retrovirus which causes adult T-cell leukemia (ATL), an aggressive malignancy of activated T-cells. So far, there is no proven therapy for this disease. The compound 2-benzoyl-3-phenyl-6,7-dichloro quinoxaline 1,4-dioxide (DCQ) has been shown to exhibit a wide range of antibacterial activities and to induce antiproliferation and apoptosis of human colon cancer cell lines. In the present study, we investigated the in vitro effects of DCQ in HTLV-1 positive (C91-PL and HuT-102) and negative (CEM and Jurkat) malignant T-cells. The results indicate that DCQ induced growth inhibition in all four cell lines examined in a dose-dependent manner. The inhibitory effect was mainly due to the induction of apoptosis which was verified by flow cytometry analyses and ELISA-based apoptosis assays. The role of transforming growth factor (TGF) in mediating the antiproliferative and apoptotic effects of DCQ in ATL cells was investigated. Interestingly, in three of the four cell lines used, DCQ increased the TGF-beta1 transcript levels and decreased TGF-alpha mRNA, but did not induce changes in TGF-beta2 expression. DCQ treatment also induced an upregulation of p53 and p21 protein levels, key mediators of cell cycle arrest and apoptosis. The anti-apoptotic Bcl-2alpha protein level was found to be reduced. These findings indicate that DCQ inhibits the growth of ATL cell lines, at least in part, by inducing apoptosis mediated by the modulation of TGF expression, the upregulation in p53 and p21 proteins and downregulation in Bcl-2alpha expression. The present findings suggest that DCQ merits further investigation as a potential therapeutic agent for this incurable disease.
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Affiliation(s)
- Steve Harakeh
- Biology Department, American University of Beirut, Lebanon.
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47
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Jeong SJ, Radonovich M, Brady JN, Pise-Masison CA. HTLV-I Tax induces a novel interaction between p65/RelA and p53 that results in inhibition of p53 transcriptional activity. Blood 2004; 104:1490-7. [PMID: 15155458 DOI: 10.1182/blood-2003-12-4174] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Nuclear factor kappaB (NF-kappaB) activation plays a critical role in oncogenesis by human T-cell lymphotrophic virus type I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL), and is indispensable for maintenance of the malignant phenotype. In T lymphocytes, Tax-mediated p53 inhibition is dependent on Tax activation of the NF-kappaB pathway and is linked to p53 phosphorylation. We now report that blocking NF-kappaB transcriptional activation in HTLV-I-transformed cells restores p53 activity. Further, using mouse embryo fibroblast (MEF) null cells and antisense oligonucleotides to inhibit expression of NF-kappaB family members, we demonstrate that the p65 subunit of NF-kappaB is uniquely involved in p53 inhibition. Coimmunoprecipitation assays demonstrate an interaction between p65 and p53 in HTLV-I-transformed cells. In transient transfection assays, we demonstrate that Tax induces the p53-p65 interaction. Phosphorylation of p53 at serines 15 and 392 is critical for complex formation. Importantly, Tax-mediated p53 inhibition correlates with p65 and p53 interaction. By using chromatin immunoprecipitation (ChIP) assays, we find that in HTLV-I-transformed cells p53 and p65 form a complex on the inactive, p53-responsive murine double minute 2 (MDM2) promoter. Consistent with reduced transcriptional activity, transcription factor IID (TFIID) binding is not observed. These studies identify a unique mechanism for p53 regulation by the p65/RelA subunit of NF-kappaB.
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Affiliation(s)
- Soo-Jin Jeong
- Virus Tumor Biology Section, Basic Research Laboratory, Center for Cancer Research, National Cancer Institute/NIH, Bldg 41/B303, 41 Library Drive, Bethesda, MD 20892, USA
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Grönroos E, Terentiev AA, Punga T, Ericsson J. YY1 inhibits the activation of the p53 tumor suppressor in response to genotoxic stress. Proc Natl Acad Sci U S A 2004; 101:12165-70. [PMID: 15295102 PMCID: PMC514451 DOI: 10.1073/pnas.0402283101] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The tumor suppressor p53 regulates cell-cycle progression and apoptosis in response to genotoxic stress, and inactivation of p53 is a common feature of cancer cells. The levels and activity of p53 are tightly regulated by posttranslational modifications, including phosphorylation, ubiquitination, and acetylation. Here, we demonstrate that the transcription factor Yin Yang 1 (YY1) interacts with p53 and inhibits its transcriptional activity. We show that YY1 disrupts the interaction between p53 and the coactivator p300 and that expression of YY1 blocks p300-dependent acetylation and stabilization of p53. Furthermore, expression of YY1 inhibits the accumulation of p53 and the induction of p53 target genes in response to genotoxic stress. YY1 also interacts with Mdm2 and the expression of YY1 promotes the assembly of the p53-Mdm2 complex. Consequently, YY1 enhances Mdm2-mediated ubiquitination of p53. Inactivation of endogenous YY1 enhances the accumulation of p53 as well as the expression of p53 target genes in response to DNA damage, and it sensitizes cells to DNA damage-induced apoptosis. Hence, our results demonstrate that YY1 regulates the transcriptional activity, acetylation, ubiquitination, and stability of p53 by inhibiting its interaction with the coactivator p300 and by enhancing its interaction with the negative regulator Mdm2. YY1 may, therefore, be an important negative regulator of the p53 tumor suppressor in response to genotoxic stress.
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Affiliation(s)
- Eva Grönroos
- Biomedical Center, Ludwig Institute for Cancer Research, Box 595, Husargatan 3, S-751 24 Uppsala, Sweden
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Park HU, Jeong JH, Chung JH, Brady JN. Human T-cell leukemia virus type 1 Tax interacts with Chk1 and attenuates DNA-damage induced G2 arrest mediated by Chk1. Oncogene 2004; 23:4966-74. [PMID: 15107832 DOI: 10.1038/sj.onc.1207644] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Checkpoint kinase 1 (Chk1) mediates diverse cellular responses to genotoxic stress, regulating the network of genome-surveillance pathways that coordinate cell cycle progression with DNA repair. Chk1 is essential for mammalian development and viability, and has been shown to be important for both S and G(2) checkpoints. We now present evidence that the HTLV-1 Tax protein interacts directly with Chk1 and impairs its kinase activities in vitro and in vivo. The direct and physical interaction of Chk1 and Tax was observed in HTLV-1-infected T cells (C81, HuT 102 and MT-2) and transfected fibroblasts (293 T) by coimmunoprecipitation and by in vitro GST pull-down assays. Interestingly, Tax inhibited the kinase activity of Chk1 protein in in vitro and in vivo kinase assays. Consistent with these results, Tax inhibited the phosphorylation-dependent degradation of Cdc25A and G(2) arrest in response to gamma-irradiation (IR) in a dose-dependent manner in vivo. The G(2) arrest did not require Chk2 or p53. These studies provide the first example of a viral transforming protein targeting Chk1 and provide important insights into checkpoint pathway regulation.
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Affiliation(s)
- Hyeon Ung Park
- Virus Tumor Biology Section, Laboratory of Cellular Oncology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Scian MJ, Stagliano KER, Deb D, Ellis MA, Carchman EH, Das A, Valerie K, Deb SP, Deb S. Tumor-derived p53 mutants induce oncogenesis by transactivating growth-promoting genes. Oncogene 2004; 23:4430-43. [PMID: 15077194 DOI: 10.1038/sj.onc.1207553] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have studied the mechanism of mutant p53-mediated oncogenesis using several tumor-derived mutants. Using a colony formation assay, we found that the majority of the mutants increased the number of colonies formed compared to the vector. Expression of tumor-derived p53 mutants increases the rate of cell growth, suggesting that the p53 mutants have 'gain of function' properties. We have studied the gene expression profile of cells expressing tumor-derived p53-D281G to identify genes transactivated by mutant p53. We report the transactivation of two genes, asparagine synthetase and human telomerase reverse transcriptase. Quantitative real-time PCR confirms this upregulation. Transient transfection promoter assays verify that tumor-derived p53 mutants transactivate these promoters significantly. An electrophoretic mobility shift assay shows that tumor-derived p53-mutants cannot bind to the wild-type p53 consensus sequence. The results presented here provide some evidence of a possible mechanism for mutant p53-mediated transactivation.
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Affiliation(s)
- Mariano J Scian
- Department of Biochemistry and the Massey Cancer Center, Virginia Commonwealth University, PO Box 980614, Richmond, VA 23298, USA
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