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Dyshlovoy SA, Rast S, Hauschild J, Otte K, Alsdorf WH, Madanchi R, Kalinin VI, Silchenko AS, Avilov SA, Dierlamm J, Honecker F, Stonik VA, Bokemeyer C, von Amsberg G. Frondoside A induces AIF-associated caspase-independent apoptosis in Burkitt lymphoma cells. Leuk Lymphoma 2017; 58:2905-2915. [PMID: 28508718 DOI: 10.1080/10428194.2017.1317091] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
For patients with refractory or relapsed Burkitt lymphoma (BL), no standard therapy is available for second-line treatment to date. Nonfunctional caspases-dependent apoptosis pathways, inactivating p53 mutations and pro-survival autophagy prevent activity of conventional chemotherapy. Thus, new drugs bypassing these mechanisms of resistance are required. Here, we investigated the efficacy of the marine natural compound frondoside A (FrA) in eight BL cell lines. FrA revealed cytotoxic effects in all cell lines tested including the multiresistant CA46 cells. Remarkably, FrA induced caspases- and p53-independent apoptosis, which was characterized by decreased expression of antiapoptotic survivin and Bcl-2, mitochondria targeting (release of cytochrome C, HtrA2/Omi and the apoptosis-inducing factor (AIF), and altered production of ROS) and translocation of AIF to the nuclei. In addition, signs of inhibition of pro-survival autophagy were observed. Thus, FrA is a promising candidate for the treatment of refractory or relapsed BL revealing resistances to standard therapies.
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Affiliation(s)
- Sergey A Dyshlovoy
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.,b Laboratory of Marine Natural Products Chemistry , G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences , Vladivostok , Russian Federation.,c School of Natural Sciences , Far Eastern Federal University , Vladivostok , Russian Federation
| | - Stefanie Rast
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Jessica Hauschild
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Katharina Otte
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Winfried H Alsdorf
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Ramin Madanchi
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Vladimir I Kalinin
- b Laboratory of Marine Natural Products Chemistry , G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences , Vladivostok , Russian Federation
| | - Alexandra S Silchenko
- b Laboratory of Marine Natural Products Chemistry , G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences , Vladivostok , Russian Federation
| | - Sergey A Avilov
- b Laboratory of Marine Natural Products Chemistry , G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences , Vladivostok , Russian Federation
| | - Judith Dierlamm
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Friedemann Honecker
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany.,d Tumor and Breast Center ZeTuP , St. Gallen , Switzerland
| | - Valentin A Stonik
- b Laboratory of Marine Natural Products Chemistry , G.B. Elyakov Pacific Institute of Bioorganic Chemistry, Far-East Branch, Russian Academy of Sciences , Vladivostok , Russian Federation
| | - Carsten Bokemeyer
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
| | - Gunhild von Amsberg
- a Department of Oncology, Hematology and Bone Marrow Transplantation with Section Pneumology , Hubertus Wald-Tumorzentrum, University Medical Center Hamburg-Eppendorf , Hamburg , Germany
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Xu J, Zhao J, Li Y, Zou Y, Lu B, Chen Y, Ma Y, Xu H. Evaluation of differentially expressed immune-related genes in intestine of Pelodiscus sinensis after intragastric challenge with lipopolysaccharide based on transcriptome analysis. FISH & SHELLFISH IMMUNOLOGY 2016; 56:417-426. [PMID: 27475104 DOI: 10.1016/j.fsi.2016.07.032] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 07/01/2016] [Accepted: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Pelodiscus sinensis is the most common turtle species that has been raised in East and Southeast Asia. However, there are still limited studies about the immune defense mechanisms in its small intestine until now. In the present research, histological analysis and transcriptome analysis was performed on the small intestine of P. sinensis after intragastric challenge with LPS to explore its mechanisms of immune responses to pathogens. The result showed the number of intraepithelial lymphocytes (IELs) and goblet cells (GCs) in its intestine increased significantly at 48 h post-challenge with LPS by intragastrical route, indicating clearly the intestinal immune response was induced. Compared with the control, a total of 748 differentially expressed genes (DEGs) were identified, including 361 up-regulated genes and 387 down-regulated genes. Based on the Gene Ontology (GO) annotation and the Kyoto Encyclopedia of Genes and Genomes (KEGG), 48 immune-related DEGs were identified, which were classified into 82 GO terms and 14 pathways. Finally, 18 DEGs, which were randomly selected, were confirmed by quantitative real-time PCR (qRT-PCR). Our results provide valuable information for further analysis of the immune defense mechanisms against pathogens in the small intestine of P. sinensis.
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Affiliation(s)
- Jiehao Xu
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Jing Zhao
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Yiqun Li
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Yiyi Zou
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Binjie Lu
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Yuyin Chen
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Youzhi Ma
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China
| | - Haisheng Xu
- College of Animal Sciences, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, Zhejiang Province, China.
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Abstract
The predominant function of the tumor suppressor p53 is transcriptional regulation. It is generally accepted that p53-dependent transcriptional activation occurs by binding to a specific recognition site in promoters of target genes. Additionally, several models for p53-dependent transcriptional repression have been postulated. Here, we evaluate these models based on a computational meta-analysis of genome-wide data. Surprisingly, several major models of p53-dependent gene regulation are implausible. Meta-analysis of large-scale data is unable to confirm reports on directly repressed p53 target genes and falsifies models of direct repression. This notion is supported by experimental re-analysis of representative genes reported as directly repressed by p53. Therefore, p53 is not a direct repressor of transcription, but solely activates its target genes. Moreover, models based on interference of p53 with activating transcription factors as well as models based on the function of ncRNAs are also not supported by the meta-analysis. As an alternative to models of direct repression, the meta-analysis leads to the conclusion that p53 represses transcription indirectly by activation of the p53-p21-DREAM/RB pathway.
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Key Words
- CDE, cell cycle-dependent element
- CDKN1A
- CHR, cell cycle genes homology region
- ChIP, chromatin immunoprecipitation
- DREAM complex
- DREAM, DP, RB-like, E2F4, and MuvB complex
- E2F/RB complex
- HPV, human papilloma virus
- NF-Y, Nuclear factor Y
- cdk, cyclin-dependent kinase
- genome-wide meta-analysis
- p53
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Affiliation(s)
- Martin Fischer
- a Molecular Oncology; Medical School ; University of Leipzig ; Leipzig , Germany
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Madapura HS, Salamon D, Wiman KG, Lain S, Klein G, Klein E, Nagy N. p53 contributes to T cell homeostasis through the induction of pro-apoptotic SAP. Cell Cycle 2012; 11:4563-9. [PMID: 23165210 DOI: 10.4161/cc.22810] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Lack of functional SAP protein, due to gene deletion or mutation, is the cause of X-linked lymphoproliferative disease (XLP), characterized by functionally impaired T and NK cells and a high risk of lymphoma development. We have demonstrated earlier that SAP has a pro-apoptotic function in T and B cells. Deficiency of this function might contribute to the pathogenesis of XLP. We have also shown that SAP is a target of p53 in B cell lines. In the present study, we show that activated primary T cells express p53, which induces SAP expression. p53 is functional as a transcription factor in activated T cells and induces the expression of p21, PUMA and MDM2. PARP cleavage in the late phase of activation indicates that T cells expressing high levels of SAP undergo apoptosis. Modifying p53 levels using Nutlin-3, which specifically dissociates the MDM2-p53 interaction, was sufficient to upregulate SAP expression, indicating that SAP is a target of p53 in T cells. We also demonstrated p53's role as a transcription factor for SAP in activated T cells by ChIP assays. Our result suggests that p53 contributes to T cell homeostasis through the induction of the pro-apoptotic SAP. A high level of SAP is necessary for the activation-induced cell death that is pivotal in termination of the T cell response.
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Affiliation(s)
- Harsha S Madapura
- Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden
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Nagy N, Klein E. Deficiency of the proapoptotic SAP function in X-linked lymphoproliferative disease aggravates Epstein-Barr virus (EBV) induced mononucleosis and promotes lymphoma development. Immunol Lett 2010; 130:13-8. [DOI: 10.1016/j.imlet.2010.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Nagy N, Klein G, Klein E. To the genesis of Burkitt lymphoma: Regulation of apoptosis by EBNA-1 and SAP may determine the fate of Ig-myc translocation carrying B lymphocytes. Semin Cancer Biol 2009; 19:407-10. [DOI: 10.1016/j.semcancer.2009.10.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Accepted: 10/15/2009] [Indexed: 01/23/2023]
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The proapoptotic function of SAP provides a clue to the clinical picture of X-linked lymphoproliferative disease. Proc Natl Acad Sci U S A 2009; 106:11966-71. [PMID: 19570996 DOI: 10.1073/pnas.0905691106] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Deletion or mutation of the SAP gene is associated with the X-linked lymphoproliferative disease (XLP) that is characterized by extreme sensitivity to Epstein-Barr virus (EBV). Primary infection of the affected individuals leads to serious, sometimes fatal infectious mononucleosis (IM) and proneness to lymphoma. Our present results revealed a proapoptotic function of SAP by which it contributes to the maintenance of T-cell homeostasis and to the elimination of potentially dangerous DNA-damaged cells. Therefore, the loss of this function could be responsible for the uncontrolled T-cell proliferation in fatal IM and for the generation of lymphomas. We show now the role of SAP in apoptosis in T and B lymphocyte-derived lines. Among the clones of T-ALL line, the ones with higher SAP levels succumbed more promptly to activation induced cell death (AICD). Importantly, introduction of SAP expression into lymphoblastoid cell lines (LCL) established from XLP patients led to elevated apoptotic response to DNA damage. Similar results were obtained in the osteosarcoma line, Saos-2. We have shown that the anti-apoptotic protein VCP (valosin-containing protein) binds to SAP, suggesting that it could be instrumental in the enhanced apoptotic response modulated by SAP.
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Ostrakhovitch EA, Wang Y, Li SSC. SAP binds to CD22 and regulates B cell inhibitory signaling and calcium flux. Cell Signal 2008; 21:540-50. [PMID: 19150402 DOI: 10.1016/j.cellsig.2008.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Revised: 12/10/2008] [Accepted: 12/15/2008] [Indexed: 01/25/2023]
Abstract
The signaling lymphocyte activation molecule (SLAM)-associated protein (SAP or SH2D1A) is an important regulator of immune function which, when mutated or deleted, causes the X-linked lymphoproliferative syndrome (XLP). Because B cell lymphoma is a major phenotype of XLP, it is important to understand the function of SAP in B cells. Here we report that SAP is expressed endogenously in mouse splenic B cells, is inducibly expressed in the human BJAB cells, and co-localizes and interacts with CD22. We also show that SAP binding to the inhibitory immunoreceptor CD22 regulates calcium mobilization in B cells. Moreover, forced expression of SAP leads to constitutive CD22 tyrosine phosphorylation and decreased Ca(2+) response in B cells. Biochemical analysis reveals that, in response to IgM cross-linking, the phosphorylation of Syk, Blnk, or PLCgamma2 and their interactions with one another were either diminished or completely abolished in SAP-expressing cells compared to cells that lack SAP. Collectively our work identifies a novel role for SAP in B cells and extends its function to inhibitory immunoreceptor signaling and calcium mobilization.
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Affiliation(s)
- Elena A Ostrakhovitch
- Department of Biochemistry and the Siebens-Drake Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada N6A 5C1.
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Abstract
The p53 protein plays a key role in securing the apoptotic response of chronic lymphocytic leukemia (CLL) cells to genotoxic agents. Transcriptional induction of proapoptotic proteins including Puma are thought to mediate p53-dependent apoptosis. In contrast, recent studies have identified a novel nontranscriptional mechanism, involving direct binding of p53 to antiapoptotic proteins including Bcl-2 at the mitochondrial surface. Here we show that the major fraction of p53 induced in CLL cells by chlorambucil, fludarabine, or nutlin 3a was stably associated with mitochondria, where it binds to Bcl-2. The Puma protein, which was constitutively expressed in a p53-independent manner, was modestly up-regulated following p53 induction. Pifithrin α, an inhibitor of p53-mediated transcription, blocked the up-regulation of Puma and also of p21CIP1. Surprisingly, pifithrin α dramatically augmented apoptosis induction by p53-elevating agents and also accelerated the proapoptotic conformation change of the Bax protein. These data suggest that direct interaction of p53 with mitochondrial antiapoptotic proteins including Bcl-2 is the major route for apoptosis induction in CLL cells and that p53's transcriptional targets include proteins that impede this nontranscriptional pathway. Therefore, strategies that block up-regulation of p53-mediated transcription may be of value in enhancing apoptosis induction of CLL cells by p53-elevating drugs.
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Chuang HC, Wang JM, Hsieh WC, Chang Y, Su IJ. Up-regulation of activating transcription factor-5 suppresses SAP expression to activate T cells in hemophagocytic syndrome associated with Epstein-Barr virus infection and immune disorders. THE AMERICAN JOURNAL OF PATHOLOGY 2008; 173:1397-405. [PMID: 18832568 DOI: 10.2353/ajpath.2008.080440] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hemophagocytic syndrome (HPS) is a fatal, pro-inflammatory cytokine disorder that is associated with viral infections and immune disorders. Previously, we demonstrated that Epstein-Barr virus latent membrane protein-1 (LMP-1) could down-regulate the SAP gene, enhancing Th1 cytokine secretion in T cells and leading to HPS. The exact mechanism of SAP gene regulation by LMP-1 remains to be clarified. In this study, using cDNA microarray analysis, we identified ATF5 as the candidate transcriptional repressor for SAP expression in LMP-1-expressing T cells. LMP-1 up-regulated ATF5 via TRAF2,5/NF-kappaB signals to suppress SAP gene expression. Reporter assays and electrophoretic mobility shift assays revealed that ATF5 bound differentially to two sites of the SAP promoter. In resting T cells, ATF5 bound predominantly to the high-affinity site in the -81 to -74 region while additionally binding to the low-affinity site at -305 to -296 in LMP-1-expressing T cells. Such binding subsequently disrupted the transcription of the SAP gene. At the same time, Th1 cytokine secretion was enhanced. This phenomenon was also observed in conditions such as ATF5 overexpression, phytohemagglutinin stimulation of primary T cells, and ligand engagement of T-cell lines. Therefore, the down-regulation of the SAP gene by ATF5 may represent a common mechanism for the pathogenesis of HPS that is associated with either Epstein-Barr virus infection or immune disorders with dysregulated T-cell activation.
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Affiliation(s)
- Huai-Chia Chuang
- Division of Clinical Research, National Health Research Institutes, Tainan, Taiwan
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Ostrakhovitch EA, Li SSC. The role of SLAM family receptors in immune cell signaling. Biochem Cell Biol 2007; 84:832-43. [PMID: 17215871 DOI: 10.1139/o06-191] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The signaling lymphocyte-activating molecule (SLAM) family immunoreceptors are expressed in a wide array of immune cells, including both T and B lymphocytes. By virtue of their ability to transduce tyrosine phosphorylation signals through the so-called ITSM (immunoreceptor tyrosine-based switch motif) sequences, they play an important part in regulating both innate and adaptive immune responses. The critical role of the SLAM immunoreceptors in mediating normal immune reactions was highlighted in recent findings that SAP, a SLAM-associated protein, modulates the activities of various immune cells through interactions with different members of the SLAM family expressed in these cells. Importantly, mutations or deletions of the sap gene in humans result in the X-linked lymphoproliferative syndrome. In this review, we summarize current knowledge and survey the latest developments in signal transduction events triggered by the activation of SLAM family receptors in different cell types.
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Affiliation(s)
- Elena A Ostrakhovitch
- Department of Biochemistry, Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON N6A 5C1, Canada
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Calpe S, Erdos E, Liao G, Wang N, Rietdijk S, Simarro M, Scholtz B, Mooney J, Lee CH, Shin MS, Rajnavölgyi E, Schatzle J, Morse HC, Terhorst C, Lanyi A. Identification and characterization of two related murine genes, Eat2a and Eat2b, encoding single SH2-domain adapters. Immunogenetics 2006; 58:15-25. [PMID: 16425036 DOI: 10.1007/s00251-005-0056-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Accepted: 09/20/2005] [Indexed: 12/28/2022]
Abstract
Human EAT-2 (SH2D1B) and SLAM-associated protein (SAP) (SH2D1A) are single SH2-domain adapters, which bind to specific tyrosine residues in the cytoplasmic tail of six signaling lymphocytic activation molecule (SLAM) (SLAMF1)-related receptors. Here we report that, unlike in humans, the mouse and rat Eat2 genes are duplicated with an identical genomic organization. The coding regions of the mouse Eat2a and Eat2b genes share 91% identity at the nucleotide level and 84% at the protein level; similarly, segments of introns are highly conserved. Whereas expression of mouse Eat2a mRNA was detected in multiple tissues, Eat2b was only detectable in mouse natural killer cells, CD8+ T cells, and ovaries, suggesting a very restricted tissue expression of the latter. Both the EAT-2A and EAT-2B coimmunoprecipitated with mouse SLAM in transfected cells and augmented tyrosine phosphorylation of the cytoplasmic tail of SLAM. Both EAT-2A and EAT-2B bind to the Src-like kinases Fyn, Hck, Lyn, Lck, and Fgr, as determined by a yeast two-hybrid assay. However, unlike SAP, the EAT-2 proteins bind to their kinase domains and not to the SH3 domain of these kinases. Taken together, the data suggest that both EAT-2A and EAT-2B are adapters that recruit Src kinases to SLAM family receptors using a mechanism that is distinct from that of SAP.
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MESH Headings
- Adaptor Proteins, Signal Transducing/genetics
- Adaptor Proteins, Signal Transducing/metabolism
- Amino Acid Sequence
- Animals
- Antigens, CD/analysis
- Cells, Cultured
- Chromosomes, Artificial, Bacterial
- Expressed Sequence Tags
- Glycoproteins/metabolism
- Immunoglobulins/metabolism
- Mice
- Mice, Congenic
- Mice, Inbred C57BL
- Molecular Sequence Data
- Phosphorylation
- Protein Binding/physiology
- Rats
- Receptors, Cell Surface
- Sequence Homology, Amino Acid
- Signal Transduction
- Signaling Lymphocytic Activation Molecule Family Member 1
- Transcription Factors/genetics
- Transcription Factors/metabolism
- Transfection
- src Homology Domains/genetics
- src-Family Kinases/metabolism
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Affiliation(s)
- Silvia Calpe
- Division of Immunology BIDMC, Harvard Medical School, 77 Ave. Louis Pasteur, Boston, MA 02115, USA.
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Chuang HC, Lay JD, Hsieh WC, Wang HC, Chang Y, Chuang SE, Su IJ. Epstein-Barr virus LMP1 inhibits the expression of SAP gene and upregulates Th1 cytokines in the pathogenesis of hemophagocytic syndrome. Blood 2005; 106:3090-6. [PMID: 16002423 DOI: 10.1182/blood-2005-04-1406] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The primary infection of Epstein-Barr virus (EBV) may result in fatal infectious mononucleosis or hemophagocytic syndrome (HPS) in 2 diseases; that is, X-linked lymphoproliferative disorder (XLP) and hemophagocytic lymphohistiocytosis (HLH). XLP is linked to mutations of the SAP/SH2D1A gene with dysregulated T-cell activation in response to EBV infection. Patients with sporadic HLH, however, usually have no mutation of the SAP/SH2D1A gene, and EBV latent membrane protein-1 (LMP1) can up-regulate Th1 cytokines in EBV-infected T cells. Since both diseases share common manifestations of HPS, it is important to clarify whether a cross-talk exists between signaling lymphocyte activation molecule (SLAM)-associated protein (SAP) and LMP1-mediated pathways to explain the common pathogenesis of HPS. In this study, no mutation of the SAP/SH2D1A gene at exon 2/3 was detected in 7 HLH cases. Interestingly, EBV LMP1 could transcriptionally inhibit the expression of SAP/SH2D1A and activate downstream molecules ERK and interferon-gamma (IFN-gamma). LMP1-mediated SAP/ERK/IFN-gamma signals appear to act via the TNF receptor-associated factor (TRAF)2,5/nuclear factor kappaB (NF-kappaB) pathway, since dominant-negative TRAF2/5 and NF-kappaB inhibitor could rescue SAP expression and downregulate IFN-gamma. Although HLH is genetically distinct from XLP, our data suggest that both diseases share a common signal pathway, through either the mutation or LMP1-mediated suppression of the SAP gene, leading to overt T-cell activation and enhanced Th1 cytokine secretion in response to EBV infection.
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Affiliation(s)
- Huai-Chia Chuang
- Division of Clinical Research, National Health Research Institutes, 12C, 138, Sheng-Li Rd, Tainan, Taiwan
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