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Hussain M, Lu Y, Tariq M, Jiang H, Shu Y, Luo S, Zhu Q, Zhang J, Liu J. A small-molecule Skp1 inhibitor elicits cell death by p53-dependent mechanism. iScience 2022; 25:104591. [PMID: 35789855 PMCID: PMC9249674 DOI: 10.1016/j.isci.2022.104591] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 04/21/2022] [Accepted: 06/08/2022] [Indexed: 11/28/2022] Open
Abstract
Skp1 overexpression promotes tumor growth, whereas reduced Skp1 activity is also linked with genomic instability and neoplastic transformation. This highlights the need to gain better understanding of Skp1 biology in cancer settings. To this context, potent and cellularly active small-molecule Skp1 inhibitors may be of great value. Using a hypothesis-driven, structure-guided approach, we herein identify Z0933M as a potent Skp1 inhibitor with KD ∼0.054 μM. Z0933M occupies a hydrophobic hotspot (P1) – encompassing an aromatic cage of two phenylalanines (F101 and F139) – alongside C-terminal extension of Skp1 and, thus, hampers its ability to interact with F-box proteins, a prerequisite step to constitute intact and active SCF E3 ligase(s) complexes. In cellulo, Z0933M disrupted SCF E3 ligase(s) functioning, recapitulated previously reported effects of Skp1-reduced activity, and elicited cell death by a p53-dependent mechanism. We propose Z0933M as valuable tool for future efforts toward probing Skp1 cancer biology, with implications for cancer therapy. Z0933M manifests strong binding with Skp1 and inhibits Skp1-F-box PPIs Z0933M interacts with a P1 hotspot alongside C-terminal extension of Skp1 Z0933M alters SCF E3 ligase functioning, leading to substrate accumulation/modulation Z0933M causes cell-cycle arrest, and elicits cell death by p53-dependent mechanism
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Affiliation(s)
- Muzammal Hussain
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Guangdong Provincial Key Laboratory of Biocomputing, Institute of Chemical Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Yongzhi Lu
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China
| | - Muqddas Tariq
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China
| | - Hao Jiang
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
| | - Yahai Shu
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
| | - Shuang Luo
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China
| | - Qiang Zhu
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- Bioland Laboratory (Guangzhou Regenerative Medicine and Health Guangdong Laboratory), Guangzhou 510005, China
| | - Jiancun Zhang
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Guangdong Provincial Key Laboratory of Biocomputing, Institute of Chemical Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Jinsong Liu
- State Key Laboratory of Respiratory Disease, Center for Chemical Biology and Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, 190 Kaiyuan Avenue, Science Park, Guangzhou 510530, China
- Guangdong Provincial Key Laboratory of Biocomputing, Institute of Chemical Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
- China-New Zealand Joint Laboratory on Biomedicine and Health, Guangzhou 510530, China
- Guangdong-Hong Kong-Macao Joint Laboratory of Respiratory Infectious Diseases, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
- Corresponding author
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Wu CJ, Lu CH, Chen LC, Nguyen DT, Huang YS, Lin HH, Lin CY, Kuo ML. CD4 down regulation and raft dissociation by the non-depleting YTS177 antibody hinder murine T helper cell activities. Biochem Biophys Res Commun 2016; 473:973-979. [PMID: 27045081 DOI: 10.1016/j.bbrc.2016.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 04/01/2016] [Indexed: 11/28/2022]
Abstract
Non-depleting YTS177 anti-CD4 monoclonal antibody (MoAb) has been reported to lead to antigen-specific immunotolerance in allograft transplantation and autoimmune diabetes, as well as possibly to inhibition of allergic inflammation in mice. However, the molecular mechanisms underlying hyporesponsive T cell responses induced by YTS177 MoAb remain elusive. Herein, we demonstrate that the YTS177 MoAb increases the levels of anergy factors p27(kip1) and Cbl-b, inhibits IL-2 production, and impairs calcium mobilization in activated T cells in vitro. YTS177 MoAb suppresses OVA-driven proliferation of DO11.10 CD4(+) T cells in vivo as well. Mechanistically, YTS177 MoAb induces tolerance by causing CD4 down-regulation through clathrin-dependent and raft dissociation. The results obtained in this study lead us to propose novel protective or curative approaches to CD4 T cell-mediated diseases.
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Affiliation(s)
- Cheng-Jang Wu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Chun-Hao Lu
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Li-Chen Chen
- Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
| | - Duc T Nguyen
- Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Yi-Shu Huang
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan
| | - Hsi-Hsien Lin
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Chang Gung Immunology Consortium, Chang Gung Memorial Hospital and Chang Gung University, Tao-Yuan, Taiwan; Department of Anatomic Pathology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
| | - Chun-Yen Lin
- Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Chang Gung Immunology Consortium, Chang Gung Memorial Hospital and Chang Gung University, Tao-Yuan, Taiwan; Department of Hepatogastroenterology, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan
| | - Ming-Ling Kuo
- Department of Microbiology and Immunology, Graduate Institute of Biomedical Sciences, College of Medicine, Chang Gung University, Tao-Yuan, Taiwan; Division of Allergy, Asthma, and Rheumatology, Department of Pediatrics, Chang Gung Memorial Hospital, Tao-Yuan, Taiwan; Chang Gung Immunology Consortium, Chang Gung Memorial Hospital and Chang Gung University, Tao-Yuan, Taiwan.
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3
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SEA antagonizes the imatinib-meditated inhibitory effects on T cell activation via the TCR signaling pathway. BIOMED RESEARCH INTERNATIONAL 2014; 2014:682010. [PMID: 24524084 PMCID: PMC3909973 DOI: 10.1155/2014/682010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 11/26/2013] [Accepted: 12/10/2013] [Indexed: 01/28/2023]
Abstract
The BCR-ABL kinase inhibitor imatinib is highly effective in the treatment of chronic myeloid leukemia (CML). However, long-term imatinib treatment induces immunosuppression, which is mainly due to T cell dysfunction. Imatinib can reduce TCR-triggered T cell activation by inhibiting the phosphorylation of tyrosine kinases such as Lck, ZAP70, LAT, and PLCγ1 early in the TCR signaling pathway. The purpose of this study was to investigate whether the superantigen SEA, a potent T cell stimulator, can block the immunosuppressive effects of imatinib on T cells. Our data show that the exposure of primary human T cells and Jurkat cells to SEA for 24 h leads to the upregulation of the Lck and ZAP70 proteins in a dose-dependent manner. T cells treated with SEA prior to TCR binding had increased the tyrosine phosphorylation of Lck, ZAP70, and PLCγ1. Pretreatment with SEA prevents the inhibitory effects of imatinib on TCR signaling, which leads to T cell proliferation and IL-2 production. It is conceivable that SEA antagonizes the imatinib-mediated inhibition of T cell activation and proliferation through the TCR signaling pathway.
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Cornwell WD, Rogers TJ. Uncoupling of T cell receptor zeta chain function during the induction of anergy by the superantigen, staphylococcal enterotoxin A. Toxins (Basel) 2010; 2:1704-17. [PMID: 22069657 PMCID: PMC3153262 DOI: 10.3390/toxins2071704] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 06/17/2010] [Accepted: 06/28/2010] [Indexed: 11/16/2022] Open
Abstract
Staphylococcus aureus enterotoxins have immunomodulatory properties. In this study, we show that Staphylococcal enterotoxin A (SEA) induces a strong proliferative response in a murine T cell clone independent of MHC class II bearing cells. SEA stimulation also induces a state of hypo-responsiveness (anergy). We characterized the components of the T cell receptor (TCR) during induction of anergy by SEA. Most interestingly, TCR zeta chain phosphorylation was absent under SEA anergizing conditions, which suggests an uncoupling of zeta chain function. We characterize here a model system for studying anergy in the absence of confounding costimulatory signals.
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Affiliation(s)
- William D Cornwell
- FELS Institute, Temple University School of Medicine, 3307 North Broad Street, Philadelphia, PA 19140, USA.
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Beyer M, Karbach J, Mallmann MR, Zander T, Eggle D, Classen S, Debey-Pascher S, Famulok M, Jäger E, Schultze JL. Cancer vaccine enhanced, non-tumor-reactive CD8(+) T cells exhibit a distinct molecular program associated with "division arrest anergy". Cancer Res 2009; 69:4346-54. [PMID: 19435912 DOI: 10.1158/0008-5472.can-08-3796] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Immune-mediated tumor rejection relies on fully functional T-cell responses and neutralization of an adverse tumor microenvironment. In clinical trials, we detected peptide-specific but non-tumor-reactive and therefore not fully functional CD8(+) T cells post-vaccination against tumor antigens. Understanding the molecular mechanisms behind nontumor reactivity will be a prerequisite to overcome this CD8(+) T-cell deviation. We report that these non-tumor-reactive CD8(+) T cells are characterized by a molecular program associated with hallmarks of "division arrest anergy." Non-tumor-reactive CD8(+) T cells are characterized by coexpression of CD7, CD25, and CD69 as well as elevated levels of lck(p505) and p27(kip1). In vivo quantification revealed high prevalence of non-tumor-reactive CD8(+) T cells with increased levels during cancer vaccination. Furthermore, their presence was associated with a trend toward shorter survival. Dynamics and frequencies of non-target-reactive CD8(+) T cells need to be further addressed in context of therapeutic vaccine development in cancer, chronic infections, and autoimmune diseases.
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Affiliation(s)
- Marc Beyer
- Life and Medical Sciences Bonn, Laboratories for Genomics and Immunoregulation, University of Bonn, Bonn, Germany
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Dexamethasone augments CXCR4-mediated signaling in resting human T cells via the activation of the Src kinase Lck. Blood 2008; 113:575-84. [PMID: 18840710 DOI: 10.1182/blood-2008-04-151803] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Dexamethasone (DM) is a synthetic member of the glucocorticoid (GC) class of hormones that possesses anti-inflammatory and immunosuppressant activity and is commonly used to treat chronic inflammatory disorders, severe allergies, and other disease states. Although GCs are known to mediate well-defined transcriptional effects via GC receptors (GCR), there is increasing evidence that GCs also initiate rapid nongenomic signaling events in a variety of cell types. Here, we report that DM induces the phosphorylation of Lck and the activation of other downstream mediators, including p59Fyn, Zap70, Rac1, and Vav in resting but not activated human T cells. DM treatment also augments CXCL12-mediated signaling in resting T cells through its cell surface receptor, CXCR4 resulting in the enhanced actin polymerization, Rac activation, and cell migration on ligand exposure. Lck was found to be a critical intermediate in these DM-induced signaling activities. Moreover, DM-mediated Lck phosphorylation in T cells was dependent on the presence of both the GCR and the CD45 molecule. Overall, these results elucidate additional nongenomic effects of DM and the GCR on resting human T cells, inducing Lck and downstream kinase activation and augmenting chemokine signaling and function.
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Horejsí V. Lipid rafts and their roles in T-cell activation. Microbes Infect 2005; 7:310-6. [PMID: 15715974 DOI: 10.1016/j.micinf.2004.12.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 09/01/2004] [Indexed: 10/25/2022]
Abstract
Lipid rafts are defined as detergent-resistant membrane microdomains of specific lipid and protein composition. They are involved in many aspects of cell biology, including T-cell activation and immunoreceptor signaling. This review discusses current controversies around lipid rafts and summarizes recent developments in the area.
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Affiliation(s)
- Václav Horejsí
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4, Czech Republic.
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Criado G, Madrenas J. Superantigen stimulation reveals the contribution of Lck to negative regulation of T cell activation. THE JOURNAL OF IMMUNOLOGY 2004; 172:222-30. [PMID: 14688329 DOI: 10.4049/jimmunol.172.1.222] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The conventional paradigm of T cell activation through the TCR states that Lck plays a critical activating role in this signaling process. However, the T cell response to bacterial superantigens does not require Lck. In this study we report that not only is Lck dispensable for T cell activation by superantigens, but it actively inhibits this signaling pathway. Disruption of Lck function, either by repression of Lck gene expression or by selective pharmacologic inhibitors of Lck, led to increased IL-2 production in response to superantigen stimulation. This negative regulatory effect of Lck on superantigen-induced T cell responses required the kinase activity of Lck and correlated with early TCR signaling, but was independent of immunological synapse formation and TCR internalization. Our data demonstrate that the multistage role of Lck in T cell signaling includes the activation of a negative regulatory pathway of T cell activation.
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Affiliation(s)
- Gabriel Criado
- FOCIS Center for Clinical Immunology and Immunotherapeutics, Robarts Research Institute, 100 Perth Drive, London, Ontario, Canada N6A 5K8
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Imanishi K, Kato H, Fujii H, Uchiyama T. Maturation of adult peripheral blood CD38(+)CD4(+) T cells demonstrated by cytokine production in response to a superantigen, TSST-1. Cell Immunol 2003; 222:89-96. [PMID: 12826078 DOI: 10.1016/s0008-8749(03)00111-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This study looks at immunoincompetent CD4(+) T cells in adult peripheral blood (APB) using cytokine production in response to a superantigen as a measure of function. We compared the function of APB CD38(+)CD4(+) and CD38(-/low)CD4(+) T cells to that of cord blood (CB) CD4(+) T cells. APB CD4(+) T cell blasts produce substantial amounts of IL-2 in response to TSST-1 restimulation, while CB CD4(+) T cell blasts produce less. APB CD38(+)CD4(+) T cells produce low levels of IL-4 and IFN-gamma in response to TSST-1, even after activation, while APB CD38(-/low)CD4(+) T cells retain their ability to produce high levels of these cytokines despite high CD38 expression. These results suggest that the developmental stage of APB CD38(+)CD4(+) T cells lies between that of CB CD4(+) T cells and APB CD38(-/low)CD4(+) T cells and that APB CD38(+)CD45RO(-)CD4(+) T cells gradually cease to express CD38 as they acquire full function. We reconsider CD4(+) cell maturation and response to TSST-1 and discuss the implications of T cell maturity on infectious diseases.
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Affiliation(s)
- Ken'ichi Imanishi
- Department of Microbiology and Immunology, Tokyo Women's Medical University School of Medicine, Tokyo, Japan.
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Abstract
Detergent-resistant membrane microdomains enriched in sphingolipids, cholesterol and glycosylphosphatidylinositol-anchored proteins play essential roles in T cell receptor (TCR) signaling. These 'membrane rafts' accumulate several cytoplasmic lipid-modified molecules, including Src-family kinases, coreceptors CD4 and CD8 and transmembrane adapters LAT and PAG/Cbp, essential for either initiation or amplification of the signaling process, while most other abundant transmembrane proteins are excluded from these structures. TCRs in various T cell subpopulations may differ in their use of membrane rafts. Membrane rafts also seem to be involved in many other aspects of T cell biology, such as functioning of cytokine and chemokine receptors, adhesion molecules, antigen presentation, establishing cell polarity or interaction with important pathogens. Although the concept of membrane rafts explains several diverse biological phenomena, many basic issues, such as composition, size and heterogeneity, under native conditions, as well as the dynamics of their interactions with TCRs and other immunoreceptors, remain unclear, partially because of technical problems.
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Affiliation(s)
- Václav Horejsí
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Praha, Czech Republic.
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Chen L, Koyanagi M, Fukada K, Imanishi K, Yagi J, Kato H, Miyoshi-Akiyama T, Zhang R, Miwa K, Uchiyama T. Continuous exposure of mice to superantigenic toxins induces a high-level protracted expansion and an immunological memory in the toxin-reactive CD4+ T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:3817-24. [PMID: 11937534 DOI: 10.4049/jimmunol.168.8.3817] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We analyzed the responses of several T cell fractions reactive with superantigenic toxins (SAGTs), staphylococcal enterotoxin A (SEA), or Yersinia pseudotuberculosis-derived mitogen (YPM) in mice implanted with mini-osmotic pumps filled with SEA or YPM. In mice implanted with the SEA pump, SEA-reactive Vbeta3(+)CD4(+) T cells exhibited a high-level protracted expansion for 30 days, and SEA-reactive Vbeta11(+)CD4(+) T cells exhibited a low-level protracted expansion. SEA-reactive CD8(+) counterparts exhibited only a transient expansion. A similar difference in T cell expansion was also observed in YPM-reactive T cell fractions in mice implanted with the YPM pump. Vbeta3(+)CD4(+) and Vbeta11(+)CD4(+) T cells from mice implanted with the SEA pump exhibited cell divisions upon in vitro restimulation with SEA and expressed surface phenotypes as memory T cells. CD4(+) T cells from mice implanted with the SEA pump exhibited high IL-4 production upon in vitro restimulation with SEA, which was due to the enhanced capacity of the SEA-reactive CD4(+) T cells to produce IL-4. The findings in the present study indicate that, in mice implanted with a specific SAGT, the level of expansion of the SAGT-reactive CD4(+) T cell fractions varies widely depending on the TCR Vbeta elements expressed and that the reactive CD4(+) T cells acquire a capacity to raise a memory response. CD8(+) T cells are low responders to SAGTs.
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Affiliation(s)
- Luqiu Chen
- Department of Microbiology and Immunology, School of Medicine, Tokyo Women's Medical University, Ohtsu, Japan
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Ishii T, Ohnuma K, Murakami A, Takasawa N, Kobayashi S, Dang NH, Schlossman SF, Morimoto C. CD26-mediated signaling for T cell activation occurs in lipid rafts through its association with CD45RO. Proc Natl Acad Sci U S A 2001; 98:12138-43. [PMID: 11593028 PMCID: PMC59781 DOI: 10.1073/pnas.211439098] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/20/2001] [Indexed: 11/18/2022] Open
Abstract
CD26 is a T cell activation antigen that contains dipeptidyl peptidase IV activity and is known to bind adenosine deaminase. The mechanism by which CD26 costimulation potentiates T cell receptor-mediated T cell activation, leading to subsequent exertion of T cell effector function, is still not clearly defined. In this article, we demonstrate that CD26 localizes into lipid rafts, and targeting of CD26 to rafts is necessary for signaling events through CD26. Importantly, aggregation of CD26 by anti-CD26 mAb crosslinking also causes coaggregation of CD45 into rafts. Moreover, we show that CD26 directly binds to the cytoplasmic domain of CD45. Our results therefore indicate a mechanism whereby CD26 engagement promotes aggregation of lipid rafts and facilitates colocalization of CD45 to T cell receptor signaling molecules p56(Lck), ZAP-70, and TCRzeta, thereby enhancing protein tyrosine phosphorylation of various signaling molecules and subsequent interleukin-2 production.
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Affiliation(s)
- T Ishii
- Department of Clinical Immunology, Advanced Clinical Research Center, Institute of Medical Science, University of Tokyo, 4-6-1, Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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