1
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Li H, Zou F, Zhang J, Zhu S, Chu K, Zhang X, Zhao T. YAP suppresses human T-cell leukemia virus type 1 transcription. J Med Virol 2023; 95:e29065. [PMID: 37661566 DOI: 10.1002/jmv.29065] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 08/11/2023] [Accepted: 08/17/2023] [Indexed: 09/05/2023]
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is an oncogenic retrovirus that causes adult T-cell leukemia/lymphoma (ATL). HTLV-1 encodes Tax protein that activates transcription from viral long terminal repeats (LTR). Multiple cofactors are involved in the regulation of HTLV-1 transcription via association with Tax. Yes-associated protein (YAP), which is the key effector of Hippo pathway, is elevated and activated in ATL cells. In this study, we reported that YAP protein suppressed Tax activation of HTLV-1 5' LTR but not 3' LTR. The activation of the 5' LTR by Tax was potentiated when YAP was depleted. Moreover, overexpression of YAP repressed HTLV-1 plus-strand viral gene expression and virion production, whereas compromising YAP by RNA inference augmented the expression of HTLV-1 protein. As mechanisms of YAP-mediated viral transcription inhibition, we found that YAP interacted with Tax, and prevented the association between Tax and p300. It finally led to the inhibition of recruitment of Tax to the Tax-responsive element in the 5' LTR of HTLV-1. Taken together, our results demonstrate the negative regulatory function of YAP in Tax activation of HTLV-1 transcription. It may achieve sufficient transcriptional repression to maintain persistent infection and long-term latency of HTLV-1 in the host cells.
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Affiliation(s)
- Hengbo Li
- School of Medicine, Hangzhou City University, Hangzhou, China
- College of Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Feng Zou
- College of Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Jie Zhang
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Shengyu Zhu
- School of Medicine, Hangzhou City University, Hangzhou, China
| | - Kaifei Chu
- School of Medicine, Hangzhou City University, Hangzhou, China
- College of Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Xu Zhang
- School of Medicine, Hangzhou City University, Hangzhou, China
- College of Life Sciences, Zhejiang Normal University, Jinhua, China
| | - Tiejun Zhao
- School of Medicine, Hangzhou City University, Hangzhou, China
- College of Life Sciences, Zhejiang Normal University, Jinhua, China
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2
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Kendle W, Hoang K, Korleski E, Panfil AR, Polakowski N, Lemasson I. Upregulation of Neuropilin-1 Inhibits HTLV-1 Infection. Pathogens 2023; 12:831. [PMID: 37375521 DOI: 10.3390/pathogens12060831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/09/2023] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
Infection with human T-cell leukemia virus type 1 (HTLV-1) can produce a spectrum of pathological effects ranging from inflammatory disorders to leukemia. In vivo, HTLV-1 predominantly infects CD4+ T-cells. Infectious spread within this population involves the transfer of HTLV-1 virus particles from infected cells to target cells only upon cell-to-cell contact. The viral protein, HBZ, was found to enhance HTLV-1 infection through transcriptional activation of ICAM1 and MYOF, two genes that facilitate viral infection. In this study, we found that HBZ upregulates the transcription of COL4A1, GEM, and NRP1. COL4A1 and GEM are genes involved in viral infection, while NRP1, which encodes neuropilin 1 (Nrp1), serves as an HTLV-1 receptor on target cells but has no reported function on HTLV-1-infected cells. With a focus on Nrp1, cumulative results from chromatin immunoprecipitation assays and analyses of HBZ mutants support a model in which HBZ upregulates NRP1 transcription by augmenting recruitment of Jun proteins to an enhancer downstream of the gene. Results from in vitro infection assays demonstrate that Nrp1 expressed on HTLV-1-infected cells inhibits viral infection. Nrp1 was found to be incorporated into HTLV-1 virions, and deletion of its ectodomain removed the inhibitory effect. These results suggest that inhibition of HTLV-1 infection by Nrp1 is caused by the ectodomain of Nrp1 extended from virus particles, which may inhibit the binding of virus particles to target cells. While HBZ has been found to enhance HTLV-1 infection using cell-based models, there may be certain circumstances in which activation of Nrp1 expression negatively impacts viral infection, which is discussed.
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Affiliation(s)
- Wesley Kendle
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Kimson Hoang
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Erica Korleski
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Amanda R Panfil
- Center for Retrovirus Research, Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - Nicholas Polakowski
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
| | - Isabelle Lemasson
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA
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3
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Polakowski N, Sarker MAK, Hoang K, Boateng G, Rushing AW, Kendle W, Pique C, Green PL, Panfil AR, Lemasson I. HBZ upregulates myoferlin expression to facilitate HTLV-1 infection. PLoS Pathog 2023; 19:e1011202. [PMID: 36827461 PMCID: PMC9994761 DOI: 10.1371/journal.ppat.1011202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/08/2023] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
The complex retrovirus, human T-cell leukemia virus type 1 (HTLV-1), primarily infects CD4+ T-cells in vivo. Infectious spread within this cell population requires direct contact between virally-infected and target cells. The HTLV-1 accessory protein, HBZ, was recently shown to enhance HTLV-1 infection by activating intracellular adhesion molecule 1 (ICAM-1) expression, which promotes binding of infected cells to target cells and facilitates formation of a virological synapse. In this study we show that HBZ additionally enhances HTLV-1 infection by activating expression of myoferlin (MyoF), which functions in membrane fusion and repair and vesicle transport. Results from ChIP assays and quantitative reverse transcriptase PCR indicate that HBZ forms a complex with c-Jun or JunB at two enhancer sites within the MYOF gene and activates transcription through recruitment of the coactivator p300/CBP. In HTLV-1-infected T-cells, specific inhibition of MyoF using the drug, WJ460, or shRNA-mediated knockdown of MyoF reduced infection efficiency. This effect was associated with a decrease in cell adhesion and an intracellular reduction in the abundance of HTLV-1 envelope (Env) surface unit (SU) and transmembrane domain (TM). Lysosomal protease inhibitors partially restored SU levels in WJ460-treated cells, and SU localization to LAMP-2 sites was increased by MyoF knockdown, suggesting that MyoF restricts SU trafficking to lysosomes for degradation. Consistent with these effects, less SU was associated with cell-free virus particles. Together, these data suggest that MyoF contributes to HTLV-1 infection through modulation of Env trafficking and cell adhesion.
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Affiliation(s)
- Nicholas Polakowski
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
| | - Md Abu Kawsar Sarker
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
| | - Kimson Hoang
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
| | - Georgina Boateng
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
| | - Amanda W. Rushing
- Catawba College, Department of Biology, Salisbury, North Carolina, United States of America
| | - Wesley Kendle
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
| | - Claudine Pique
- INSERM, U1016, Institut Cochin, Paris, France
- CNRS, UMR8104, Paris, France
- Université Paris Descartes, Sorbonne Paris Cité, Paris, France
| | - Patrick L. Green
- Center for Retrovirus Research and Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Amanda R. Panfil
- Center for Retrovirus Research and Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio, United States of America
| | - Isabelle Lemasson
- Brody School of Medicine, Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United States of America
- * E-mail:
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4
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D’Agostino DM, Raimondi V, Silic-Benussi M, Ciminale V. MiR-150 in HTLV-1-infection and T-cell transformation. Front Immunol 2022; 13:974088. [PMID: 36072598 PMCID: PMC9442802 DOI: 10.3389/fimmu.2022.974088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 07/25/2022] [Indexed: 11/18/2022] Open
Abstract
Human T-cell leukemia virus-1 (HTLV-1) is a retrovirus that persistently infects CD4+ T-cells, and is the causative agent of adult T-cell leukemia/lymphoma (ATLL), tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM) and several inflammatory diseases. T-cell transformation by HTLV-1 is driven by multiple interactions between viral regulatory proteins and host cell pathways that govern cell proliferation and survival. Studies performed over the last decade have revealed alterations in the expression of many microRNAs in HTLV-1-infected cells and ATLL cells, and have identified several microRNA targets with roles in the viral life cycle and host cell turnover. This review centers on miR-150-5p, a microRNA whose expression is temporally regulated during lymphocyte development and altered in several hematological malignancies. The levels of miR-150-5p are reduced in many HTLV-1-transformed- and ATLL-derived cell lines. Experiments in these cell lines showed that downregulation of miR-150-5p results in activation of the transcription factor STAT1, which is a direct target of the miRNA. However, data on miR-150-5p levels in freshly isolated ATLL samples are suggestive of its upregulation compared to controls. These apparently puzzling findings highlight the need for more in-depth studies of the role of miR-150-5p in HTLV-1 infection and pathogenesis based on knowledge of miR-150-5p-target mRNA interactions and mechanisms regulating its function in normal leukocytes and hematologic neoplasms.
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Affiliation(s)
- Donna M. D’Agostino
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Istituto Oncologico Veneto (IOV)- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Padova, Italy
- *Correspondence: Donna M. D’Agostino, ; Vincenzo Ciminale,
| | - Vittoria Raimondi
- Department of Surgery, Oncology and Gastroenterology, University of Padova, Padova, Italy
| | - Micol Silic-Benussi
- Istituto Oncologico Veneto (IOV)- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Padova, Italy
| | - Vincenzo Ciminale
- Istituto Oncologico Veneto (IOV)- Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Padova, Italy
- Department of Surgery, Oncology and Gastroenterology, University of Padova, Padova, Italy
- *Correspondence: Donna M. D’Agostino, ; Vincenzo Ciminale,
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5
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Forlani G, Shallak M, Accolla RS, Romanelli MG. HTLV-1 Infection and Pathogenesis: New Insights from Cellular and Animal Models. Int J Mol Sci 2021; 22:ijms22158001. [PMID: 34360767 PMCID: PMC8347336 DOI: 10.3390/ijms22158001] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 07/22/2021] [Accepted: 07/24/2021] [Indexed: 12/12/2022] Open
Abstract
Since the discovery of the human T-cell leukemia virus-1 (HTLV-1), cellular and animal models have provided invaluable contributions in the knowledge of viral infection, transmission and progression of HTLV-associated diseases. HTLV-1 is the causative agent of the aggressive adult T-cell leukemia/lymphoma and inflammatory diseases such as the HTLV-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). Cell models contribute to defining the role of HTLV proteins, as well as the mechanisms of cell-to-cell transmission of the virus. Otherwise, selected and engineered animal models are currently applied to recapitulate in vivo the HTLV-1 associated pathogenesis and to verify the effectiveness of viral therapy and host immune response. Here we review the current cell models for studying virus–host interaction, cellular restriction factors and cell pathway deregulation mediated by HTLV products. We recapitulate the most effective animal models applied to investigate the pathogenesis of HTLV-1-associated diseases such as transgenic and humanized mice, rabbit and monkey models. Finally, we summarize the studies on STLV and BLV, two closely related HTLV-1 viruses in animals. The most recent anticancer and HAM/TSP therapies are also discussed in view of the most reliable experimental models that may accelerate the translation from the experimental findings to effective therapies in infected patients.
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Affiliation(s)
- Greta Forlani
- Laboratory of General Pathology and Immunology “Giovanna Tosi”, Department of Medicine and Surgery, University of Insubria, 21100 Varese, Italy; (G.F.); (M.S.); (R.S.A.)
| | - Mariam Shallak
- Laboratory of General Pathology and Immunology “Giovanna Tosi”, Department of Medicine and Surgery, University of Insubria, 21100 Varese, Italy; (G.F.); (M.S.); (R.S.A.)
| | - Roberto Sergio Accolla
- Laboratory of General Pathology and Immunology “Giovanna Tosi”, Department of Medicine and Surgery, University of Insubria, 21100 Varese, Italy; (G.F.); (M.S.); (R.S.A.)
| | - Maria Grazia Romanelli
- Department of Biosciences, Biomedicine and Movement Sciences, University of Verona, 37134 Verona, Italy
- Correspondence:
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6
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The splice 1 variant of HTLV-1 bZIP factor stabilizes c-Jun. Virology 2020; 549:51-58. [PMID: 32841759 DOI: 10.1016/j.virol.2020.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 07/15/2020] [Accepted: 07/19/2020] [Indexed: 11/24/2022]
Abstract
HBZ is expressed by the complex retrovirus, Human T-cell Leukemia Virus type 1, and implicated in pathological effects associated with viral infection. From the nucleus, HBZ alters gene expression by interacting with a variety of transcriptional regulatory proteins, among which is c-Jun. Previously, one of the three HBZ variants, HBZUS, was reported to decrease c-Jun expression by promoting its degradation. Here we show that another variant, HBZS1, produces the opposite effect. In the presence of HBZS1, c-Jun expression increases due to its stabilization. Our data suggest that this effect requires the ability of HBZS1 to interact with c-Jun. We provide evidence that HBZS1 inhibits the proteosomal degradation of c-Jun initiated by the Cop1-containing ubiquitin ligase complex. HBZS1 is the most abundant variant in HTLV-1-infected T-cells, and our data indicate that levels of c-Jun expression in infected cells are consistent with effects of HBZS1.
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7
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Stolz ML, McCormick C. The bZIP Proteins of Oncogenic Viruses. Viruses 2020; 12:v12070757. [PMID: 32674309 PMCID: PMC7412551 DOI: 10.3390/v12070757] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 12/20/2022] Open
Abstract
Basic leucine zipper (bZIP) transcription factors (TFs) govern diverse cellular processes and cell fate decisions. The hallmark of the leucine zipper domain is the heptad repeat, with leucine residues at every seventh position in the domain. These leucine residues enable homo- and heterodimerization between ZIP domain α-helices, generating coiled-coil structures that stabilize interactions between adjacent DNA-binding domains and target DNA substrates. Several cancer-causing viruses encode viral bZIP TFs, including human T-cell leukemia virus (HTLV), hepatitis C virus (HCV) and the herpesviruses Marek’s disease virus (MDV), Epstein–Barr virus (EBV) and Kaposi’s sarcoma-associated herpesvirus (KSHV). Here, we provide a comprehensive review of these viral bZIP TFs and their impact on viral replication, host cell responses and cell fate.
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8
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Chu WT, Shammas SL, Wang J. Charge Interactions Modulate the Encounter Complex Ensemble of Two Differently Charged Disordered Protein Partners of KIX. J Chem Theory Comput 2020; 16:3856-3868. [PMID: 32325001 DOI: 10.1021/acs.jctc.9b01264] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Disordered proteins play important roles in cell signaling and are frequently involved in protein-protein interactions. They also have a larger proportion of charged and polar residues than their folded counterparts. Here, we developed a structure-based model and applied molecular dynamics simulations to examine the presence and importance of electrostatic interactions in the binding processes of two differently charged intrinsically disordered ligands of the KIX domain of CBP. We observed non-native opposite-charged contacts in the encounter complexes for both ligands with KIX, and this may be a general feature of coupled folding and binding reactions. The ensemble of successful encounter complexes is a diverse set of structures, and in the case of the highly charged ligand, this ensemble was found to be malleable with respect to ionic strength. There are only minor differences between encounter complex ensembles for successful and unsuccessful collisions with no key interactions that appear to make the process far more productive. The energy landscape at this early stage in the process does not appear highly funneled. Strikingly we observed many native interactions that appear to reduce chances of an encounter complex being productive. Instead it appears that collectively non-native electrostatic interactions in the encounter complex increase the likelihood of productivity by holding the proteins together long enough for folding to take place. This mechanism is more effective for the more highly charged ligand.
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Affiliation(s)
- Wen-Ting Chu
- State Key Laboratory of Electroanalytical Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, P.R.China
| | - Sarah L Shammas
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Jin Wang
- Department of Chemistry & Physics, State University of New York at Stony Brook, Stony Brook, New York 11794, United States
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9
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Martinez MP, Al-Saleem J, Green PL. Comparative virology of HTLV-1 and HTLV-2. Retrovirology 2019; 16:21. [PMID: 31391116 PMCID: PMC6686503 DOI: 10.1186/s12977-019-0483-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Accepted: 08/01/2019] [Indexed: 12/22/2022] Open
Abstract
Human T cell leukemia virus type 1 (HTLV-1) was the first discovered human retrovirus and the etiologic agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Shortly after the discovery of HTLV-1, human T-cell leukemia virus type 2 (HTLV-2) was isolated from a patient with hairy cell leukemia. Despite possession of similar structural features to HTLV-1, HTLV-2 has not been definitively associated with lymphoproliferative disease. Since their discovery, studies have been performed with the goal of highlighting the differences between HTLV-1 and HTLV-2. A better understanding of these differences will shed light on the specific pathogenic mechanisms of HTLV-1 and lead to novel therapeutic targets. This review will compare and contrast the two oldest human retroviruses with regards to epidemiology, genomic structure, gene products, and pathobiology.
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Affiliation(s)
- Michael P Martinez
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA.,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Jacob Al-Saleem
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA.,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA
| | - Patrick L Green
- Center for Retrovirus Research, The Ohio State University, Columbus, OH, USA. .,Department of Veterinary Biosciences, The Ohio State University, Columbus, OH, USA. .,Comprehensive Cancer Center, The Ohio State University, Columbus, OH, USA.
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10
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Lyngdoh D, Shukla H, Sonkar A, Anupam R, Tripathi T. Portrait of the Intrinsically Disordered Side of the HTLV-1 Proteome. ACS OMEGA 2019; 4:10003-10018. [PMID: 31460093 PMCID: PMC6648719 DOI: 10.1021/acsomega.9b01017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 05/28/2019] [Indexed: 05/07/2023]
Abstract
Intrinsically disordered proteins (IDPs) lack an ordered 3D structure. These proteins contain one or more intrinsically disordered protein regions (IDPRs). IDPRs interact promiscuously with other proteins, which leads to their structural transition from a disordered to an ordered state. Such interaction-prone regions of IDPs are known as molecular recognition features. Recent studies suggest that IDPs provide structural plasticity and functional diversity to viral proteins that are involved in rapid replication and immune evasion within the host cells. In the present study, we evaluated the prevalence of IDPs and IDPRs in human T lymphotropic virus type 1 (HTLV-1) proteome. We also investigated the presence of MoRF regions in the structural and nonstructural proteins of HTLV-1. We found abundant IDPRs in HTLV-1 bZIP factor, p30, Rex, and structural nucleocapsid p15 proteins, which are involved in diverse functions such as virus proliferation, mRNA export, and genomic RNA binding. Our study analyzed the HTLV-1 proteome with the perspective of intrinsic disorder identification. We propose that the intrinsic disorder analysis of HTLV-1 proteins may form the basis for the development of protein disorder-based drugs.
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Affiliation(s)
- Denzelle
L. Lyngdoh
- Molecular
and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India
| | - Harish Shukla
- Molecular
and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India
| | - Amit Sonkar
- Molecular
and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India
| | - Rajaneesh Anupam
- Department
of Biotechnology, Dr. Harisingh Gour Central
University, Sagar 470003, India
| | - Timir Tripathi
- Molecular
and Structural Biophysics Laboratory, Department of Biochemistry, North-Eastern Hill University, Shillong 793022, India
- E-mail: , . Phone: +91-364-2722141. Fax: +91-364-2550108
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11
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Rushing AW, Rushing B, Hoang K, Sanders SV, Péloponèse JM, Polakowski N, Lemasson I. HTLV-1 basic leucine zipper factor protects cells from oxidative stress by upregulating expression of Heme Oxygenase I. PLoS Pathog 2019; 15:e1007922. [PMID: 31251786 PMCID: PMC6623464 DOI: 10.1371/journal.ppat.1007922] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Revised: 07/11/2019] [Accepted: 06/18/2019] [Indexed: 12/18/2022] Open
Abstract
Adult T-cell Leukemia (ATL) is a lymphoproliferative disease of CD4+ T-cells infected with Human T-cell Leukemia Virus type I (HTLV-1). With the exception of allogeneic hematopoietic stem cell transplantation, there are no effective treatments to cure ATL, and ATL cells often acquire resistance to conventional chemotherapeutic agents. Accumulating evidence shows that development and maintenance of ATL requires key contributions from the viral protein, HTLV-1 basic leucine zipper factor (HBZ). In this study we found that HBZ activates expression of Heme Oxygenase 1 (HMOX-1), a component of the oxidative stress response that functions to detoxify free heme. Transcription of HMOX1 and other antioxidant genes is regulated by the small Mafs. These cellular basic leucine zipper (bZIP) factors control transcription by forming homo- or heterodimers among themselves or with other cellular bZIP factors that then bind Maf responsive elements (MAREs) in promoters or enhancers of antioxidant genes. Our data support a model in which HBZ activates HMOX1 transcription by forming heterodimers with the small Mafs that bind MAREs located in an upstream enhancer region. Consistent with this model, we found that HMOX-1 is upregulated in HTLV-1-transformed T-cell lines and confers these cells with resistance to heme-induced cytotoxicity. In this context, HBZ-mediated activation of HMOX-1 expression may contribute to resistance of ATL cells to certain chemotherapeutic agents. We also provide evidence that HBZ counteracts oxidative stress caused by two other HTLV-1-encoded proteins, Tax and p13. Tax induces oxidative stress as a byproduct of driving mitotic expansion of infected cells, and p13 is believed to induce oxidative stress to eliminate infected cells that have become transformed. Therefore, in this context, HBZ-mediated activation of HMOX-1 expression may facilitate transformation. Overall, this study characterizes a novel function of HBZ that may support the development and maintenance of ATL.
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Affiliation(s)
- Amanda W. Rushing
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
- * E-mail: (AWR); (IL)
| | - Blake Rushing
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Kimson Hoang
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Stephanie V. Sanders
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Jean-Marie Péloponèse
- Institut de Recherche en Infectiologie de Montpellier, Centre National de la Recherche Scientifique, Université de Montpellier, Montpellier, France
| | - Nicholas Polakowski
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
| | - Isabelle Lemasson
- Department of Microbiology and Immunology, Brody School of Medicine, East Carolina University, Greenville, North Carolina, United States of America
- * E-mail: (AWR); (IL)
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12
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Structural basis for cooperative regulation of KIX-mediated transcription pathways by the HTLV-1 HBZ activation domain. Proc Natl Acad Sci U S A 2018; 115:10040-10045. [PMID: 30232260 DOI: 10.1073/pnas.1810397115] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The human T cell leukemia virus I basic leucine zipper protein (HTLV-1 HBZ) maintains chronic viral infection and promotes leukemogenesis through poorly understood mechanisms involving interactions with the KIX domain of the transcriptional coactivator CBP and its paralog p300. The KIX domain binds regulatory proteins at the distinct MLL and c-Myb/pKID sites to form binary or ternary complexes. The intrinsically disordered N-terminal activation domain of HBZ (HBZ AD) deregulates cellular signaling pathways by competing directly with cellular and viral transcription factors for binding to the MLL site and by allosterically perturbing binding of the transactivation domain of the hematopoietic transcription factor c-Myb. Crystal structures of the ternary KIX:c-Myb:HBZ complex show that the HBZ AD recruits two KIX:c-Myb entities through tandem amphipathic motifs (L/V)(V/L)DGLL and folds into a long α-helix upon binding. Isothermal titration calorimetry reveals strong cooperativity in binding of the c-Myb activation domain to the KIX:HBZ complex and in binding of HBZ to the KIX:c-Myb complex. In addition, binding of KIX to the two HBZ (V/L)DGLL motifs is cooperative; the structures suggest that this cooperativity is achieved through propagation of the HBZ α-helix beyond the first binding motif. Our study suggests that the unique structural flexibility and the multiple interaction motifs of the intrinsically disordered HBZ AD are responsible for its potency in hijacking KIX-mediated transcription pathways. The KIX:c-Myb:HBZ complex provides an example of cooperative stabilization in a transcription factor:coactivator network and gives insights into potential mechanisms through which HBZ dysregulates hematopoietic transcriptional programs and promotes T cell proliferation.
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The Human T-Cell Leukemia Virus Type 1 Basic Leucine Zipper Factor Attenuates Repair of Double-Stranded DNA Breaks via Nonhomologous End Joining. J Virol 2018; 92:JVI.00672-18. [PMID: 29769340 DOI: 10.1128/jvi.00672-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 05/10/2018] [Indexed: 12/27/2022] Open
Abstract
Adult T-cell leukemia (ATL) is a fatal malignancy of CD4+ T cells infected with human T-cell leukemia virus type 1 (HTLV-1). ATL cells often exhibit random gross chromosomal rearrangements that are associated with the induction and improper repair of double-stranded DNA breaks (DSBs). The viral oncoprotein Tax has been reported to impair DSB repair but has not been shown to be consistently expressed throughout all phases of infection. The viral oncoprotein HTLV-1 basic leucine zipper (bZIP) factor (HBZ) is consistently expressed prior to and throughout disease progression, but it is unclear whether it also influences DSB repair. We report that HBZ attenuates DSB repair by nonhomologous end joining (NHEJ), in a manner dependent upon the bZIP domain. HBZ was found to interact with two vital members of the NHEJ core machinery, Ku70 and Ku80, and to be recruited to DSBs in a bZIP-dependent manner in vitro We observed that HBZ expression also resulted in a bZIP-dependent delay in DNA protein kinase (DNA-PK) activation following treatment with etoposide. Although Tax is reported to interact with Ku70, we did not find Tax expression to interfere with HBZ:Ku complex formation. However, as Tax was reported to saturate NHEJ, we found that this effect masked the attenuation of NHEJ by HBZ. Overall, these data suggest that DSB repair mechanisms are impaired not only by Tax but also by HBZ and show that HBZ expression may significantly contribute to the accumulation of chromosomal abnormalities during HTLV-1-mediated oncogenesis.IMPORTANCE Human T-cell leukemia virus type 1 (HTLV-1) infects 15 million to 20 million people worldwide. Approximately 90% of infected individuals are asymptomatic and may remain undiagnosed, increasing the risk that they will unknowingly transmit the virus. About 5% of the HTLV-1-positive population develop adult T-cell leukemia (ATL), a fatal disease that is not highly responsive to treatment. Although ATL development remains poorly understood, two viral proteins, Tax and HBZ, have been implicated in driving disease progression by manipulating host cell signaling and transcriptional pathways. Unlike Tax, HBZ expression is consistently observed in all infected individuals, making it important to elucidate the specific role of HBZ in disease progression. Here, we present evidence that HBZ could promote the accumulation of double-stranded DNA breaks (DSBs) through the attenuation of the nonhomologous end joining (NHEJ) repair pathway. This effect may lead to genome instability, ultimately contributing to the development of ATL.
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14
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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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Piskacek M, Havelka M, Rezacova M, Knight A. The 9aaTAD Transactivation Domains: From Gal4 to p53. PLoS One 2016; 11:e0162842. [PMID: 27618436 PMCID: PMC5019370 DOI: 10.1371/journal.pone.0162842] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 08/29/2016] [Indexed: 12/30/2022] Open
Abstract
The family of the Nine amino acid Transactivation Domain, 9aaTAD family, comprises currently over 40 members. The 9aaTAD domains are universally recognized by the transcriptional machinery from yeast to man. We had identified the 9aaTAD domains in the p53, Msn2, Pdr1 and B42 activators by our prediction algorithm. In this study, their competence to activate transcription as small peptides was proven. Not surprisingly, we elicited immense 9aaTAD divergence in hundreds of identified orthologs and numerous examples of the 9aaTAD species' convergence. We found unforeseen similarity of the mammalian p53 with yeast Gal4 9aaTAD domains. Furthermore, we identified artificial 9aaTAD domains generated accidentally by others. From an evolutionary perspective, the observed easiness to generate 9aaTAD transactivation domains indicates the natural advantage for spontaneous generation of transcription factors from DNA binding precursors.
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Affiliation(s)
- Martin Piskacek
- Laboratory of Cancer Biology and Genetics, Department of Pathological Physiology, Faculty of Medicine, Masaryk University Brno, Kamenice 5, 625 00, Brno, Czech Republic
| | - Marek Havelka
- Laboratory of Cancer Biology and Genetics, Department of Pathological Physiology, Faculty of Medicine, Masaryk University Brno, Kamenice 5, 625 00, Brno, Czech Republic
| | - Martina Rezacova
- Laboratory of Cancer Biology and Genetics, Department of Pathological Physiology, Faculty of Medicine, Masaryk University Brno, Kamenice 5, 625 00, Brno, Czech Republic
| | - Andrea Knight
- Gamma Delta T Cell Laboratory, Department of Pathological Physiology, Faculty of Medicine, Masaryk University Brno, Kamenice 5, 625 00, Brno, Czech Republic
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16
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Murphy J, Hall WW, Ratner L, Sheehy N. Novel interactions between the HTLV antisense proteins HBZ and APH-2 and the NFAR protein family: Implications for the HTLV lifecycles. Virology 2016; 494:129-42. [PMID: 27110706 DOI: 10.1016/j.virol.2016.04.012] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Revised: 04/07/2016] [Accepted: 04/08/2016] [Indexed: 01/17/2023]
Abstract
The human T-cell leukaemia virus type 1 and type 2 (HTLV-1/HTLV-2) antisense proteins HBZ and APH-2 play key roles in the HTLV lifecycles and persistence in the host. Nuclear Factors Associated with double-stranded RNA (NFAR) proteins NF90/110 function in the lifecycles of several viruses and participate in host innate immunity against infection and oncogenesis. Using GST pulldown and co-immunoprecipitation assays we demonstrate specific novel interactions between HBZ/APH-2 and NF90/110 and characterised the protein domains involved. Moreover we show that NF90/110 significantly enhance Tax mediated LTR activation, an effect that was abolished by HBZ but enhanced by APH-2. Additionally we found that HBZ and APH-2 modulate the promoter activity of survivin and are capable of antagonising NF110-mediated survivin activation. Thus interactions between HTLV antisense proteins and the NFAR protein family have an overall positive impact on HTLV infection. Hence NFARs may represent potential therapeutic targets in HTLV infected cells.
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Affiliation(s)
- Jane Murphy
- Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - William W Hall
- Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Lee Ratner
- Department of Medicine, Division of Molecular Oncology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Noreen Sheehy
- Centre for Research in Infectious Diseases, School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland
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17
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Dyson HJ, Wright PE. Role of Intrinsic Protein Disorder in the Function and Interactions of the Transcriptional Coactivators CREB-binding Protein (CBP) and p300. J Biol Chem 2016; 291:6714-22. [PMID: 26851278 DOI: 10.1074/jbc.r115.692020] [Citation(s) in RCA: 216] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The transcriptional coactivators CREB-binding protein (CBP) and p300 undergo a particularly rich set of interactions with disordered and partly ordered partners, as a part of their ubiquitous role in facilitating transcription of genes. CBP and p300 contain a number of small structured domains that provide scaffolds for the interaction of disordered transactivation domains from a wide variety of partners, including p53, hypoxia-inducible factor 1α (HIF-1α), NF-κB, and STAT proteins, and are the targets for the interactions of disordered viral proteins that compete with cellular factors to disrupt signaling and subvert the cell cycle. The functional diversity of the CBP/p300 interactome provides an excellent example of the power of intrinsic disorder to facilitate the complexity of living systems.
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Affiliation(s)
- H Jane Dyson
- From the Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037-1000
| | - Peter E Wright
- From the Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California 92037-1000
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18
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Zhao T. The Role of HBZ in HTLV-1-Induced Oncogenesis. Viruses 2016; 8:v8020034. [PMID: 26848677 PMCID: PMC4776189 DOI: 10.3390/v8020034] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 01/25/2016] [Accepted: 01/28/2016] [Indexed: 02/06/2023] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL) and chronic inflammatory diseases. HTLV-1 bZIP factor (HBZ) is transcribed as an antisense transcript of the HTLV-1 provirus. Among the HTLV-1-encoded viral genes, HBZ is the only gene that is constitutively expressed in all ATL cases. Recent studies have demonstrated that HBZ plays an essential role in oncogenesis by regulating viral transcription and modulating multiple host factors, as well as cellular signaling pathways, that contribute to the development and continued growth of cancer. In this article, I summarize the current knowledge of the oncogenic function of HBZ in cell proliferation, apoptosis, T-cell differentiation, immune escape, and HTLV-1 pathogenesis.
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Affiliation(s)
- Tiejun Zhao
- College of Chemistry and Life Sciences, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China.
- Key Lab of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Normal University, 688 Yingbin Road, Jinhua 321004, China.
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19
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Ithuralde RE, Turjanski AG. Phosphorylation Regulates the Bound Structure of an Intrinsically Disordered Protein: The p53-TAZ2 Case. PLoS One 2016; 11:e0144284. [PMID: 26742101 PMCID: PMC4712144 DOI: 10.1371/journal.pone.0144284] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 11/15/2015] [Indexed: 12/20/2022] Open
Abstract
Disordered regions and Intrinsically Disordered Proteins (IDPs) are involved in critical cellular processes and may acquire a stable three-dimensional structure only upon binding to their partners. IDPs may follow a folding-after-binding process, known as induced folding, or a folding-before-binding process, known as conformational selection. The transcription factor p53 is involved in the regulation of cellular events that arise upon stress or DNA damage. The p53 domain structure is composed of an N-terminal transactivation domain (p53TAD), a DNA Binding Domain and a tetramerization domain. The activity of TAD is tightly regulated by interactions with cofactors, inhibitors and phosphorylation. To initiate transcription, p53TAD binds to the TAZ2 domain of CBP, a co-transcription factor, and undergoes a folding and binding process, as revealed by the recent NMR structure of the complex. The activity of p53 is regulated by phosphorylation at multiple sites on the TAD domain and recent studies have shown that modifications at three residues affect the binding towards TAZ2. However, we still do not know how these phosphorylations affect the structure of the bound state and, therefore, how they regulate the p53 function. In this work, we have used computational simulations to understand how phosphorylation affects the structure of the p53TAD:TAZ2 complex and regulates the recognition mechanism. Phosphorylation has been proposed to enhance binding by direct interaction with the folded protein or by changing the unbound conformation of IDPs, for example by pre-folding the protein favoring the recognition mechanism. Here, we show an interesting turn in the p53 case: phosphorylation mainly affects the bound structure of p53TAD, highlighting the complexity of IDP protein-protein interactions. Our results are in agreement with previous experimental studies, allowing a clear picture of how p53 is regulated by phosphorylation and giving new insights into how post-translational modifications can regulate the function of IDPs.
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Affiliation(s)
- Raúl Esteban Ithuralde
- Departamento de Química Inorgánica, Analítica y Química Física y Departamento de Química Biológica-Facultad de Ciencias Exacas y Naturales-Universidad de Buenos Aires, ciudad de Buenos Aires, Argentina
- INQUIMAE-Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires/Consejo Nacional de Investigaciones Científicas y Técnicas-CONICET, ciudad de Buenos Aires, Argentina
| | - Adrián Gustavo Turjanski
- Departamento de Química Inorgánica, Analítica y Química Física y Departamento de Química Biológica-Facultad de Ciencias Exacas y Naturales-Universidad de Buenos Aires, ciudad de Buenos Aires, Argentina
- INQUIMAE-Facultad de Ciencias Exactas y Naturales-Universidad de Buenos Aires/Consejo Nacional de Investigaciones Científicas y Técnicas-CONICET, ciudad de Buenos Aires, Argentina
- * E-mail:
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20
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Nagulapalli M, Maji S, Dwivedi N, Dahiya P, Thakur JK. Evolution of disorder in Mediator complex and its functional relevance. Nucleic Acids Res 2015; 44:1591-612. [PMID: 26590257 PMCID: PMC4770211 DOI: 10.1093/nar/gkv1135] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Accepted: 10/18/2015] [Indexed: 12/27/2022] Open
Abstract
Mediator, an important component of eukaryotic transcriptional machinery, is a huge multisubunit complex. Though the complex is known to be conserved across all the eukaryotic kingdoms, the evolutionary topology of its subunits has never been studied. In this study, we profiled disorder in the Mediator subunits of 146 eukaryotes belonging to three kingdoms viz., metazoans, plants and fungi, and attempted to find correlation between the evolution of Mediator complex and its disorder. Our analysis suggests that disorder in Mediator complex have played a crucial role in the evolutionary diversification of complexity of eukaryotic organisms. Conserved intrinsic disordered regions (IDRs) were identified in only six subunits in the three kingdoms whereas unique patterns of IDRs were identified in other Mediator subunits. Acquisition of novel molecular recognition features (MoRFs) through evolution of new subunits or through elongation of the existing subunits was evident in metazoans and plants. A new concept of ‘junction-MoRF’ has been introduced. Evolutionary link between CBP and Med15 has been provided which explain the evolution of extended-IDR in CBP from Med15 KIX-IDR junction-MoRF suggesting role of junction-MoRF in evolution and modulation of protein–protein interaction repertoire. This study can be informative and helpful in understanding the conserved and flexible nature of Mediator complex across eukaryotic kingdoms.
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Affiliation(s)
- Malini Nagulapalli
- Plant Mediator Lab, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Sourobh Maji
- Plant Mediator Lab, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Nidhi Dwivedi
- Plant Mediator Lab, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Pradeep Dahiya
- Plant Mediator Lab, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
| | - Jitendra K Thakur
- Plant Mediator Lab, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi 110067, India
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21
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Abstract
Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that causes cancer (Adult T cell Leukemia, ATL) and a spectrum of inflammatory diseases (mainly HTLV-associated myelopathy—tropical spastic paraparesis, HAM/TSP). Since virions are particularly unstable, HTLV-1 transmission primarily occurs by transfer of a cell carrying an integrated provirus. After transcription, the viral genomic RNA undergoes reverse transcription and integration into the chromosomal DNA of a cell from the newly infected host. The virus then replicates by either one of two modes: (i) an infectious cycle by virus budding and infection of new targets and (ii) mitotic division of cells harboring an integrated provirus. HTLV-1 replication initiates a series of mechanisms in the host including antiviral immunity and checkpoint control of cell proliferation. HTLV-1 has elaborated strategies to counteract these defense mechanisms allowing continuous persistence in humans.
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Piskacek M, Vasku A, Hajek R, Knight A. Shared structural features of the 9aaTAD family in complex with CBP. MOLECULAR BIOSYSTEMS 2015; 11:844-51. [DOI: 10.1039/c4mb00672k] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Analysis of E2A, MLL, FOXO3 and p53 structural data defines fundamental requirements and sheds light on the ambiguous 9aaTAD domain.
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Affiliation(s)
- Martin Piskacek
- Department of Pathological Physiology
- Faculty of Medicine
- Masaryk University Brno
- Czech Republic
| | - Anna Vasku
- Department of Pathological Physiology
- Faculty of Medicine
- Masaryk University Brno
- Czech Republic
| | | | - Andrea Knight
- Department of Pathological Physiology
- Faculty of Medicine
- Masaryk University Brno
- Czech Republic
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23
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HBZ stimulates brain-derived neurotrophic factor/TrkB autocrine/paracrine signaling to promote survival of human T-cell leukemia virus type 1-Infected T cells. J Virol 2014; 88:13482-94. [PMID: 25210182 DOI: 10.1128/jvi.02285-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
UNLABELLED Brain-derived neurotrophic factor (BDNF) is a neurotrophin that promotes neuronal proliferation, survival, and plasticity. These effects occur through autocrine and paracrine signaling events initiated by interactions between secreted BDNF and its high-affinity receptor, TrkB. A BDNF/TrkB autocrine/paracrine signaling loop has additionally been implicated in augmenting the survival of cells representing several human cancers and is associated with poor patient prognosis. Adult T-cell leukemia (ATL) is a fatal malignancy caused by infection with the complex retrovirus human T-cell leukemia virus type 1 (HTLV-1). In this study, we found that the HTLV-1-encoded protein HBZ activates expression of BDNF, and consistent with this effect, BDNF expression is elevated in HTLV-1-infected T-cell lines compared to uninfected T cells. Expression of TrkB is also higher in HTLV-1-infected T-cell lines than in uninfected T cells. Furthermore, levels of both BDNF and TrkB mRNAs are elevated in peripheral blood mononuclear cells (PBMCs) from ATL patients, and ATL patient sera contain higher concentrations of BDNF than sera from noninfected individuals. Finally, chemical inhibition of TrkB signaling increases apoptosis in HTLV-1-infected T cells and reduces phosphorylation of glycogen synthase kinase 3β (GSK-3β), a downstream target in the signaling pathway. These results suggest that HBZ contributes to an active BDNF/TrkB autocrine/paracrine signaling loop in HTLV-1-infected T cells that enhances the survival of these cells. IMPORTANCE Infection with human T-cell leukemia virus type 1 (HTLV-1) can cause a rare form of leukemia designated adult T-cell leukemia (ATL). Because ATL patients are unresponsive to chemotherapy, this malignancy is fatal. As a retrovirus, HTLV-1 integrates its genome into a host cell chromosome in order to utilize host factors for replication and expression of viral proteins. However, in infected cells from ATL patients, the viral genome is frequently modified to block expression of all but a single viral protein. This protein, known as HBZ, is therefore believed to modulate cellular pathways necessary for the leukemic state and the chemotherapeutic resistance of the cell. Here we provide evidence to support this hypothesis. We found that HBZ promotes a BDNF/TrkB autocrine/paracrine signaling pathway that is known to enhance the survival and chemotherapeutic resistance of other types of cancer cells. It is possible that inhibition of this pathway may improve treatments for ATL.
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Allostery within a transcription coactivator is predominantly mediated through dissociation rate constants. Proc Natl Acad Sci U S A 2014; 111:12055-60. [PMID: 25092343 DOI: 10.1073/pnas.1405815111] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The kinase-inducible domain interacting (KIX) domain of CREB binding protein binds to multiple intrinsically disordered transcription factors in vivo at two distinct sites on its surface. Several reports have been made of allosteric communication between these two sites in this well-characterized model system. In this work, we have performed fluorescence stopped-flow measurements to investigate the kinetics of binding of five KIX binding proteins. We find that they all have similar association and dissociation rate constants for complex formation, despite their wide range of intrinsic helical propensities. Furthermore, by careful arrangement of pseudofirst-order conditions, we have been able to show that both association and dissociation rate constants are decreased when a partner is bound at the alternative site. These decreases suggest that positive allosteric effects are not mediated by structural changes in binding sites but rather, through a more general mechanism, largely mediated through dissociation, which we propose is largely related to changes in the flexibility of the KIX domain itself.
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25
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Dissecting allosteric effects of activator-coactivator complexes using a covalent small molecule ligand. Proc Natl Acad Sci U S A 2014; 111:12061-6. [PMID: 25049401 DOI: 10.1073/pnas.1406033111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Allosteric binding events play a critical role in the formation and stability of transcriptional activator-coactivator complexes, perhaps in part due to the often intrinsically disordered nature of one or more of the constituent partners. The kinase-inducible domain interacting (KIX) domain of the master coactivator CREB binding protein/p300 is a conformationally dynamic domain that complexes with transcriptional activators at two discrete binding sites in allosteric communication. The complexation of KIX with the transcriptional activation domain of mixed-lineage leukemia protein leads to an enhancement of binding by the activation domain of CREB (phosphorylated kinase-inducible domain of CREB) to the second site. A transient kinetic analysis of the ternary complex formation aided by small molecule ligands that induce positive or negative cooperative binding reveals that positive cooperativity is largely governed by stabilization of the bound complex as indicated by a decrease in koff. Thus, this suggests the increased binding affinity for the second ligand is not due to an allosteric creation of a more favorable binding interface by the first ligand. This is consistent with data from us and from others indicating that the on rates of conformationally dynamic proteins approach the limits of diffusion. In contrast, negative cooperativity is manifested by alterations in both kon and koff, suggesting stabilization of the binary complex.
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26
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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: 68] [Impact Index Per Article: 6.2] [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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27
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Wang F, Marshall CB, Ikura M. Transcriptional/epigenetic regulator CBP/p300 in tumorigenesis: structural and functional versatility in target recognition. Cell Mol Life Sci 2013; 70:3989-4008. [PMID: 23307074 PMCID: PMC11113169 DOI: 10.1007/s00018-012-1254-4] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 11/08/2012] [Accepted: 12/20/2012] [Indexed: 01/19/2023]
Abstract
In eukaryotic cells, gene transcription is regulated by sequence-specific DNA-binding transcription factors that recognize promoter and enhancer elements near the transcriptional start site. Some coactivators promote transcription by connecting transcription factors to the basal transcriptional machinery. The highly conserved coactivators CREB-binding protein (CBP) and its paralog, E1A-binding protein (p300), each have four separate transactivation domains (TADs) that interact with the TADs of a number of DNA-binding transcription activators as well as general transcription factors (GTFs), thus mediating recruitment of basal transcription machinery to the promoter. Most promoters comprise multiple activator-binding sites, and many activators contain tandem TADs, thus multivalent interactions may stabilize CBP/p300 at the promoter, and intrinsically disordered regions in CBP/p300 and many activators may confer adaptability to these multivalent complexes. CBP/p300 contains a catalytic histone acetyltransferase (HAT) domain, which remodels chromatin to 'relax' its superstructure and enables transcription of proximal genes. The HAT activity of CBP/p300 also acetylates some transcription factors (e.g., p53), hence modulating the function of key transcriptional regulators. Through these numerous interactions, CBP/p300 has been implicated in complex physiological and pathological processes, and, in response to different signals, can drive cells towards proliferation or apoptosis. Dysregulation of the transcriptional and epigenetic functions of CBP/p300 is associated with leukemia and other types of cancer, thus it has been recognized as a potential anti-cancer drug target. In this review, we focus on recent exciting findings in the structural mechanisms of CBP/p300 involving multivalent and dynamic interactions with binding partners, which may pave new avenues for anti-cancer drug development.
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Affiliation(s)
- Feng Wang
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
- Present Address: Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, TN 37232 USA
| | - Christopher B. Marshall
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
| | - Mitsuhiko Ikura
- Department of Medical Biophysics, University of Toronto, Toronto, ON M5G 2M9 Canada
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Cancer Center, University Health Network, Toronto, ON M5G 1L7 Canada
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28
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Barbeau B, Peloponese JM, Mesnard JM. Functional comparison of antisense proteins of HTLV-1 and HTLV-2 in viral pathogenesis. Front Microbiol 2013; 4:226. [PMID: 23966985 PMCID: PMC3736048 DOI: 10.3389/fmicb.2013.00226] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/25/2013] [Indexed: 12/24/2022] Open
Abstract
The production of antisense transcripts from the 3′ long terminal repeat (LTR) in human T-lymphotropic retroviruses has now been clearly demonstrated. After the identification of the antisense strand-encoded human T-lymphotropic virus type 1 (HTLV-1) bZIP (HBZ) factor, we reported that HBZ could interact with CRE-binding protein (CREB) transcription factors and consequently turn off the important activating potential of the viral Tax protein on HTLV-1 5′ LTR promoter activity. We have recently accumulated new results demonstrating that antisense transcripts also exist in HTLV-2, -3, and -4. Furthermore, our data have confirmed the existence of encoded proteins from these antisense transcripts (termed antisense proteins of HTLVs or APHs). APHs are also involved in the down-regulation of Tax-dependent viral transcription. In this review, we will focus on the different molecular mechanisms used by HBZ and APH-2 to control viral expression. While HBZ interacts with CREB through its basic zipper domain, APH-2 binds to this cellular factor through a five amino acid motif localized in its carboxyl terminus. Moreover, unlike APH-2, HBZ possesses an N-terminal activation domain that also contributes to the inhibition of the viral transcription by interacting with the KIX domain of p300/CBP. On the other hand, HBZ was found to induce T cell proliferation while APH-2 was unable to promote such proliferation. Interestingly, HTLV-2 has not been causally linked to human T cell leukemia, while HTLV-1 is responsible for the development of the adult T cell leukemia/lymphoma. We will further discuss the possible role played by antisense proteins in the establishment of pathologies induced by viral infection.
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Affiliation(s)
- Benoit Barbeau
- Département des sciences biologiques and Centre de recherche BioMed, Université du Québec à Montréal Montréal, QC, Canada
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29
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Borowiak M, Kuhlmann AS, Girard S, Gazzolo L, Mesnard JM, Jalinot P, Dodon MD. HTLV-1 bZIP factor impedes the menin tumor suppressor and upregulates JunD-mediated transcription of the hTERT gene. Carcinogenesis 2013; 34:2664-72. [PMID: 23784080 DOI: 10.1093/carcin/bgt221] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Telomerase activity in cancer cells is dependent on the transcriptional regulation of the human telomerase reverse transcriptase (hTERT) gene, encoding the catalytic subunit of human telomerase. We have shown previously that HTLV-1 basic leucine zipper (HBZ), a viral regulatory protein encoded by the human retrovirus, human T-cell leukemia virus, type 1 (HTLV-1) cooperates with JunD to enhance hTERT transcription in adult T-cell leukemia (ATL) cells. Menin, the product of the tumor-suppressor MEN-1 gene, also interacts with JunD, represses its transcriptional activity and downregulates telomerase expression. The main objective of this study was to examine how menin and HBZ get involved in the regulation of hTERT transcription. In this study, we report that JunD and menin form a repressor complex of hTERT transcription in HBZ-negative cells. Conversely, in HBZ-positive cells, the formation of a JunD/HBZ/menin ternary complex and the recruitment of p300 histone acetyl transferase activity by HBZ lead to a decreased activity of the JunD-menin suppressor unit that correlates with the activation of hTERT transcription. Silencing HBZ or menin expression in ATL cells confirms that these proteins are differentially involved in telomerase regulation. These results propose that HBZ, by impeding the tumor-suppressor activity of menin, functions as a leukemogenic cofactor to upregulate gene transcription and promote JunD-mediated leukemogenesis.
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Affiliation(s)
- Malgorzata Borowiak
- Laboratoire de Biologie Moléculaire de la Cellule, Unité Mixte de Recherche 5239, Centre National de la Recherche Scientifique, Ecole Normale Supérieure, 69364 Lyon Cedex 07, France
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30
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Wang N, Majmudar CY, Pomerantz WC, Gagnon JK, Sadowsky JD, Meagher JL, Johnson TK, Stuckey JA, Brooks CL, Wells JA, Mapp AK. Ordering a dynamic protein via a small-molecule stabilizer. J Am Chem Soc 2013; 135:3363-6. [PMID: 23384013 PMCID: PMC3607081 DOI: 10.1021/ja3122334] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Like many coactivators, the GACKIX domain of the master coactivator CBP/p300 recognizes transcriptional activators of diverse sequence composition via dynamic binding surfaces. The conformational dynamics of GACKIX that underlie its function also render it especially challenging for structural characterization. We have found that the ligand discovery strategy of Tethering is an effective method for identifying small-molecule fragments that stabilize the GACKIX domain, enabling for the first time the crystallographic characterization of this important motif. The 2.0 Å resolution structure of GACKIX complexed to a small molecule was further analyzed by molecular dynamics simulations, which revealed the importance of specific side-chain motions that remodel the activator binding site in order to accommodate binding partners of distinct sequence and size. More broadly, these results suggest that Tethering can be a powerful strategy for identifying small-molecule stabilizers of conformationally malleable proteins, thus facilitating their structural characterization and accelerating the discovery of small-molecule modulators.
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Affiliation(s)
- Ningkun Wang
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109
| | | | | | - Jessica K. Gagnon
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Jack D. Sadowsky
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158
| | | | - Taylor K. Johnson
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - Jeanne A. Stuckey
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109
| | - Charles L. Brooks
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109
| | - James A. Wells
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA 94158
| | - Anna K. Mapp
- Program in Chemical Biology, University of Michigan, Ann Arbor, MI 48109
- Department of Chemistry, University of Michigan, Ann Arbor, MI 48109
- Department of Medicinal Chemistry, University of Michigan, Ann Arbor, MI 48109
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31
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Abstract
E-proteins are critical transcription factors in B-cell lymphopoiesis. E2A, 1 of 3 E-protein-encoding genes, is implicated in the induction of acute lymphoblastic leukemia through its involvement in the chromosomal translocation 1;19 and consequent expression of the E2A-PBX1 oncoprotein. An interaction involving a region within the N-terminal transcriptional activation domain of E2A-PBX1, termed the PCET motif, which has previously been implicated in E-protein silencing, and the KIX domain of the transcriptional coactivator CBP/p300, critical for leukemogenesis. However, the structural details of this interaction remain unknown. Here we report the structure of a 1:1 complex between PCET motif peptide and the KIX domain. Residues throughout the helical PCET motif that contact the KIX domain are important for both binding KIX and bone marrow immortalization by E2A-PBX1. These results provide molecular insights into E-protein-driven differentiation of B-cells and the mechanism of E-protein silencing, and reveal the PCET/KIX interaction as a therapeutic target for E2A-PBX1-induced leukemia.
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Zhao T, Matsuoka M. HBZ and its roles in HTLV-1 oncogenesis. Front Microbiol 2012; 3:247. [PMID: 22787458 PMCID: PMC3391691 DOI: 10.3389/fmicb.2012.00247] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 06/19/2012] [Indexed: 12/16/2022] Open
Abstract
Human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATL). The minus strand of HTLV-1 provirus encodes a bZIP protein donated as HTLV-1 bZIP factor (HBZ). Among the HTLV-1 regulatory and accessory genes, the tax and HBZ genes were thought to play critical roles in oncogenesis. However, HBZ is the only gene that remains intact and is consistently expressed in all ATL cases, while the tax gene is frequently inactivated by epigenetic modifications or deletion of the 5’LTR. HBZ gene promotes the proliferation of ATL cells through its mRNA form. Moreover, HBZ induces T-cell lymphoma and systemic inflammation in vivo. HBZ fulfills its functions mainly through regulating HTLV-1 5’LTR transcription and modulating a variety of cellular signaling pathways which are related with cell growth, immune response, and T-cell differentiation. Taken together, the multiple functions of HBZ render its predominant function in leukemogenesis of ATL.
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Affiliation(s)
- Tiejun Zhao
- Laboratory of Virus Control, Institute for Virus Research, Kyoto University, Kyoto, Japan
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Human T-cell leukemia virus type 1 (HTLV-1) bZIP factor requires cellular transcription factor JunD to upregulate HTLV-1 antisense transcription from the 3' long terminal repeat. J Virol 2012; 86:9070-8. [PMID: 22696638 DOI: 10.1128/jvi.00661-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Infection with the human T-cell leukemia virus type 1 (HTLV-1) results in a variety of diseases including adult T-cell leukemia (ATL), a fatal malignancy characterized by the uncontrolled proliferation of virally infected CD4(+) T cells. The HTLV-1 basic leucine zipper factor (HBZ) is believed to contribute to development and maintenance of ATL. Unlike the other HTLV-1 genes, the hbz gene is encoded on the complementary strand of the provirus and therefore is not under direct control of the promoter within the 5' long terminal repeat (LTR) of the provirus. This promoter can undergo inactivating genetic or epigenetic changes during the course of ATL that eliminates expression of all viral genes except that of hbz. In contrast, repressive modifications are not known to occur on the hbz promoter located in the 3' LTR, and hbz expression has been consistently detected in all ATL patient samples. Although Sp1 regulates basal transcription from the HBZ promoter, other factors that activate transcription remain undefined. In this study, we used a proviral reporter construct deleted of the 5' LTR to show that HBZ upregulates its own expression through cooperation with JunD. Activation of antisense transcription was apparent in serum-deprived cells in which the level of JunD was elevated, and elimination of JunD expression by gene knockout or shRNA-mediated knockdown abrogated this effect. Activation through HBZ and JunD additionally required Sp1 binding at the hbz promoter. These data favor a model in which JunD is recruited to the promoter through Sp1, where it heterodimerizes with HBZ thereby enhancing its activity. Separately, hbz gene expression led to an increase in JunD abundance, and this effect correlated with emergence of features of transformed cells in immortalized fibroblasts. Overall, our results suggest that JunD represents a novel therapeutic target for the treatment of ATL.
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Wurm T, Wright DG, Polakowski N, Mesnard JM, Lemasson I. The HTLV-1-encoded protein HBZ directly inhibits the acetyl transferase activity of p300/CBP. Nucleic Acids Res 2012; 40:5910-25. [PMID: 22434882 PMCID: PMC3401433 DOI: 10.1093/nar/gks244] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The homologous cellular coactivators p300 and CBP contain intrinsic lysine acetyl transferase (termed HAT) activity. This activity is responsible for acetylation of several sites on the histones as well as modification of transcription factors. In a previous study, we found that HBZ, encoded by the Human T-cell Leukemia Virus type 1 (HTLV-1), binds to multiple domains of p300/CBP, including the HAT domain. In this study, we found that HBZ inhibits the HAT activity of p300/CBP through the bZIP domain of the viral protein. This effect correlated with a reduction of H3K18 acetylation, a specific target of p300/CBP, in cells expressing HBZ. Interestingly, lower levels of H3K18 acetylation were detected in HTLV-1 infected cells compared to non-infected cells. The inhibitory effect of HBZ was not limited to histones, as HBZ also inhibited acetylation of the NF-κB subunit, p65, and the tumor suppressor, p53. Recent studies reported that mutations in the HAT domain of p300/CBP that cause a defect in acetylation are found in certain types of leukemia. These observations suggest that inhibition of the HAT activity by HBZ is important for the development of adult T-cell leukemia associated with HTLV-1 infection.
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Affiliation(s)
- Torsten Wurm
- East Carolina University, Brody School of Medicine, Greenville, NC 27834, USA
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