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IRF4 as an Oncogenic Master Transcription Factor. Cancers (Basel) 2022; 14:cancers14174314. [PMID: 36077849 PMCID: PMC9454692 DOI: 10.3390/cancers14174314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 08/30/2022] [Accepted: 08/31/2022] [Indexed: 11/25/2022] Open
Abstract
Simple Summary Master transcription factors regulate essential developmental processes and cellular maintenance that characterize cell identity. Many of them also serve as oncogenes when aberrantly expressed or activated. IRF4 is one of prime examples of oncogenic master transcription factors that has been implicated in various mature lymphoid neoplasms. IRF4 forms unique regulatory circuits and induces oncogenic transcription programs through the interactions with upstream pathways and binding partners. Abstract IRF4 is a transcription factor in the interferon regulatory factor (IRF) family. Since the discovery of this gene, various research fields including immunology and oncology have highlighted the unique characteristics and the importance of IRF4 in several biological processes that distinguish it from other IRF family members. In normal lymphocyte development and immunity, IRF4 mediates critical immune responses via interactions with upstream signaling pathways, such as the T-cell receptor and B-cell receptor pathways, as well as their binding partners, which are uniquely expressed in each cell type. On the other hand, IRF4 acts as an oncogene in various mature lymphoid neoplasms when abnormally expressed. IRF4 induces several oncogenes, such as MYC, as well as genes that characterize each cell type by utilizing its ability as a master regulator of immunity. IRF4 and its upstream factor NF-κB form a transcriptional regulatory circuit, including feedback and feedforward loops, to maintain the oncogenic transcriptional program in malignant lymphoid cells. In this review article, we provide an overview of the molecular functions of IRF4 in mature lymphoid neoplasms and highlight its upstream and downstream pathways, as well as the regulatory circuits mediated by IRF4.
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Amanda S, Tan TK, Iida S, Sanda T. Lineage- and Stage-specific Oncogenicity of IRF4. Exp Hematol 2022; 114:9-17. [PMID: 35908629 DOI: 10.1016/j.exphem.2022.07.300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Revised: 07/22/2022] [Accepted: 07/25/2022] [Indexed: 11/04/2022]
Abstract
Dysregulation of transcription factor genes represents a unique molecular etiology of hematological malignancies. A number of transcription factors that play a role in hematopoietic cell development, lymphocyte activation or their maintenance have been identified as oncogenes or tumor suppressors. Many of them exert oncogenic abilities in a context-dependent manner by governing the key transcriptional program unique to each cell type. IRF4, a member of the interferon regulatory factor (IRF) family, acts as an essential regulator of the immune system and is a prime example of a stage-specific oncogene. The expression and oncogenicity of IRF4 are restricted to mature lymphoid neoplasms, while IRF4 potentially serves as a tumor suppressor in other cellular contexts. This is in marked contrast to its immediate downstream target, MYC, which can cause cancers in a variety of tissues. In this review article, we provide an overview of the roles of IRF4 in the development of the normal immune system and lymphoid neoplasms and discuss the potential mechanisms of lineage- and stage-specific oncogenicity of IRF4.
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Affiliation(s)
- Stella Amanda
- Cancer Science Institute of Singapore, National University of Singapore, 117599, Singapore
| | - Tze King Tan
- Cancer Science Institute of Singapore, National University of Singapore, 117599, Singapore
| | - Shinsuke Iida
- Department of Hematology and Oncology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Aichi, 467-8601 Japan
| | - Takaomi Sanda
- Cancer Science Institute of Singapore, National University of Singapore, 117599, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 117599, Singapore..
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Feed-forward regulatory loop driven by IRF4 and NF-κB in adult T-cell leukemia/lymphoma. Blood 2020; 135:934-947. [PMID: 31972002 DOI: 10.1182/blood.2019002639] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 12/27/2019] [Indexed: 12/14/2022] Open
Abstract
Adult T-cell leukemia/lymphoma (ATL) is a highly aggressive hematological malignancy derived from mature CD4+ T-lymphocytes. Here, we demonstrate the transcriptional regulatory network driven by 2 oncogenic transcription factors, IRF4 and NF-κB, in ATL cells. Gene expression profiling of primary ATL samples demonstrated that the IRF4 gene was more highly expressed in ATL cells than in normal T cells. Chromatin immunoprecipitation sequencing analysis revealed that IRF4-bound regions were more frequently found in super-enhancers than in typical enhancers. NF-κB was found to co-occupy IRF4-bound regulatory elements and formed a coherent feed-forward loop to coordinately regulate genes involved in T-cell functions and development. Importantly, IRF4 and NF-κB regulated several cancer genes associated with super-enhancers in ATL cells, including MYC, CCR4, and BIRC3. Genetic inhibition of BIRC3 induced growth inhibition in ATL cells, implicating its role as a critical effector molecule downstream of the IRF4-NF-κB transcriptional network.
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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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Naito T, Yasunaga JI, Mitobe Y, Shirai K, Sejima H, Ushirogawa H, Tanaka Y, Nakamura T, Hanada K, Fujii M, Matsuoka M, Saito M. Distinct gene expression signatures induced by viral transactivators of different HTLV-1 subgroups that confer a different risk of HAM/TSP. Retrovirology 2018; 15:72. [PMID: 30400920 PMCID: PMC6219256 DOI: 10.1186/s12977-018-0454-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Accepted: 10/26/2018] [Indexed: 12/11/2022] Open
Abstract
Background Among human T cell leukemia virus type 1 (HTLV-1)-infected individuals, there is an association between HTLV-1 tax subgroups (subgroup-A or subgroup-B) and the risk of HAM/TSP in the Japanese population. To investigate the role of HTLV-1 subgroups in viral pathogenesis, we studied the functional difference in the subgroup-specific viral transcriptional regulators Tax and HBZ using microarray analysis, reporter gene assays, and evaluation of viral-host protein–protein interaction. Results (1) Transcriptional changes in Jurkat Tet-On human T-cells that express each subgroup of Tax or HBZ protein under the control of an inducible promoter revealed different target gene profiles; (2) the number of differentially regulated genes induced by HBZ was 2–3 times higher than that induced by Tax; (3) Tax and HBZ induced the expression of different classes of non-coding RNAs (ncRNAs); (4) the chemokine CXCL10, which has been proposed as a prognostic biomarker for HAM/TSP, was more efficiently induced by subgroup-A Tax (Tax-A) than subgroup-B Tax (Tax-B), in vitro as well as in unmanipulated (ex vivo) PBMCs obtained from HAM/TSP patients; (5) reporter gene assays indicated that although transient Tax expression in an HTLV-1-negative human T-cell line activated the CXCL10 gene promoter through the NF-κB pathway, there was no difference in the ability of each subgroup of Tax to activate the CXCL10 promoter; however, (6) chromatin immunoprecipitation assays showed that the ternary complex containing Tax-A is more efficiently recruited onto the promoter region of CXCL10, which contains two NF-κB binding sites, than that containing Tax-B. Conclusions Our results indicate that different HTLV-1 subgroups are characterized by different patterns of host gene expression. Differential expression of pathogenesis-related genes by subgroup-specific Tax or HBZ may be associated with the onset of HAM/TSP. Electronic supplementary material The online version of this article (10.1186/s12977-018-0454-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tadasuke Naito
- Department of Microbiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Jun-Ichirou Yasunaga
- Laboratory of Virus Control, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan
| | - Yuichi Mitobe
- Laboratory of Virus Control, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan.,Division of Gene Regulation and Signal Transduction, Research Center for Genomic Medicine, Saitama Medical University, Saitama, Japan
| | - Kazumasa Shirai
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan
| | - Hiroe Sejima
- Department of Microbiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Hiroshi Ushirogawa
- Department of Microbiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan
| | - Yuetsu Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan
| | - Tatsufumi Nakamura
- Department of Social Work, Faculty of Human and Social Studies, Nagasaki International University, 2825-7 Huis Ten Bosch Machi, Sasebo, Nagasaki, 859-3298, Japan
| | - Kousuke Hanada
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, Fukuoka, Japan
| | - Masahiro Fujii
- Division of Virology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Masao Matsuoka
- Laboratory of Virus Control, Institute for Frontier Life and Medical Sciences, Kyoto University, Kyoto, Japan.,Department of Hematology, Rheumatology and Infectious Disease, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Mineki Saito
- Department of Microbiology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan.
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Tanaka Y, Mizuguchi M, Takahashi Y, Fujii H, Tanaka R, Fukushima T, Tomoyose T, Ansari AA, Nakamura M. Human T-cell leukemia virus type-I Tax induces the expression of CD83 on T cells. Retrovirology 2015; 12:56. [PMID: 26129803 PMCID: PMC4487981 DOI: 10.1186/s12977-015-0185-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Accepted: 06/21/2015] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND CD83, a cell surface glycoprotein that is stably expressed on mature dendritic cells, can be transiently induced on other hematopoietic cell lineages upon cell activation. In contrast to the membrane form of CD83, soluble CD83 appears to be immunosuppressive. In an analysis of the phenotype of leukemic CD4(+) T cells from patients with adult T-cell leukemia (ATL), we found that a number of primary CD4(+) T cells became positive for cell surface CD83 after short-term culture, and that most of these CD83(+) CD4(+) T cells were positive for human T-cell leukemia virus type-I (HTLV-I) Tax (Tax1). We hypothesized that Tax1 is involved in the induction of CD83. RESULT We found that CD83 was expressed selectively on Tax1-expressing human CD4(+) T cells in short-term cultured peripheral blood mononuclear cells (PBMCs) isolated from HTLV-I(+) donors, including ATL patients and HTLV-I carriers. HTLV-I-infected T cell lines expressing Tax1 also expressed cell surface CD83 and released soluble CD83. CD83 can be expressed in the JPX-9 cell line by cadmium-mediated Tax1 induction and in Jurkat cells or PBMCs by Tax1 introduction via infection with a recombinant adenovirus carrying the Tax1 gene. The CD83 promoter was activated by Tax1 in an NF-κB-dependent manner. Based on a previous report showing soluble CD83-mediated prostaglandin E2 (PGE2) production from human monocytes in vitro, we tested if PGE2 affected HTLV-I propagation, and found that PGE2 strongly stimulated expression of Tax1 and viral structural molecules. CONCLUSIONS Our results suggest that HTLV-I induces CD83 expression on T cells via Tax1 -mediated NF-κB activation, which may promote HTLV-I infection in vivo.
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Affiliation(s)
- Yuetsu Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan.
| | - Mariko Mizuguchi
- Human Gene Sciences Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan.
| | - Yoshiaki Takahashi
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan.
| | - Hideki Fujii
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan.
| | - Reiko Tanaka
- Department of Immunology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara-cho, Okinawa, 903-0215, Japan.
| | - Takuya Fukushima
- Laboratory of Hematoimmunology, School of Health Sciences, Faculty of Medicine, University of the Ryukyus, Okinawa, Japan.
| | - Takeaki Tomoyose
- Division of Endocrinology, Diabetes and Metabolism, Haematology, Rheumatology (Second Department of Internal Medicine), Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.
| | - Aftab A Ansari
- Department of Pathology, Emory University School of Medicine, Atlanta, GA, USA.
| | - Masataka Nakamura
- Human Gene Sciences Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan.
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Romanelli MG, Diani E, Bergamo E, Casoli C, Ciminale V, Bex F, Bertazzoni U. Highlights on distinctive structural and functional properties of HTLV Tax proteins. Front Microbiol 2013; 4:271. [PMID: 24058363 PMCID: PMC3766827 DOI: 10.3389/fmicb.2013.00271] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/20/2013] [Indexed: 12/15/2022] Open
Abstract
Human T cell leukemia viruses (HTLVs) are complex human retroviruses of the Deltaretrovirus genus. Four types have been identified thus far, with HTLV-1 and HTLV-2 much more prevalent than HTLV-3 or HTLV-4. HTLV-1 and HTLV-2 possess strictly related genomic structures, but differ significantly in pathogenicity, as HTLV-1 is the causative agent of adult T cell leukemia and of HTLV-associated myelopathy/tropical spastic paraparesis, whereas HTLV-2 is not associated with neoplasia. HTLVs code for a protein named Tax that is responsible for enhancing viral expression and drives cell transformation. Much effort has been invested to dissect the impact of Tax on signal transduction pathways and to identify functional differences between the HTLV Tax proteins that may explain the distinct oncogenic potential of HTLV-1 and HTLV-2. This review summarizes our current knowledge of Tax-1 and Tax-2 with emphasis on their structure, role in activation of the NF-κB (nuclear factor kappa-B) pathway, and interactions with host factors.
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Shirinian M, Kfoury Y, Dassouki Z, El-Hajj H, Bazarbachi A. Tax-1 and Tax-2 similarities and differences: focus on post-translational modifications and NF-κB activation. Front Microbiol 2013; 4:231. [PMID: 23966989 PMCID: PMC3744011 DOI: 10.3389/fmicb.2013.00231] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 07/29/2013] [Indexed: 11/13/2022] Open
Abstract
Although human T cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2) share similar genetic organization, they have major differences in their pathogenesis and disease manifestation. HTLV-1 is capable of transforming T lymphocytes in infected patients resulting in adult T cell leukemia/lymphoma whereas HTLV-2 is not clearly associated with lymphoproliferative diseases. Numerous studies have provided accumulating evidence on the involvement of the viral transactivators Tax-1 versus Tax-2 in T cell transformation. Tax-1 is a potent transcriptional activator of both viral and cellular genes. Tax-1 post-translational modifications and specifically ubiquitylation and SUMOylation have been implicated in nuclear factor-kappaB (NF-κB) activation and may contribute to its transformation capacity. Although Tax-2 has similar protein structure compared to Tax-1, the two proteins display differences both in their protein–protein interaction and activation of signal transduction pathways. Recent studies on Tax-2 have suggested ubiquitylation and SUMOylation independent mechanisms of NF-κB activation. In this present review, structural and functional differences between Tax-1 and Tax-2 will be summarized. Specifically, we will address their subcellular localization, nuclear trafficking and their effect on cellular regulatory proteins. A special attention will be given to Tax-1/Tax-2 post-translational modification such as ubiquitylation, SUMOylation, phosphorylation, acetylation, NF-κB activation, and protein–protein interactions involved in oncogenecity both in vivo and in vitro.
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Affiliation(s)
- Margret Shirinian
- Department of Internal Medicine, Faculty of Medicine, American University of Beirut Beirut, Lebanon
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The multifaceted oncoprotein Tax: subcellular localization, posttranslational modifications, and NF-κB activation. Adv Cancer Res 2012; 113:85-120. [PMID: 22429853 DOI: 10.1016/b978-0-12-394280-7.00003-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The human T-cell lymphotropic virus type-I (HTLV-I) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL) and of tropical spastic paraparesis/HTLV-I-associated myelopathy. Constitutive NF-κB activation by the viral oncoprotein Tax plays a crucial role in the induction and maintenance of cellular proliferation, transformation, and inhibition of apoptosis. In an attempt to provide a general view of the molecular mechanisms of constitutive Tax-induced NF-κB activation, we summarize in this review the recent body of literature that supports a major role for Tax posttranslational modifications, chiefly ubiquitination, and SUMOylation, in the NF-κB activity of Tax. These modifications indeed participate in the control of Tax subcellular localization and modulate its protein-protein interaction potential. Tax posttranslational modifications, which highlight the ability of HTLV-I to optimize its limited viral genome size, might represent an attractive target for the design of new therapies for ATL.
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Bertazzoni U, Turci M, Avesani F, Di Gennaro G, Bidoia C, Romanelli MG. Intracellular localization and cellular factors interaction of HTLV-1 and HTLV-2 Tax proteins: similarities and functional differences. Viruses 2011; 3:541-560. [PMID: 21994745 PMCID: PMC3185761 DOI: 10.3390/v3050541] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 04/26/2011] [Indexed: 12/24/2022] Open
Abstract
Human T-lymphotropic viruses type 1 (HTLV-1) and type 2 (HTLV-2) present very similar genomic structures but HTLV-1 is more pathogenic than HTLV-2. Is this difference due to their transactivating Tax proteins, Tax-1 and Tax-2, which are responsible for viral and cellular gene activation? Do Tax-1 and Tax-2 differ in their cellular localization and in their interaction pattern with cellular factors? In this review, we summarize Tax-1 and Tax-2 structural and phenotypic properties, their interaction with factors involved in signal transduction and their localization-related behavior within the cell. Special attention will be given to the distinctions between Tax-1 and Tax-2 that likely play an important role in their transactivation activity.
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Affiliation(s)
- Umberto Bertazzoni
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
- Authors to whom correspondence should be addressed; E-Mails: (U.B.); (M.G.R); Tel.: +39-0458027182; Fax: +390458027180
| | - Marco Turci
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Francesca Avesani
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Gianfranco Di Gennaro
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
| | - Carlo Bidoia
- Centre for Research in Infectious Diseases, University College Dublin, Belfield, Dublin 4, Ireland; E-Mail: (C.B.)
| | - Maria Grazia Romanelli
- Department of Life and Reproduction Sciences, University of Verona, Strada le Grazie 8, 37134, Verona, Italy; E-Mails: (M.T.); (F.A.); (G.D.G.)
- Authors to whom correspondence should be addressed; E-Mails: (U.B.); (M.G.R); Tel.: +39-0458027182; Fax: +390458027180
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Ahmed N, Hayashi T, Hasegawa A, Furukawa H, Okamura N, Chida T, Masuda T, Kannagi M. Suppression of human immunodeficiency virus type 1 replication in macrophages by commensal bacteria preferentially stimulating Toll-like receptor 4. J Gen Virol 2010; 91:2804-13. [PMID: 20719993 DOI: 10.1099/vir.0.022442-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Protection from primary human immunodeficiency virus type 1 (HIV-1) infection has not yet been accomplished by vaccines inducing HIV-1-specific acquired immunity. Nevertheless, it has been reported that a small subgroup of women remain resistant to HIV-1 infection under natural conditions. If similar conditions can be induced in uninfected individuals, it will contribute the first line of protection against HIV-1 infection, and also improve the effects of anti-HIV-1 vaccines. We reasoned that innate immunity may be involved in the resistance to HIV-1 infection, and investigated the effects of various Toll-like receptor (TLR) ligands and commensal bacteria on HIV-1 replication in macrophages, one of the initial targets of HIV-1 infection and also the main mediators of innate immunity. We established the HIV-1 reporter monocytic cell line, THP-1/NL4-3luc, which could be differentiated into macrophage-like cells in vitro. In these cells, stimulation of TLR3 and TLR4 by their ligands suppressed HIV-1 expression partly through type I interferon (IFN). Among the commensal bacteria tested, Escherichia coli, Veillonella parvula and Neisseria mucosa suppressed HIV-1 expression, whereas Lactobacillus acidophilus, Prevotella melaninogenica, P. bivia and Mycobacterium smegmatis enhanced it. The bacteria with suppressive effects preferentially stimulated TLR4, whereas the ones with enhancing effects stimulated TLR2. Neutralizing antibodies against TLR4 and IFN-α/β receptor abrogated bacterially mediated HIV-1 suppression. Suppressive effects of E. coli, V. parvula and N. mucosa on HIV-1 replication were reproducible in primary monocyte-derived macrophages following acute HIV-1 infection. These findings suggest that certain commensal bacteria preferentially stimulating TLR4 potentially produce local environments resistant to HIV-1 infection.
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Affiliation(s)
- Nursarat Ahmed
- Department of Immunotherapeutics, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
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Ruimi N, Petrova RD, Agbaria R, Sussan S, Wasser SP, Reznick AZ, Mahajna J. Inhibition of TNFα-induced iNOS expression in HSV-tk transduced 9L glioblastoma cell lines by Marasmius oreades substances through NF-κB- and MAPK-dependent mechanisms. Mol Biol Rep 2010; 37:3801-12. [PMID: 20224909 DOI: 10.1007/s11033-010-0035-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Accepted: 02/24/2010] [Indexed: 01/01/2023]
Abstract
Nitric oxide (NO) is a gaseous, radical molecule that plays a role in various physiological processes. Previously, we reported that transduction of murine colon cancer cells (MC38) with herpes simplex virus thymidine kinase (HSV-tk) gene resulted in a significant over-expression of cyclooxygenase-2 (COX-2) and activation of NF-kB pathway. In this study we show that TNFα, but not LPS, was significantly able to stimulate the production of NO in HSV-tk transduced 9L glioblastoma cell lines, mediated by the up-regulation of iNOS transcript and iNOS protein. The TNFα-induced up-regulation of iNOS expression was mediated by MAPK and NF-κB signaling pathways as revealed by using selective pharmaceutical inhibitors. A culture liquid extract of the edible and medicinal mushroom Marasmius oreades that was previously shown to inhibit iNOS expression in MCF-7 was utilized to prepare fractions and evaluate their ability to affect TNFα-induced iNOS expression in HSV tk transduced 9L cell lines. While most of the tested fractions were shown to inhibit TNFα-induced iNOS expression, they targeted different signaling pathways in a selective fashion. Here, we report that fraction SiSiF1 interfered with IKBα phosphorylation and consequently interfered with NF-κB activation pathway. SiSiF1 showed minimal interference with the phosphorylation of p38 and JNK proteins. In contrast, fraction SiSiF3 selectively inhibited the phosphorylation of p38 and fractions SiSiF4 and SiSiF5 selectively inhibited the phosphorylation of JNK with no observed effect against IKBα and p38 phosphorylation. Our data illustrate the complexity of iNOS regulation in HSV tk transduced 9L cell lines and also the richness of natural products with bioactive substances that may act synergistically through different signaling pathways to affect iNOS gene expression.
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Affiliation(s)
- Nili Ruimi
- Migal-Galilee Technology Center, Cancer Drug Discovery Program, P.O. Box 831, Kiryat Shmona, Israel
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Yoshida M. Molecular approach to human leukemia: isolation and characterization of the first human retrovirus HTLV-1 and its impact on tumorigenesis in adult T-cell leukemia. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2010; 86:117-130. [PMID: 20154469 PMCID: PMC3417562 DOI: 10.2183/pjab.86.117] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 12/25/2009] [Indexed: 05/28/2023]
Abstract
Molecular biology of mouse and chicken retroviruses had identified oncogenes and provided a revolutionary concept in understanding of cancers. A human retrovirus was established during 1980-1982 in linkage with a unique human leukemia, concurrently in Japan and USA. This review covers our efforts on the discovery of new retrovirus, Human T-cell Leukemia Virus Type 1 (HTLV-1), first introducing to a new class of retroviruses with a unique regulatory factors, Tax and Rex. Then it is followed by analyses of molecular interaction of the vial Tax with cellular machineries involved in the pathogenesis of Adult T-cell Leukemia (ATL). And then a probable mechanism of pathogenesis of ATL is proposed including recent findings on HBZ after our efforts.
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Affiliation(s)
- Mitsuaki Yoshida
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo, Japan.
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Potential enhancement of osteoclastogenesis by severe acute respiratory syndrome coronavirus 3a/X1 protein. Arch Virol 2009; 154:1457-64. [PMID: 19685004 PMCID: PMC7086770 DOI: 10.1007/s00705-009-0472-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2009] [Accepted: 07/13/2009] [Indexed: 11/01/2022]
Abstract
Severe acute respiratory syndrome coronavirus (SARS-CoV) causes a lung disease with high mortality. In addition, osteonecrosis and bone abnormalities with reduced bone density have been observed in patients following recovery from SARS, which were partly but not entirely explained by the short-term use of steroids. Here, we demonstrate that human monocytes, potential precursors of osteoclasts, partly express angiotensin converting enzyme 2 (ACE2), a cellular receptor of SARS-CoV, and that expression of an accessory protein of SARS-CoV, 3a/X1, in murine macrophage cell line RAW264.7 cells, enhanced NF-kappaB activity and differentiation into osteoclast-like cells in the presence of receptor activator of NF-kappaB ligand (RANKL). Furthermore, human epithelial A549 cells expressed ACE2, and expression of 3a/X1 in these cells up-regulated TNF-alpha, which is known to accelerate osteoclastogenesis. 3a/X1 also enhanced RANKL expression in mouse stromal ST2 cells. These findings indicate that SARS-CoV 3a/X1 might promote osteoclastogenesis by direct and indirect mechanisms.
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15
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The proto-oncogene Bcl3, induced by Tax, represses Tax-mediated transcription via p300 displacement from the human T-cell leukemia virus type 1 promoter. J Virol 2008; 82:11939-47. [PMID: 18815299 DOI: 10.1128/jvi.01356-08] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The etiology of human T-cell leukemia virus type 1 (HTLV-1)-induced adult T-cell leukemia is linked to the expression of the viral oncoprotein Tax. Although the mechanism of retroviral transformation is unknown, Tax interferes with fundamental cellular processes, including proliferation and apoptosis, and these events may directly link Tax to early steps in malignant progression. In this study, we examined the interplay between Tax and the potent proto-oncogene B-cell chronic leukemia protein 3 (Bcl3). Bcl3 is a critical regulator of cell survival and proliferation and is overexpressed in HTLV-1-infected cells. We found that Tax induced Bcl3 expression through stimulation of the NF-kappaB pathway. An intronic NF-kappaB binding site within the Bcl3 gene served as the primary target of Tax-induced NF-kappaB activation. We next considered the consequence of Bcl3 overexpression on Tax function. Interestingly, we found that Bcl3 formed a stable complex with Tax and that this complex potently inhibited Tax-dependent HTLV-1 transcription. Importantly, Bcl3 associated with the HTLV-1 promoter in a Tax-dependent manner and inhibited the binding of the critical cellular coactivator p300. The conserved ankyrin repeat domain of Bcl3 mediated both Tax binding and inhibition of p300 recruitment to the HTLV-1 promoter. Together, these data suggest that Tax-induced Bcl3 overexpression benefits the virus in two important ways. First, Bcl3 may promote cell division and thus clonal proliferation of the virus. Second, Bcl3 may attenuate virion production, facilitating immune evasion. One consequence of this regulatory loop may be Bcl3-induced malignant transformation of the host cell.
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16
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Boxus M, Twizere JC, Legros S, Dewulf JF, Kettmann R, Willems L. The HTLV-1 Tax interactome. Retrovirology 2008; 5:76. [PMID: 18702816 PMCID: PMC2533353 DOI: 10.1186/1742-4690-5-76] [Citation(s) in RCA: 195] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2008] [Accepted: 08/14/2008] [Indexed: 12/22/2022] Open
Abstract
The Tax1 oncoprotein encoded by Human T-lymphotropic virus type I is a major determinant of viral persistence and pathogenesis. Tax1 affects a wide variety of cellular signalling pathways leading to transcriptional activation, proliferation and ultimately transformation. To carry out these functions, Tax1 interacts with and modulates activity of a number of cellular proteins. In this review, we summarize the present knowledge of the Tax1 interactome and propose a rationale for the broad range of cellular proteins identified so far.
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Affiliation(s)
- Mathieu Boxus
- University Academia Wallonie-Europe, Molecular and Cellular Biology at FUSAGx, Gembloux, Belgium.
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17
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Hara T, Matsumura-Arioka Y, Ohtani K, Nakamura M. Role of human T-cell leukemia virus type I Tax in expression of the human telomerase reverse transcriptase (hTERT) gene in human T-cells. Cancer Sci 2008; 99:1155-63. [PMID: 18422743 PMCID: PMC11159262 DOI: 10.1111/j.1349-7006.2008.00798.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 01/08/2008] [Accepted: 01/31/2008] [Indexed: 12/22/2022] Open
Abstract
The viral product Tax encoded by human T-cell leukemia virus type I (HTLV-I) is thought to play a central role in leukemogenesis. Clonal expansion of HTLV-I-infected cells requires the extension of cell division with telomere maintenance, which is regulated by the ribonucleoprotein enzyme telomerase. However, the roles of Tax in the expression of telomerase activity in T-cells remains controversial. Our previous study indicated that expression of the human telomerase reverse transcriptase subunit (hTERT) gene, which determines telomerase activity, is tightly regulated in human T-cells. In the present study, we investigated Tax-mediated regulation of hTERT gene expression by Tax in human T-cells. HTLV-I Tax induced expression of the hTERT gene in human peripheral blood leukocytes. Reporter assays revealed that Tax activated the hTERT promoter in quiescent Kit 225 cells, while the promoter activity was repressed by Tax in proliferating Jurkat cells. Both up-regulation and down-regulation by Tax were mediated through the 43-bp sequences in the promoter, which carried at least two elements that independently functioned as repressors. The two elements bound distinct factors. G1 to S phase transition induced by introduction of either cyclin D2 with cdk4 or p130-specific shRNA also activated the hTERT promoter, implying that activation of the hTERT promoter in quiescent Kit 225 cells is associated with cell cycle progression. Our findings suggest that the cell cycle state critically influences Tax-mediated regulation of hTERT expression.
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Affiliation(s)
- Toshifumi Hara
- Human Gene Sciences Center, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
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18
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Gatza ML, Dayaram T, Marriott SJ. Ubiquitination of HTLV-I Tax in response to DNA damage regulates nuclear complex formation and nuclear export. Retrovirology 2007; 4:95. [PMID: 18081936 PMCID: PMC2234431 DOI: 10.1186/1742-4690-4-95] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2007] [Accepted: 12/14/2007] [Indexed: 01/28/2023] Open
Abstract
Background The HTLV-I oncoprotein, Tax, is a pleiotropic protein whose activity is partially regulated by its ability to interact with, and perturb the functions of, numerous cellular proteins. Tax is predominantly a nuclear protein that localizes to nuclear foci known as Tax Speckled Structures (TSS). We recently reported that the localization of Tax and its interactions with cellular proteins are altered in response to various forms of genotoxic and cellular stress. The level of cytoplasmic Tax increases in response to stress and this relocalization depends upon the interaction of Tax with CRM1. Cellular pathways and signals that regulate the subcellular localization of Tax remain to be determined. However, post-translational modifications including sumoylation and ubiquitination are known to influence the subcellular localization of Tax and its interactions with cellular proteins. The sumoylated form of Tax exists predominantly in the nucleus while ubiquitinated Tax exists predominantly in the cytoplasm. Therefore, we hypothesized that post-translational modifications of Tax that occur in response to DNA damage regulate the localization of Tax and its interactions with cellular proteins. Results We found a significant increase in mono-ubiquitination of Tax in response to UV irradiation. Mutation of specific lysine residues (K280 and K284) within Tax inhibited DNA damage-induced ubiquitination. In contrast to wild-type Tax, which undergoes transient nucleocytoplasmic shuttling in response to DNA damage, the K280 and K284 mutants were retained in nuclear foci following UV irradiation and remained co-localized with the cellular TSS protein, sc35. Conclusion This study demonstrates that the localization of Tax, and its interactions with cellular proteins, are dynamic following DNA damage and depend on the post-translational modification status of Tax. Specifically, DNA damage induces the ubiquitination of Tax at K280 and K284. Ubiquitination of these residues facilitates the dissociation of Tax from sc35-containing nuclear foci, and stimulates nuclear export of Tax through the CRM1 pathway.
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Affiliation(s)
- Michael L Gatza
- Department of Molecular Virology and Microbiology, Interdepartmental Program in Cell and Molecular Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
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19
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Pandya D, Rahman S, Wigdahl B, Khan ZK, Jain P. New insights into the pathogenesis, diagnosis and treatment of human T-cell leukemia virus type 1-induced disease. Future Virol 2007. [DOI: 10.2217/17460794.2.5.481] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
It has been over 25 years since the discovery of human T-cell leukemia virus type 1 (HTLV-1); however, the exact sequence of events that occur during primary infection, clinical latency or the development of disease remains unresolved. The advances in molecular virology and neuroimmunology have contributed significantly to our understanding of HTLV-1 pathogenesis, but also uncovered the complexity of the virus–host interaction both in the peripheral blood and the CNS. Here, we overview the general pathologic features of HTLV-1, molecular mechanisms of oncogenic transformation and characteristics of the host immune response during the associated neuroinflammatory process. We also discuss both current and new approaches in the diagnosis and therapy of HTLV-1 associated diseases – adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Finally, potentially important emerging areas of research that may have an impact on our understanding of the pathogenic mechanism have been briefly introduced.
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Affiliation(s)
- Devanshi Pandya
- Drexel University College of Medicine, Department of Microbiology & Immunology, and, Center for Cancer Biology, Institute for Molecular Medicine & Infectious Disease, Philadelphia, PA 19102, USA
| | - Saifur Rahman
- Drexel University College of Medicine, Department of Microbiology & Immunology, and, Center for Cancer Biology, Institute for Molecular Medicine & Infectious Disease, Philadelphia, PA 19102, USA
| | - Brian Wigdahl
- Drexel University College of Medicine, Department of Microbiology & Immunology, and, Center for Cancer Biology, Institute for Molecular Medicine & Infectious Disease, Philadelphia, PA 19102, USA
| | - Zafar K Khan
- Drexel University College of Medicine, Department of Microbiology & Immunology, and, Center for Cancer Biology, Institute for Molecular Medicine & Infectious Disease, Philadelphia, PA 19102, USA
| | - Pooja Jain
- Drexel University College of Medicine, Department of Microbiology & Immunology, Institute for Molecular Medicine & Infectious Disease, New College Building, Room 18311, 245 North 15th Street, Philadelphia, PA 19102, USA
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20
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Winter HY, Marriott SJ. Human T-cell leukemia virus type 1 Tax enhances serum response factor DNA binding and alters site selection. J Virol 2007; 81:6089-98. [PMID: 17376895 PMCID: PMC1900302 DOI: 10.1128/jvi.02179-06] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Human T-cell leukemia virus type I (HTLV-1) is the etiological agent of adult T-cell leukemia. The viral transforming protein Tax regulates the transcription of viral and cellular genes by interacting with cellular transcription factors and coactivators. The effects of Tax on cellular gene expression have an important impact on HTLV-1-mediated cellular transformation. Expression of the c-fos cellular oncogene is regulated by serum response factor (SRF), and Tax is known to induce c-fos gene expression by activating SRF-responsive transcription. SRF activates cellular gene expression by binding to a consensus DNA sequence (CArG box) located within a serum response element (SRE). Since SRF activates transcription of many growth regulatory genes, this pathway is likely to have a significant impact on Tax-mediated transformation. Here we demonstrate that Tax interacts with SRF and enhances the binding of SRF to SREs located in the c-fos, Nur77, and viral promoters. Also, we establish that in the presence of Tax, SRF selects more divergent CArG box sequences than in the absence of Tax, revealing a novel mechanism for regulating SRF-responsive gene expression. Finally, increased association of SRF with chromatin and specific promoters was observed in Tax-expressing cells, correlating with increased c-fos and Nur77 mRNA levels in Tax-expressing cells. These results suggest that Tax activates SRF-responsive transcription by enhancing its binding affinity to multiple different SRE sequences.
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Affiliation(s)
- Heather Y Winter
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
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21
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Kanzawa N, Nishigaki K, Hayashi T, Ishii Y, Furukawa S, Niiro A, Yasui F, Kohara M, Morita K, Matsushima K, Le MQ, Masuda T, Kannagi M. Augmentation of chemokine production by severe acute respiratory syndrome coronavirus 3a/X1 and 7a/X4 proteins through NF-kappaB activation. FEBS Lett 2006; 580:6807-12. [PMID: 17141229 PMCID: PMC7094718 DOI: 10.1016/j.febslet.2006.11.046] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Revised: 11/06/2006] [Accepted: 11/16/2006] [Indexed: 01/20/2023]
Abstract
Severe acute respiratory syndrome (SARS) is characterized by rapidly progressing respiratory failure resembling acute/adult respiratory distress syndrome (ARDS) associated with uncontrolled inflammatory responses. Here, we demonstrated that, among five accessory proteins of SARS coronavirus (SARS-CoV) tested, 3a/X1 and 7a/X4 were capable of activating nuclear factor kappa B (NF-kappaB) and c-Jun N-terminal kinase (JNK), and significantly enhanced interleukin 8 (IL-8) promoter activity. Furthermore, 3a/X1 and 7a/X4 expression in A549 cells enhanced production of inflammatory chemokines that were known to be up-regulated in SARS-CoV infection. Our results suggest potential involvement of 3a/X1 and 7a/X4 proteins in the pathological inflammatory responses in SARS.
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Affiliation(s)
- Noriyuki Kanzawa
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Kazuo Nishigaki
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Takaya Hayashi
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Yuichi Ishii
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Souichi Furukawa
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Ayako Niiro
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Fumihiko Yasui
- Department of Microbiology and Cell Biology, The Tokyo Metropolitan Institute of Medical Science, Tokyo 113-8613, Japan
| | - Michinori Kohara
- Department of Microbiology and Cell Biology, The Tokyo Metropolitan Institute of Medical Science, Tokyo 113-8613, Japan
| | - Kouichi Morita
- Department of Virology, Institute of Tropical Medicine, Nagasaki University, Nagasaki 852-8523, Japan
| | - Kouji Matsushima
- Department of Molecular Preventive Medicine, School of Medicine, The University of Tokyo, 113-0033, Japan
| | - Mai Quynh Le
- Department of Virology, National Institute of Hygiene and Epidemiology (NIHE), Hanoi, Viet Nam
| | - Takao Masuda
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
| | - Mari Kannagi
- Department of Immunotherapeutics, Tokyo Medical and Dental University, Graduate School, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8519, Japan
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22
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Konson A, Mahajna JA, Danon A, Rimon G, Agbaria R. The involvement of nuclear factor-kappa B in cyclooxygenase-2 overexpression in murine colon cancer cells transduced with herpes simplex virus thymidine kinase gene. Cancer Gene Ther 2006; 13:1093-104. [PMID: 16841079 DOI: 10.1038/sj.cgt.7700983] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
We have previously reported that transduction of murine colon cancer cells (MC38) with herpes simplex virus thymidine kinase (HSV-tk) gene results in a significant enhancement of tumor growth rate in vivo and overexpression of cyclooxygenase-2 (COX-2). Our current study aimed to investigate the involvement of nuclear factor-kappa B (NF-kappaB), a pivotal transcriptional regulator of COX-2, in the upregulation of COX-2 expression by HSV-tk. It was found that HSV-tk gene transduction of MC38 cells results in significantly enhanced NF-kappaB activity, increased phosphorylation and degradation of inhibitor-kappa Balpha (IkappaBalpha) and enhanced translocation of NF-kappaB to the nucleus. Treatment of HSV-tk-transduced MC38 cells with sulfasalazine, a potent NF-kappaB inhibitor, led to dose-dependent inhibition of NF-kappaB activity, IkappaB phosphorylation and nuclear translocation of NF-kappaB, accompanied by significantly decreased COX-2 expression and reduced release of prostaglandin E2. Transient transfection experiments with COX-2 promoter constructs fused to luciferase reporter gene revealed that mutation in NF-kappaB-responsive element of COX-2 promoter significantly reduced promoter activity in HSV-tk-transduced MC38 and COS-7 cells, whereas it had no effect on promoter activity in the respective wild-type cells. At last, it was found that HSV-tk gene transduction causes significant enhancement of NF-kappaB activity and COX-2 expression in two additional tumor cell lines, 9L and T24. These findings suggest that HSV-tk gene transduction results in NF-kappaB pathway activation, which is essential for COX-2 overexpression by HSV-tk.
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Affiliation(s)
- A Konson
- Department of Clinical Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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23
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Gatza ML, Marriott SJ. Genotoxic stress and cellular stress alter the subcellular distribution of human T-cell leukemia virus type 1 tax through a CRM1-dependent mechanism. J Virol 2006; 80:6657-68. [PMID: 16775353 PMCID: PMC1488944 DOI: 10.1128/jvi.02270-05] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Accepted: 04/14/2006] [Indexed: 12/17/2022] Open
Abstract
Human T-cell leukemia virus type 1 Tax is a predominantly nuclear viral oncoprotein that colocalizes with cellular proteins in nuclear foci known as Tax speckled structures (TSS). Tax is also diffusely distributed throughout the cytoplasm, where it interacts with and affects the functions of cytoplasmic cellular proteins. Mechanisms that regulate the distribution of Tax between the cytoplasm and nucleus remain to be identified. Since Tax has been shown to promote genome instability by perturbing cell cycle progression and DNA repair mechanisms following DNA damage, we examined the effect of genotoxic stress on the subcellular distribution and interacting partners of Tax. Tax localization was altered in response to various forms of cellular stress, resulting in an increase in cytoplasmic Tax and a decrease in Tax speckled structures. Concomitantly, colocalization of Tax with sc35 (a TSS protein) decreased following stress. Tax translocation required the CRM1 nuclear export pathway, and a transient interaction between Tax and CRM1 was observed following stress. These results suggest that the subcellular distribution of Tax and the interactions between Tax and cellular proteins respond dynamically to cellular stress. Changes in Tax distribution and interacting partners are likely to affect cellular processes that regulate cellular transformation.
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Affiliation(s)
- Michael L Gatza
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, One Baylor Plaza MS-385, Houston, TX 77030, USA
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24
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Yamakuni T, Aoki K, Nakatani K, Kondo N, Oku H, Ishiguro K, Ohizumi Y. Garcinone B reduces prostaglandin E2 release and NF-κB-mediated transcription in C6 rat glioma cells. Neurosci Lett 2006; 394:206-10. [PMID: 16260090 DOI: 10.1016/j.neulet.2005.10.023] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2005] [Revised: 10/08/2005] [Accepted: 10/11/2005] [Indexed: 12/30/2022]
Abstract
In the course of our survey of natural compounds inhibiting prostaglandin E2 release and/or lipopolysaccharide (LPS)-induced transcriptional stimulation via NF-kappaB, a central regulator of inflammatory genes, from natural resources, we found garcinone B, a xanthone from callus tissue culture of Hypericum patulum, as a compound with such pharmacological activities, that is a derivative of gamma-mangostin which potently inhibits COX-1 and COX-2 activities to reduce PGE2 release from C6 rat glioma cells, and inhibits IKK activity to prevent NF-kappaB-dependent COX-2 gene transcription. Garcinone B, to a lesser extent, reduced A23187-induced increase in prostaglandin E2 release than gamma-mangostin and its structurally related compound, patulone, in C6 cells. This compound also prevented LPS-induced stimulation of NF-kappaB-dependent transcription. These results suggest that garcinone B becomes a unique pharmacological tool to investigate intracellular signaling pathways involved in inflammation.
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Affiliation(s)
- Tohru Yamakuni
- Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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25
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Yoshida M. Discovery of HTLV-1, the first human retrovirus, its unique regulatory mechanisms, and insights into pathogenesis. Oncogene 2005; 24:5931-7. [PMID: 16155600 DOI: 10.1038/sj.onc.1208981] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
I briefly review the discovery and characterization of the first human retrovirus, human T-cell leukemia virus type 1, focusing on contributions from Japanese researchers. The unique regulatory mechanisms for the viral regulation with Tax and Rex, etiology of ATL and possible leukemogenic mechanism with Tax are also discussed briefly.
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Affiliation(s)
- Mitsuaki Yoshida
- Banyu Tsukuba Research Institute, Banyu Pharmaceutical Co., Ltd., 3 Ohkubo, Tsukuba, Ibaraki 300-2611, Japan.
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26
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Konnai S, Usui T, Ikeda M, Kohara J, Hirata T, Okada K, Ohashi K, Onuma M. Tumor necrosis factor-alpha up-regulation in spontaneously proliferating cells derived from bovine leukemia virus-infected cattle. Arch Virol 2005; 151:347-60. [PMID: 16155729 DOI: 10.1007/s00705-005-0622-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2005] [Accepted: 05/19/2005] [Indexed: 10/25/2022]
Abstract
We previously reported that tumor necrosis factor alpha (TNF-alpha) was one of the cytokines that contributed to the leukemogenesis caused by bovine leukemia virus (BLV). To determine if the spontaneous cell proliferation observed in the late disease stages, such as persistent lymphocytosis and lymphosarcoma, correlated with the expression level of TNF-alpha, we analyzed the mRNA expression levels for TNF-alpha in spontaneously proliferating PBMCs derived from BLV-infected cattle. The mean mRNA expression level for TNF-alpha was higher in the spontaneously proliferating PBMCs derived from BLV-infected cattle than in non-spontaneously proliferating PBMCs from normal cattle. The TNF-alpha protein level in the PBMCs was determined by flow cytometric analysis, and it was noted that most of the cells expressing membrane-bound TNF-alpha in the spontaneously proliferating cells were CD5+ or sIgM+-cells. Additionally, in order to determine if this spontaneous proliferation can be blocked by anti-bovine TNF-alpha MAb, the spontaneously proliferating PBMCs from a BLV-infected cattle were cultured in the presence of the MAb. The addition of this MAb at the beginning of the 72 h-cultivation clearly inhibited spontaneous proliferation of cells in a dose-dependent manner, indicating the direct involvement of TNF-alpha in the spontaneous proliferation of PBMCs during the late disease stage. These data suggest that an aberrant expression of TNF-alpha might contribute to the progression of bovine leukosis in animals which develop persistent lymphocytosis of B-cells or B-cell lymphosarcoma.
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Affiliation(s)
- S Konnai
- Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Hokkaido, Japan.
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27
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Yamaguchi T, Maeda Y, Ueda S, Hijikata Y, Morita Y, Miyatake JI, Matsuda M, Kanamaru A. Dichotomy of all-trans retinoic acid inducing signals for adult T-cell leukemia. Leukemia 2005; 19:1010-7. [PMID: 15843825 DOI: 10.1038/sj.leu.2403760] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We previously reported that all-trans retinoic acid (ATRA) inhibits growth in human T-cell leukemia virus type 1 (HTLV-1)-positive T-cell lines and fresh cells from patients with adult T-cell leukemia. However, the mechanism of this inhibition is not clear. In the present study, we observed that NF-kappaB transcriptional activity as well as cell growth decreased significantly in HTLV-1-positive T-cell lines in the presence of ATRA. Furthermore, we observed that ATRA reduced HTLV-1 proviral DNA, HTLV-1 genes (gag, tax, or pol mRNA) using the real-time quantitative polymerase chain reaction. SIL-2R was reduced by ATRA in both protein level (culture supernantant) and mRNA level in HTLV-1-positive T-cell lines. Interestingly, ATRA significantly inhibited RT activity similar to azidothimidine (AZT) in HTLV-1-positive T-cell lines. Moreover, AZT inhibited proviral DNA but not NF-kappaB transcriptional activity, and sIL-2R on HTLV-1; however, ATRA inhibited of NF-kappaB, proviral DNA and sIL-2R on HTLV-1. These results suggested that the decrease in sIL-2R induced by ATRA may be caused by the actions of a NF-kappaB inhibitor acting on the NF-kappaB/sIL-2R signal pathway. These results suggested that ATRA could have two roles, as a NF-kappaB inhibitor and as an RT inhibitor.
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Affiliation(s)
- T Yamaguchi
- Department of Hematology, Kinki University School of Medicine, Osaka 589-8511, Japan
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28
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Kfoury Y, Nasr R, Hermine O, de Thé H, Bazarbachi A. Proapoptotic regimes for HTLV-I-transformed cells: targeting Tax and the NF-κB pathway. Cell Death Differ 2005; 12 Suppl 1:871-7. [PMID: 15846376 DOI: 10.1038/sj.cdd.4401624] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Y Kfoury
- Department of Internal Medicine, American University of Beirut, Beirut, Lebanon
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29
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Azran I, Jeang KT, Aboud M. High levels of cytoplasmic HTLV-1 Tax mutant proteins retain a Tax-NF-κB-CBP ternary complex in the cytoplasm. Oncogene 2005; 24:4521-30. [PMID: 15806143 DOI: 10.1038/sj.onc.1208645] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The oncogenic potential of HTLV-1 Tax protein is partially ascribed to its capacity to activate NF-kappaB. The current view is that Tax acts first in the cytoplasm to dissociate NF-kappaB factors from the IkappaB proteins and enable their nuclear translocation, then Tax links p65(RelA), within the nucleus, to CBP/p300 and P/CAF, which are essential for its optimal transcriptional activity. Our present study challenges the paradigm that Tax-p65(RelA)-CBP/p300 assembly occurs in the nucleus. Using Tax mutants defective for nuclear localization we show that at low levels these mutants induce the nuclear translocation of NF-kappaB factors but not their transcriptional activity, whereas at high levels they trap CBP and free p65(RelA) in the cytoplasm and block, thereby, their transcriptional function. In contrast, wild-type (w.t.) Tax strongly stimulated NF-kappaB-dependent gene expression in all tested experimental settings. These data suggest that the Tax-p65(RelA)-CBP ternary complex is established in the cytoplasm rather than in the nucleus. When this complex is formed with w.t. Tax, the entire moiety translocates into the nucleus and exerts high transcriptional activity. However, if the complex is formed with the cytoplasmic Tax mutants, the resulting moiety is retained in the cytoplasm and is, therefore, devoid of transcriptional activity.
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Affiliation(s)
- Inbal Azran
- Department of Microbiology and Immunology, Cancer Research Center, Faculty of Health Sciences, Ben-Gurion University of Negev, Beer Sheva 84105, Israel
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Wu P, Wang P. Per-Arnt-Sim domain-dependent association of cAMP-phosphodiesterase 8A1 with IkappaB proteins. Proc Natl Acad Sci U S A 2004; 101:17634-9. [PMID: 15596729 PMCID: PMC539753 DOI: 10.1073/pnas.0407649101] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Phosphodiesterase (PDE) 8A1 is a cAMP-specific PDE isozyme characterized by the presence of a Per-Arnt-Sim (PAS) domain. However, the function(s) of the PAS domain has remained unknown. In this study, using a lysate of HEK293 cells overexpressing recombinant human PDE8A1, we detected a physical association between PDE8A1 and endogenous IkappaBbeta by an antibody array technique. The association was specific for PDE8A1 and depended on the presence of the PAS domain. Subsequent coimmunoprecipitation experiments revealed that, in addition to IkappaBbeta, other IkappaB family members examined (p105, p100, and IkappaBalpha) also associated with PDE8A1. Furthermore, it was found that PDE8A1 competed with the p65/p50 NF-kappaB for IkappaBbeta binding. Taken together, these data indicate that PDE8A1, through its PAS domain, may bind with IkappaB proteins in a region containing their ankyrin repeats. Functionally, in vitro and in vivo experiments demonstrated that the association with IkappaB greatly enhanced the enzyme activity of PDE8A1. However, the PDE8A1-IkappaB association did not affect NF-kappaB activation. The biological role of the PDE8A1-IkappaB association remains to be elucidated.
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Affiliation(s)
- Ping Wu
- Department of Inflammation and Infection, Schering-Plough Research Institute, Kenilworth, NJ 07033, USA
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Nakanishi H, Kaibori M, Teshima S, Yoshida H, Kwon AH, Kamiyama Y, Nishizawa M, Ito S, Okumura T. Pirfenidone inhibits the induction of iNOS stimulated by interleukin-1beta at a step of NF-kappaB DNA binding in hepatocytes. J Hepatol 2004; 41:730-6. [PMID: 15519644 DOI: 10.1016/j.jhep.2004.07.007] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/19/2004] [Revised: 06/09/2004] [Accepted: 07/02/2004] [Indexed: 02/06/2023]
Abstract
BACKGROUND/AIMS Pirfenidone has antiinflammatory effects in animals with endotoxemia. We reported that pirfenidone inhibits the enhancement of inflammatory cytokines and inducible nitric oxide synthase (iNOS) in liver of endotoxin-treated rats, leading to the prevention of hepatic injury. However, the mechanisms involved in suppression of these gene inductions are obscure. Studies were performed to investigate whether pirfenidone directly influences iNOS induction in hepatocytes. METHODS Cultured hepatocytes were treated with interleukin-1beta (IL-1beta) in the presence and absence of pirfenidone, and iNOS induction and its signal including NF-kappaB were analyzed. RESULTS Pirfenidone inhibited the induction of iNOS mRNA and protein, resulting in the decrease of nitric oxide production. Gel shift assay demonstrated that pirfenidone inhibited the activation of NF-kappaB. Consistent with this observation, transfection experiments revealed that pirfenidone decreased transcriptional activation of iNOS gene promoter. In contrast, pirfenidone had no effect on the degradation of IkappaB, and could not prevent nuclear translocation of p50/p65. Finally, pirfenidone inhibited the activation of Akt and up-regulation of IL-1 receptor stimulated by IL-1beta. CONCLUSIONS Results indicate that pirfenidone inhibits the induction of iNOS gene expression at a step of NF-kappaB DNA binding, but not its nuclear translocation, partly through the inhibition of IL-1 receptor induction in hepatocytes.
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Affiliation(s)
- Hideki Nakanishi
- The First Department of Surgery, Kansai Medical University, 10-15 Fumizonocho, Moriguchi, Osaka 570-8506, Japan
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Azran I, Schavinsky-Khrapunsky Y, Aboud M. Role of Tax protein in human T-cell leukemia virus type-I leukemogenicity. Retrovirology 2004; 1:20. [PMID: 15310405 PMCID: PMC514576 DOI: 10.1186/1742-4690-1-20] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2004] [Accepted: 08/13/2004] [Indexed: 11/17/2022] Open
Abstract
HTLV-1 is the etiological agent of adult T-cell leukemia (ATL), the neurological syndrome TSP/HAM and certain other clinical disorders. The viral Tax protein is considered to play a central role in the process leading to ATL. Tax modulates the expression of many viral and cellular genes through the CREB/ATF-, SRF- and NF-κB-associated pathways. In addition, Tax employs the CBP/p300 and p/CAF co-activators for implementing the full transcriptional activation competence of each of these pathways. Tax also affects the function of various other regulatory proteins by direct protein-protein interaction. Through these activities Tax sets the infected T-cells into continuous uncontrolled replication and destabilizes their genome by interfering with the function of telomerase and topoisomerase-I and by inhibiting DNA repair. Furthermore, Tax prevents cell cycle arrest and apoptosis that would otherwise be induced by the unrepaired DNA damage and enables, thereby, accumulation of mutations that can contribute to the leukemogenic process. Together, these capacities render Tax highly oncogenic as reflected by its ability to transform rodent fibroblasts and primary human T-cells and to induce tumors in transgenic mice. In this article we discuss these effects of Tax and their apparent contribution to the HTLV-1 associated leukemogenic process. Notably, however, shortly after infection the virus enters into a latent state, in which viral gene expression is low in most of the HTLV-1 carriers' infected T-cells and so is the level of Tax protein, although rare infected cells may still display high viral RNA. This low Tax level is evidently insufficient for exerting its multiple oncogenic effects. Therefore, we propose that the latent virus must be activated, at least temporarily, in order to elevate Tax to its effective level and that during this transient activation state the infected cells may acquire some oncogenic mutations which can enable them to further progress towards ATL even if the activated virus is re-suppressed after a while. We conclude this review by outlining an hypothetical flow of events from the initial virus infection up to the ultimate ATL development and comment on the risk factors leading to ATL development in some people and to TSP/HAM in others.
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Affiliation(s)
- Inbal Azran
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Yana Schavinsky-Khrapunsky
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
| | - Mordechai Aboud
- Department of Microbiology and Immunology and Cancer Research Center, Faculty of Health Sciences, Ben Gurion University of the Negev, Beer Sheva 84105, Israel
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Nakatani K, Yamakuni T, Kondo N, Arakawa T, Oosawa K, Shimura S, Inoue H, Ohizumi Y. γ-Mangostin Inhibits Inhibitor-κB Kinase Activity and Decreases Lipopolysaccharide-Induced Cyclooxygenase-2 Gene Expression in C6 Rat Glioma Cells. Mol Pharmacol 2004; 66:667-74. [PMID: 15322259 DOI: 10.1124/mol.104.002626] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We investigated the effect of gamma-mangostin purified from the fruit hull of the medicinal plant Garcinia mangostana on spontaneous prostaglandin E(2) (PGE(2)) genase release and inducible cyclooxy-2 (COX-2) gene expression in C6 rat glioma cells. An 18-h treatment with gamma-mangostin potently inhibited spontaneous PGE(2) release in a concentration-dependent manner with the IC(50) value of approximately 2 microM, without affecting the cell viability even at 30 microM. By immunoblotting and reverse-transcription polymerase chain reaction, we showed that gamma-mangostin concentration-dependently inhibited lipopolysaccharide (LPS)-induced expression of COX-2 protein and its mRNA, but not those of constitutive COX-1 cyclooxygenase. Because LPS is known to stimulate inhibitor kappaB (IkappaB) kinase (IKK)-mediated phosphorylation of IkappaB followed by its degradation, which in turn induces nuclear factor (NF)-kappaB nuclear translocation leading to transcriptional activation of COX-2 gene, the effect of gamma-mangostin on the IKK/IkappaB cascade controlling the NF-kappaB activation was examined. An in vitro IKK assay using IKK protein immunoprecipitated from C6 cell extract showed that this compound inhibited IKK activity in a concentration-dependent manner, with the IC(50) value of approximately 10 microM. Consistently gamma-mangostin was also observed to decrease the LPS-induced IkappaB degradation and phosphorylation in a concentration-dependent manner, as assayed by immunoblotting. Furthermore, luciferase reporter assays showed that gamma-mangostin reduced the LPS-inducible activation of NF-kappaB-and human COX-2 gene promoter region-dependent transcription. gamma-Mangostin also inhibited rat carrageenan-induced paw edema. These results suggest that gamma-mangostin directly inhibits IKK activity and thereby prevents COX-2 gene transcription, an NF-kappaB target gene, probably to decrease the inflammatory agent-stimulated PGE(2) production in vivo, and is a new useful lead compound for anti-inflammatory drug development.
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Affiliation(s)
- Keigo Nakatani
- Department of Pharmaceutical Molecular Biology, Graduate School of Pharmaceutical Sciences, Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai 980-8578, Japan
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Shimizu T, Kawakita S, Li QH, Fukuhara S, Fujisawa JI. Human T-cell leukemia virus type 1 Tax protein stimulates the interferon-responsive enhancer element via NF-kappaB activity. FEBS Lett 2003; 539:73-7. [PMID: 12650929 DOI: 10.1016/s0014-5793(03)00200-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Gene expression in Rat-1 fibroblast cells transformed by Tax from human T-cell leukemia virus type 1 was studied using the reverse transcriptase polymerase chain reaction differential display technique. The analysis revealed eight genes that were upregulated and one gene that was suppressed in Tax-transformed cells. Interestingly, at least four of the upregulated genes were interferon-stimulated genes. Promoter analysis of the 2',5'-oligoadenylate synthetase gene, which was activated in both Tax-transformed Rat-1 cells and primary adult T-cell leukemia cells, demonstrated that Tax indirectly activates its interferon-responsive enhancer element in a nuclear factor-kappaB pathway-dependent manner, indicating a close association of interferon signaling with the transformation by Tax.
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Affiliation(s)
- Toshiki Shimizu
- Department of Microbiology, Kansai Medical University, Fumizono-cho 10-15, Moriguchi, Osaka, Japan
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Shibanuma M, Kim-Kaneyama JR, Ishino K, Sakamoto N, Hishiki T, Yamaguchi K, Mori K, Mashimo JI, Nose K. Hic-5 communicates between focal adhesions and the nucleus through oxidant-sensitive nuclear export signal. Mol Biol Cell 2003; 14:1158-71. [PMID: 12631731 PMCID: PMC151587 DOI: 10.1091/mbc.02-06-0099] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2002] [Revised: 10/30/2002] [Accepted: 11/25/2002] [Indexed: 11/11/2022] Open
Abstract
hic-5 was originally isolated as an H(2)O(2)-inducible cDNA clone whose product was normally found at focal adhesions. In this study, we found that Hic-5 accumulated in the nucleus in response to oxidants such as H(2)O(2). Other focal adhesion proteins including paxillin, the most homologous to Hic-5, remained in the cytoplasm. Mutation analyses revealed that the C- and N-terminal halves of Hic-5 contributed to its nuclear localization in a positive and negative manner, respectively. After the finding that leptomycin B (LMB), an inhibitor of nuclear export signal (NES), caused Hic-5 to be retained in the nucleus, Hic-5 was demonstrated to harbor NES in the N-terminal, which was sensitive to oxidants, thereby regulating the nuclear accumulation of Hic-5. NES consisted of a leucine-rich stretch and two cysteines with a limited similarity to Yap/Pap-type NES. In the nucleus, Hic-5 was suggested to participate in the gene expression of c-fos. Using dominant negative mutants, we found that Hic-5 was actually involved in endogenous c-fos gene expression upon H(2)O(2) treatment. Hic-5 was thus proposed as a focal adhesion protein with the novel aspect of shuttling between focal adhesions and the nucleus through an oxidant-sensitive NES, mediating the redox signaling directly to the nucleus.
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Affiliation(s)
- Motoko Shibanuma
- Department of Microbiology, Showa University School of Pharmaceutical Sciences, Hatanodai 1-5-8, Shinagawa-ku, Tokyo, Japan.
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Wilson KC, Center DM, Cruikshank WW, Zhang Y. Binding of HTLV-1 tax oncoprotein to the precursor of interleukin-16, a T cell PDZ domain-containing protein. Virology 2003; 306:60-7. [PMID: 12620798 DOI: 10.1016/s0042-6822(02)00056-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
HTLV-1 Tax oncoprotein interacts with various cellular factors and modulates transcription and the cell cycle. In that role it is sufficient to create T cell malignancies in the absence of HTLV-1 infection. HTLV-1 Tax protein has been reported to bind to cellular proteins containing PDZ domains in vitro. The precursor of human interleukin 16, pro-IL-16, is an abundant cellular protein present in human peripheral blood T cells. Pro-IL-16 contains three PDZ domains. It has been shown that expression of pro-IL-16 in pro-IL-16 negative cells induces a G(0)/G(1) arrest in the cell cycle. The current studies demonstrate that Tax binds to pro-IL-16 in HTLV-1 infected human T cells. We mapped the Tax binding site to the first PDZ domain of pro-IL-16. Over-expression of Tax in COS cells resulted in fewer cells in G(0)/G(1) consistent with its activity to induce G(1)- to S-phase progression in lymphocytes, while over-expression of pro-IL-16 in COS cells resulted in G(0)/G(1) arrest. Co-expression of wild type Tax with pro-IL-16 in COS cells negated the effects of pro-IL-16, an effect not observed with Tax mutated at its PDZ binding C-terminus. These results suggest that one of the effects of Tax on growth deregulation in HTLV-1 infected T cells might be mediated by its binding to pro-IL-16.
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Affiliation(s)
- Kevin C Wilson
- The Pulmonary Center and Department of Medicine, Boston University School of Medicine, Boston, MA 02118, USA
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Tzagarakis-Foster C, Geleziunas R, Lomri A, An J, Leitman DC. Estradiol represses human T-cell leukemia virus type 1 Tax activation of tumor necrosis factor-alpha gene transcription. J Biol Chem 2002; 277:44772-7. [PMID: 12237295 DOI: 10.1074/jbc.m205355200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adult T-cell leukemia is caused by human T-cell leukemia virus type I (HTLV-I). The HTLV-I Tax protein is essential for clinical manifestations because it activates viral and cellular gene transcription. Tax enhances production of tumor necrosis factor-alpha (TNF-alpha), which may lead to bone and joint destruction. Because estrogens might prevent osteoporosis by repressing TNF-alpha gene transcription, we investigated whether estrogens inhibit the transcriptional effects of Tax on the TNF-alpha promoter. Tax activated the -1044, -163, and -125 TNF-alpha promoters by 9-25-fold but not the -82 promoter, demonstrating that Tax activation requires the -125 to -82 region, known as the TNF response element (TNF-RE). Three copies of the TNF-RE upstream of the minimal thymidine kinase promoter conferred a similar magnitude of activation by Tax. We demonstrated that c-Jun, NFkappaB, p50, and p65 interact with and activate the TNF-RE by using mutational analysis of the TNF-RE, Tax mutants that selectively activate NFkappaB or the cAMP-response element binding protein/activating transcription factor pathway, and gel shift assays with nuclear extracts. Estradiol markedly repressed Tax-activated transcription of the TNF-alpha gene with estrogen receptor (ER) alpha or beta. Nuclear extracts from U2OS cells stably transfected with ER(alpha) demonstrated that ERs interact with the TNF-RE. Our studies provide evidence that ERs repress Tax-activated TNF-alpha transcription by interacting with a c-Jun and NFkappaB platform on the TNF-RE. Estrogens may ameliorate bone and inflammatory joint diseases in patients infected with HTLV-I by repressing transcription of the TNF-alpha gene.
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Affiliation(s)
- Christina Tzagarakis-Foster
- Department of Obstetrics, Gynecology and Reproductive Sciences, Center for Reproductive Sciences, University of California, San Francisco 94143-0556, USA
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Abstract
Most current classifications of lymphoid neoplasms define the tumors based on the cell of origin, phenotype, genetic abnormalities, and clinical features. Here it is proposed that human lymphocytic tumors can be categorized based on the propensity and capacity of the tumor cells to undergo apoptosis. The first category is defined by malignant cells that are resistant to apoptosis due to expression of anti-apoptotic factors such as bcl-2 and cellular inhibitors of apoptosis (IAPs). These tumors would include CLL and follicular lymphomas, as well as some malignancies in which the tumor cells are infected by viruses that co-opt cell survival pathways, such as human T-cell leukemia/lymphoma virus (HTLV)-1. The second category, in which the malignant cells are apoptosis-prone, would include tumors arising in the context of impaired cytotoxic T-cell function. These neoplasms would include some human immunodeficiency virus (HIV)-related lymphomas such as Burkitt's lymphoma, and post-transplantation lymphomas. The third category would include neoplasms of intermediate sensitivity to apoptosis, some of which are associated with infection such as mucosa-associated lymphoid tissue (MALT) lymphomas of the stomach. Although this classification is tentative, it should evolve in parallel with our understanding of pathogenic mechanisms in lymphoid neoplasia, and provides a novel framework with which to consider the appropriateness of specific therapeutic strategies. Distinctions among lymphocytic tumors in terms of the likelihood of response to therapies such as antisense to bcl-2 related proteins, inhibitors of NF-kappa B activity, and new approaches aimed at bolstering the host's immune response, would cross standard classifications based on the T or B-cell origin of the tumor cells.
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MESH Headings
- Apoptosis
- Gene Expression Regulation, Neoplastic
- Genes, bcl-2/genetics
- Humans
- Infections
- Leukemia, Lymphocytic, Chronic, B-Cell/classification
- Leukemia, Lymphocytic, Chronic, B-Cell/physiopathology
- Leukemia, Lymphoid/classification
- Leukemia, Lymphoid/physiopathology
- T-Lymphocytes, Cytotoxic/physiology
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Affiliation(s)
- Elaine J Schattner
- Division of Hematology and Medical Oncology, Department of Medicine, Room C-640, Weill Medical College, USA.
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Hatta Y, Koeffler HP. Role of tumor suppressor genes in the development of adult T cell leukemia/lymphoma (ATLL). Leukemia 2002; 16:1069-85. [PMID: 12040438 DOI: 10.1038/sj.leu.2402458] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2001] [Accepted: 12/31/2001] [Indexed: 01/11/2023]
Abstract
Adult T cell leukemia/lymphoma (ATLL) is one of the peripheral T cell malignant neoplasms strongly associated with human T cell leukemia virus type-I (HTLV-I). Although the viral transactivating protein Tax has been proposed to play a critical role in leukemogeneis as shown by its transforming activity in various experimental systems, additional cellular events are required for the development of ATLL. One of the genetic events in ATLL is inactivation of tumor suppressor genes. Among many candidates for tumor suppressor genes, the main genetic events have been reported to center around the cyclin-dependent kinase inhibitors ((CDKIs) p15INK4A, p16INK4B, p18INK4C, p19INK4D, p21WAF1, p27KIP1, and p57KIP2), p53 and Rb genes; all of them play a major regulatory role during G1 to S transition in the cell cycle. Acute/lymphomatous ATLL has frequent alterations of p15 (20%) and p16 (28-67%), while chronic/smoldering ATLL has fewer abnormalities of p15 (0-13%) and p16 (5-26%). Most of these changes are deletion of the genes; fewer samples have mutations. ATLL patients with deleted p15 and/or p16 genes have significantly shorter survival than those individuals with both genes preserved. Although genetic alterations of p18, p19, p21, p27 have rarely been reported, inactivation of these genes may contribute to the development of ATLL because low expression levels of these genes seem to mark ATLL. The p53 gene is mutated in 10-50% of acute/lymphomatous ATLL. Functional impairment of the p53 protein, even if the gene has wild-type sequences, has been suggested in HTLV-I infected cells. Each of these genetic events are mainly found in acute/lymphomatous ATLL, suggesting that alterations of these genes may be associated with transformation to an aggressive phenotype. The Rb tumor suppressor gene is infrequently structurally altered, but one half of ATLL cases have lost expression of this key protein. Notably, alterations of one of the CDKIs, p53 and Rb genes appear to obviate the need for inactivation of other genes in the same pathway. A novel tumor suppressor gene on chromosome 6q may also have a critical role in the pathogenesis of ATLL. Taken together, tumor suppressor genes are frequently altered in acute/lymphomatous ATLL and their alteration is probably the driving force fueling the transition from chronic/smoldering to acute/lymphomatous ATLL.
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Affiliation(s)
- Y Hatta
- First Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan
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Grant C, Barmak K, Alefantis T, Yao J, Jacobson S, Wigdahl B. Human T cell leukemia virus type I and neurologic disease: events in bone marrow, peripheral blood, and central nervous system during normal immune surveillance and neuroinflammation. J Cell Physiol 2002; 190:133-59. [PMID: 11807819 DOI: 10.1002/jcp.10053] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Human T cell lymphotropic/leukemia virus type I (HTLV-I) has been identified as the causative agent of both adult T cell leukemia (ATL) and HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Although the exact sequence of events that occur during the early stages of infection are not known in detail, the initial route of infection may predetermine, along with host, environmental, and viral factors, the subset of target cells and/or the primary immune response encountered by HTLV-I, and whether an HTLV-I-infected individual will remain asymptomatic, develop ATL, or progress to the neuroinflammatory disease, HAM/TSP. Although a large number of studies have indicated that CD4(+) T cells represent an important target for HTLV-I infection in the peripheral blood (PB), additional evidence has accumulated over the past several years demonstrating that HTLV-I can infect several additional cellular compartments in vivo, including CD8(+) T lymphocytes, PB monocytes, dendritic cells, B lymphocytes, and resident central nervous system (CNS) astrocytes. More importantly, extensive latent viral infection of the bone marrow, including cells likely to be hematopoietic progenitor cells, has been observed in individuals with HAM/TSP as well as some asymptomatic carriers, but to a much lesser extent in individuals with ATL. Furthermore, HTLV-I(+) CD34(+) hematopoietic progenitor cells can maintain the intact proviral genome and initiate viral gene expression during the differentiation process. Introduction of HTLV-I-infected bone marrow progenitor cells into the PB, followed by genomic activation and low level viral gene expression may lead to an increase in proviral DNA load in the PB, resulting in a progressive state of immune dysregulation including the generation of a detrimental cytotoxic Tax-specific CD8(+) T cell population, anti-HTLV-I antibodies, and neurotoxic cytokines involved in disruption of myelin-producing cells and neuronal degradation characteristic of HAM/TSP.
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Affiliation(s)
- Christian Grant
- Laboratory for Molecular Retrovirology and Viral Neuropathogenesis, Department of Microbiology and Immunology, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania 17033, USA
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Kataoka K, Handa H, Nishizawa M. Induction of cellular antioxidative stress genes through heterodimeric transcription factor Nrf2/small Maf by antirheumatic gold(I) compounds. J Biol Chem 2001; 276:34074-81. [PMID: 11429414 DOI: 10.1074/jbc.m105383200] [Citation(s) in RCA: 111] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gold(I)-containing compounds have long been used in the treatment of rheumatoid arthritis (RA), but the molecular mechanism of their action has remained largely unknown. In this paper we have demonstrated that gold(I) drugs selectively activate the DNA binding of a heterodimer consisting of the basic-leucine zipper transcription factors Nrf2 and small Maf. Once bound to its recognition DNA sequence termed antioxidant-responsive element or Maf-recognition element, Nrf2/small Maf induces a set of antioxidative stress genes, including heme oxygenase-1 and gamma-glutamylcysteine synthetase, whose products have been demonstrated to contribute to the scavenging of reactive oxygen species and to exhibit anti-inflammatory effects. Our findings suggest that stimulation of antioxidative stress response through activation of Nrf2/small Maf may be a pharmacologically important part of the actions of gold(I) drugs for the treatment of rheumatoid arthritis. Alternatively, activation of Nrf2/small Maf may be a protective response of cells against toxic effects of the drugs.
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Affiliation(s)
- K Kataoka
- Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8503 Yokohama, Japan.
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Portis T, Harding JC, Ratner L. The contribution of NF-kappa B activity to spontaneous proliferation and resistance to apoptosis in human T-cell leukemia virus type 1 Tax-induced tumors. Blood 2001; 98:1200-8. [PMID: 11493471 DOI: 10.1182/blood.v98.4.1200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Human T-cell leukemia virus type I is the etiologic agent of adult T-cell leukemia/lymphoma. The Tax protein of this virus is thought to contribute to cellular transformation and tumor development. In this report, we have used a Tax transgenic mouse model of tumorigenesis to study the contribution of nuclear factor (NF)-kappa B activity to spontaneous tumor cell proliferation and resistance to apoptosis. We have demonstrated elevated expression levels of NF-kappa B--inducible cytokines, including interleukin (IL)-6, IL-10, IL-15, and interferon (IFN)-gamma, in freshly isolated primary tumors from Tax transgenic mice. Inhibitors of NF-kappa B activity, sodium salicylate and cyclopentenone prostaglandins (prostaglandin A(1) and 15-deoxy-Delta(12,14)-prostaglandin J(2)), blocked spontaneous proliferation of Tax transgenic mouse spleen cells. In addition, Tax-induced tumor cells, which are resistant to irradiation-induced apoptosis, became sensitive to apoptosis in the presence of sodium salicylate and prostaglandins. These results strongly suggest that Tax-mediated induction of NF-kappa B activity contributes to tumorigenesis in vivo. (Blood. 2001;98:1200-1208)
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Affiliation(s)
- T Portis
- Department of Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
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Abstract
The human T cell leukemia virus-1 (HTLV-1) is a retrovirus that causes adult T cell leukemia (ATL) and neurological disorder, the tropical spastic paraparesis (HAM/TSP). The pathogenesis apparently results from the pleiotropic function of Tax protein, which is a key regulator of viral replication. Tax exerts (a) trans-activation and -repression of transcription of different sets of cellular genes through binding to groups of transcription factors and coactivators, (b) dysregulation of cell cycle through binding to inhibitors of CDK4/6, and (c) inhibition of some tumor suppressor proteins. These effects on a wide variety of cellular targets seem to cooperate in promoting cell proliferation. This is an effective viral strategy to amplify its proviral genome through replication of infected cells; ultimately it results in cell transformation and leukemogenesis.
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Affiliation(s)
- M Yoshida
- Banyu Tsukuba Research Institute, Tsukuba, Ibaraki 300-2611, Japan.
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44
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Nishiya N, Tachibana K, Shibanuma M, Mashimo JI, Nose K. Hic-5-reduced cell spreading on fibronectin: competitive effects between paxillin and Hic-5 through interaction with focal adhesion kinase. Mol Cell Biol 2001; 21:5332-45. [PMID: 11463817 PMCID: PMC87257 DOI: 10.1128/mcb.21.16.5332-5345.2001] [Citation(s) in RCA: 83] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hic-5 is a paxillin homologue that is localized to focal adhesion complexes. Hic-5 and paxillin share structural homology and interacting factors such as focal adhesion kinase (FAK), Pyk2/CAKbeta/RAFTK, and PTP-PEST. Here, we showed that Hic-5 inhibits integrin-mediated cell spreading on fibronectin in a competitive manner with paxillin in NIH 3T3 cells. The overexpression of Hic-5 sequestered FAK from paxillin, reduced tyrosine phosphorylation of paxillin and FAK, and prevented paxillin-Crk complex formation. In addition, Hic-5-mediated inhibition of spreading was not observed in mouse embryo fibroblasts (MEFs) derived from FAK(-/-) mice. The activity of c-Src following fibronectin stimulation was decreased by about 30% in Hic-5-expressing cells, and the effect of Hic-5 was restored by the overexpression of FAK and the constitutively active forms of Rho-family GTPases, Rac1 V12 and Cdc42 V12, but not RhoA V14. These observations suggested that Hic-5 inhibits cell spreading through competition with paxillin for FAK and subsequent prevention of downstream signal transduction. Moreover, expression of antisense Hic-5 increased spreading in primary MEFs. These results suggested that the counterbalance of paxillin and Hic-5 expression may be a novel mechanism regulating integrin-mediated signal transduction.
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Affiliation(s)
- N Nishiya
- Department of Microbiology, Showa University School of Pharmaceutical Sciences, Hatanodai, Tokyo, Japan
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45
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Huo TI, Wang XW, Forgues M, Wu CG, Spillare EA, Giannini C, Brechot C, Harris CC. Hepatitis B virus X mutants derived from human hepatocellular carcinoma retain the ability to abrogate p53-induced apoptosis. Oncogene 2001; 20:3620-8. [PMID: 11439325 DOI: 10.1038/sj.onc.1204495] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2000] [Revised: 03/21/2001] [Accepted: 04/02/2001] [Indexed: 01/18/2023]
Abstract
Chronic hepatitis B virus (HBV) infection and the integration of its X gene (HBx) are closely associated with the development of hepatocellular carcinoma (HCC). The integrated HBx frequently is truncated or contains point mutations. Previous studies indicated that these HBx mutants have a diminished co-transactivational activity. We have compared the effects of wild-type (wt) HBx and its naturally occurring mutants derived from human HCCs on transcriptional co-transactivation, apoptosis and interactive effects with p53. We demonstrated that overexpression of mutant, but not wt HBx, is defective in transcriptional co-transactivation of the NF-kappaB-driven luciferase reporter. By using a microinjection technique, the HBx mutants were shown to have an attenuated pro-apoptotic activity. This deficiency may be attributed to multiple mutations in the co-transactivation domain of HBx, that leads to decreased stability of the translated product. However, wt or mutant HBx bind to p53 in vitro and retain their ability to block p53-mediated apoptosis in vivo, which has been implicated as its major tumor suppressor function. The abrogation of p53-mediated apoptosis by integrated HBx mutants may provide a selective clonal advantage for preneoplastic or neoplastic hepatocytes and contribute to hepatocellular carcinogenesis.
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Affiliation(s)
- T I Huo
- Laboratory of Human Carcinogenesis, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, MD 20892 USA
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46
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Jeang KT. Functional activities of the human T-cell leukemia virus type I Tax oncoprotein: cellular signaling through NF-kappa B. Cytokine Growth Factor Rev 2001; 12:207-17. [PMID: 11325603 DOI: 10.1016/s1359-6101(00)00028-9] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Human T-cell leukemia virus type I (HTLV-I) is the etiological agent for adult T-cell leukemia (ATL), as well as for tropical spastic paraparesis (TSP) and HTLV-I associate myelopathy (HAM). A biological understanding of the involvement of HTLV-I and in ATL has focused significantly on the workings of the virally-encoded 40 kDa phospho-oncoprotein, Tax. Tax is a transcriptional activator. Its ability to modulate the expression and function of many cellular genes has been reasoned to be a major contributory mechanism explaining HTLV-I-mediated transformation of cells. In activating cellular gene expression, Tax impinges upon several cellular signal-transduction pathways, including those for CREB/ATF and NF-kappa B. In this paper, we review aspects of Tax's transcriptional potential with particular focus on recent evidence linking Tax to IKK (I kappa B-kinase)-complex and MAP3Ks (mitogen-activated protein kinase kinase kinases).
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Affiliation(s)
- K T Jeang
- Laboratory of Molecular Microbiology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Room 306, Building 4, 4 Center Drive, MSC 0460, Bethesda, MD 20892-0460, USA.
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47
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Nawata H, Maeda Y, Sumimoto Y, Miyatake J, Kanamaru A. A mechanism of apoptosis induced by all-trans retinoic acid on adult T-cell leukemia cells: a possible involvement of the Tax/NF-kappaB signaling pathway. Leuk Res 2001; 25:323-31. [PMID: 11248329 DOI: 10.1016/s0145-2126(00)00126-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, five single clones were randomly established by limiting dilution method from each of the HTLV-I positive T cell lines - HUT 102 and ATL-2, and examined for the all-trans retinoic acid (ATRA) sensitivity, respectively. For each clone, we found a significant correlation between the reduction in 3[H]-thymidine incorporation and the reduction in CD25 expression (r=0.701, P<0.05) following treatment with 10(-5) M ATRA for 48 h. Agarose gel electrophoresis revealed DNA fragmentation of the cell lines treated with ATRA, indicative of apoptosis. These results suggested that the tax gene in the HTLV-I genome might be a key molecule involved in cell proliferation and CD25 expression. Thereafter, we transfected the tax gene in the expression vector (pCMV-Tax-neo) into the HTLV-I(-) T cell line Jurkat and examined the effects of ATRA on cell growth. The results showed that ATRA sensitivity was acquired by the Jurkat cells transfected with the tax gene expression vector, but not in those transfected with the control vector. We also observed NF-kappaB transcriptional activity on Jurkat cells transfected with the tax gene by CAT assay in the presence or absence of ATRA. NF-kappaB transcriptional activity was decreased significantly on Jurkat cells transfected with the tax gene after ATRA treatment. Taken together, these results indicate that ATRA may affect or block the Tax/NF-kappaB signaling pathway in ATL cells.
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Affiliation(s)
- H Nawata
- Third Department of Internal Medicine, Kinki University School of Medicine, 377-2, Ohno-Higashi, Osaka-Sayama, 589-8511, Osaka, Japan
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48
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Khorana AA, Rosenblatt JD, Young FM. Immunopathogenesis of HIV and HTLV-1 infection: mechanisms for lymphomagenesis. Cancer Treat Res 2001; 104:19-74. [PMID: 11191127 DOI: 10.1007/978-1-4615-1601-9_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/16/2023]
Affiliation(s)
- A A Khorana
- Cancer Center and Hematology-Oncology Unit, University of Rochester Medical Center, Rochester, New York, USA
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49
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Arima N, Tei C. HTLV-I Tax related dysfunction of cell cycle regulators and oncogenesis of adult T cell leukemia. Leuk Lymphoma 2001; 40:267-78. [PMID: 11426548 DOI: 10.3109/10428190109057925] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
HTLV-I is causually related to the oncogenesis of adult T cell leukemia (ATL). However, the precise mechanism of HTLV-I oncogenesis is unclear. HTLV-I Tax protein functions as an activator of various cellular genes, including IL-2, IL-2 receptor-alpha, and c-fos through the activation of nuclear transfer factors such as NF-kappaB and SRF, and also potently activates trascription of viral genes through CREB/ATF sites in the viral LTR. However, Tax activation of HTLV-I infected T cells through the above pathways induces polyclonal proliferation of the cells in vitro; Tax however may function only transiently in the immediate post-infection period following infection in vivo. The long latent period of 60 years from infection to onset of disease suggests other mechanisms for ATL oncogenesis. Recent studies suggest that the malignant transformation of ATL is a multi-hit phenomena, suggesting that discrete genetic events are responsible for ATL oncogenesis. These genetic events could be responsible for the different stages of ATL: smoldering, chronic, lymphoma, and acute type, p16 and p53 genes are important negative regulators of the cell cycle and are often found to be mutated in neoplasms. Recent studies including ours demonstrated a high frequency of alteration of these two genes in primary ATL cells. Furthermore, alteration of the two genes is associated with acute but not chronic type ATL. In addition, p16 gene alteration is linked to the growth rate of ATL cells, suggesting that the alteration of these cell cycle regulatory genes may be related to progression from smoldering or chronic to acute or lymphoma type ATL. Tax may be involved in mutagenesis of these genes through suppression of DNA-beta polymerase gene expression during the process from latent period to acute/lymphoma type. Once transformation occurs, activation of the pathway between Tax and the three nuclear transfer factors, NF-kappaB, SRF, and CREB/ATF, contributes to establish the aggressive manifestations of acute/lymphoma type ATL cells.
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Affiliation(s)
- N Arima
- First Department Internal Medicine, Faculty of Medicine, Kagoshima University, Japan.
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50
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Inoue T, Kwon AH, Oda M, Kaibori M, Kamiyama Y, Nishizawa M, Ito S, Okumura T. Hypoxia and heat inhibit inducible nitric oxide synthase gene expression by different mechanisms in rat hepatocytes. Hepatology 2000; 32:1037-44. [PMID: 11050054 DOI: 10.1053/jhep.2000.18715] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Ischemia/reperfusion contributes to the hepatic injury in resection and transplantation of the liver. However, the precise mechanisms involved in hypoxia stress remain to be clarified. Pro-inflammatory cytokines including interleukin 1beta (IL-1beta) induce a gene expression of inducible nitric oxide synthase (iNOS) and produce nitric oxide, which exerts either a cytoprotective or toxic effect. In this report, we found that hypoxia and heat markedly inhibited the induction of nitric oxide production stimulated by IL-1beta in rat cultured hepatocytes. Both treatments also abolished the induction of iNOS protein and mRNA. However, hypoxia could not prevent either degradation of an inhibitory protein (IkappaBalpha) of nuclear factor-kappaB (NF-kappaB) or translocation of NF-kappaB to the nucleus, whereas heat inhibited both of the IkappaBalpha degradation and NF-kappaB translocation. Transfection experiments with iNOS promoter construct revealed that hypoxia as well as heat significantly inhibited the transactivation of iNOS gene. Further, a hypoxia-response element located in the promoter was not involved in the inhibition of iNOS induction by hypoxia. These results indicate that hypoxia and heat suppress iNOS gene induction at the transcriptional level through different mechanisms. Reduction of nitric oxide production under hypoxic conditions may be implicated in the cellular damage or protection during hepatic ischemia/reperfusion.
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Affiliation(s)
- T Inoue
- First Department of Surgery, Kansai Medical University, Moriguchi, Osaka, Japan
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