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Borowicz P, Sundvold V, Chan H, Abrahamsen G, Kjelstrup H, Nyman TA, Spurkland A. Tyr 192 Regulates Lymphocyte-Specific Tyrosine Kinase Activity in T Cells. THE JOURNAL OF IMMUNOLOGY 2021; 207:1128-1137. [PMID: 34321230 DOI: 10.4049/jimmunol.2001105] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Accepted: 06/07/2021] [Indexed: 11/19/2022]
Abstract
TCR signaling critically depends on the tyrosine kinase Lck (lymphocyte-specific protein tyrosine kinase). Two phosphotyrosines, the activating pTyr394 and the inhibitory pTyr505, control Lck activity. Recently, pTyr192 in the Lck SH2 domain emerged as a third regulator. How pTyr192 may affect Lck function remains unclear. In this study, we explored the role of Lck Tyr192 using CRISPR/Cas9-targeted knock-in mutations in the human Jurkat T cell line. Our data reveal that both Lck pTyr394 and pTyr505 are controlled by Lck Tyr192 Lck with a nonphosphorylated SH2 domain (Lck Phe192) displayed hyperactivity, possibly by promoting Lck Tyr394 transphosphorylation. Lck Glu192 mimicking stable Lck pTyr192 was inhibited by Tyr505 hyperphosphorylation. To overcome this effect, we further mutated Tyr505 The resulting Lck Glu192/Phe505 displayed strongly increased amounts of pTyr394 both in resting and activated T cells. Our results suggest that a fundamental role of Lck pTyr192 may be to protect Lck pTyr394 and/or pTyr505 to maintain a pool of already active Lck in resting T cells. This provides an additional mechanism for fine-tuning of Lck as well as T cell activity.
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Affiliation(s)
- Paweł Borowicz
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
| | - Vibeke Sundvold
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
| | - Hanna Chan
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
| | - Greger Abrahamsen
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
| | - Hanna Kjelstrup
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
| | - Tuula A Nyman
- Department of Immunology, Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Anne Spurkland
- Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway; and
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2
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PD-1 suppresses TCR-CD8 cooperativity during T-cell antigen recognition. Nat Commun 2021; 12:2746. [PMID: 33980853 PMCID: PMC8115078 DOI: 10.1038/s41467-021-22965-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 04/09/2021] [Indexed: 12/31/2022] Open
Abstract
Despite the clinical success of blocking its interactions, how PD-1 inhibits T-cell activation is incompletely understood, as exemplified by its potency far exceeding what might be predicted from its affinity for PD-1 ligand-1 (PD-L1). This may be partially attributed to PD-1's targeting the proximal signaling of the T-cell receptor (TCR) and co-stimulatory receptor CD28 via activating Src homology region 2 domain-containing phosphatases (SHPs). Here, we report PD-1 signaling regulates the initial TCR antigen recognition manifested in a smaller spreading area, fewer molecular bonds formed, and shorter bond lifetime of T cell interaction with peptide-major histocompatibility complex (pMHC) in the presence than absence of PD-L1 in a manner dependent on SHPs and Leukocyte C-terminal Src kinase. Our results identify a PD-1 inhibitory mechanism that disrupts the cooperative TCR-pMHC-CD8 trimolecular interaction, which prevents CD8 from augmenting antigen recognition, explaining PD-1's potent inhibitory function and its value as a target for clinical intervention.
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3
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Ligand-engaged TCR is triggered by Lck not associated with CD8 coreceptor. Nat Commun 2014; 5:5624. [PMID: 25427562 PMCID: PMC4248239 DOI: 10.1038/ncomms6624] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2014] [Accepted: 10/20/2014] [Indexed: 11/28/2022] Open
Abstract
The earliest molecular events in T cell recognition have not yet been fully described, and the initial T cell receptor (TCR) triggering mechanism remains a subject of controversy. Here, using TIRF/FRET microscopy, we observe a two-stage interaction between TCR, CD8, and MHCp. There is an early (within seconds) interaction between CD3ζ and the coreceptor CD8 that is independent of the binding of CD8 to MHC, but that requires CD8 association with Lck. Later (several minutes) CD3ζ-CD8 interactions require CD8-MHC binding. Lck can be found free or bound to the coreceptor. This work indicates that the initial TCR triggering event is induced by free Lck.
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4
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Abstract
Phosphorylation of the T cell antigen receptor (TCR) by the tyrosine kinase Lck is an essential step in the activation of T cells. Because Lck is constitutively active, spatial organization may regulate TCR signaling. Here we found that Lck distributions on the molecular level were controlled by the conformational states of Lck, with the open, active conformation inducing clustering and the closed, inactive conformation preventing clustering. In contrast, association with lipid domains and protein networks were not sufficient or necessary for Lck clustering. Conformation-driven Lck clustering was highly dynamic, so that TCR triggering resulted in Lck clusters that contained phosphorylated TCRs but excluded the phosphatase CD45. Our data suggest that Lck conformational states represent an intrinsic mechanism for the intermolecular organization of early T cell signaling.
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5
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Sunzenauer S, Zojer V, Brameshuber M, Tröls A, Weghuber J, Stockinger H, Schütz GJ. Determination of binding curves via protein micropatterning in vitro and in living cells. Cytometry A 2012; 83:847-54. [PMID: 23125142 DOI: 10.1002/cyto.a.22225] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 08/23/2012] [Accepted: 10/09/2012] [Indexed: 11/11/2022]
Abstract
Quantification of protein interactions in living cells is of key relevance for understanding cellular signaling. With current techniques, however, it is difficult to determine binding affinities and stoichiometries of protein complexes in the plasma membrane. We introduce here protein micropatterning as a convenient and versatile method for such investigations. Cells are grown on surfaces containing micropatterns of capture antibody to a bait protein, so that the bait gets rearranged in the live cell plasma membrane. Upon interaction with the bait, the fluorescent prey follows the micropatterns, which can be readout with fluorescence microscopy. In this study, we addressed the interaction between Lck and CD4, two central proteins in early T-cell signaling. Binding curves were recorded using the natural fluctuations in the Lck expression levels. Surprisingly, the binding was not saturable up to the highest Lck expression levels: on average, a single CD4 molecule recruited more than nine Lck molecules. We discuss the data in view of protein- and lipid-mediated interactions.
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Affiliation(s)
- Stefan Sunzenauer
- Biophysics Institute, Johannes Kepler University Linz, A-4040 Linz, Austria
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6
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Rossy J, Williamson DJ, Gaus K. How does the kinase Lck phosphorylate the T cell receptor? Spatial organization as a regulatory mechanism. Front Immunol 2012; 3:167. [PMID: 22723799 PMCID: PMC3377954 DOI: 10.3389/fimmu.2012.00167] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 06/04/2012] [Indexed: 11/25/2022] Open
Abstract
T cell signaling begins with the ligation of the T cell antigen receptor (TCR) by a cognate peptide and the phosphorylation of the receptor’s immunoreceptor tyrosine-based activation motif domains by the kinase Lck. However, the canonical receptor model is insufficient to explain how the constitutively active kinase Lck can discriminate between non-ligated and ligated TCRs. Here, we discuss the factors that are thought to regulate the spatial distribution of the TCR and Lck, and therefore critically influence TCR signaling initiation.
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Affiliation(s)
- Jérémie Rossy
- Centre for Vascular Research, University of New South Wales, Sydney, NSW, Australia
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7
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Fournier M, Peyrou M, Bourgoin L, Maeder C, Tchou I, Foti M. CD4 dimerization requires two cysteines in the cytoplasmic domain of the molecule and occurs in microdomains distinct from lipid rafts. Mol Immunol 2010; 47:2594-603. [DOI: 10.1016/j.molimm.2010.06.010] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 05/06/2010] [Accepted: 06/21/2010] [Indexed: 01/27/2023]
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8
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Xu T, Chen L, Shang X, Cui L, Luo J, Chen C, Ba X, Zeng X. Critical role of Lck in L-selectin signaling induced by sulfatides engagement. J Leukoc Biol 2008; 84:1192-201. [PMID: 18653462 DOI: 10.1189/jlb.0208084] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Recruitment of leukocytes onto inflamed tissues is an important physiological event, in which L-selectin plays an essential role in initial leukocyte capture and at the same time, triggers cell signaling. Lck is a member of the Src family of protein tyrosine kinases and is critical for T cell activation triggered by receptor ligation. Here, we demonstrated that Lck was associated directly with and phosphorylated the L-selectin cytoplasmic tail upon L-selectin engagement with sulfatides. Through the direct interaction with ZAP-70 and c-Abl via its Src homology 2 (SH2) and SH3 domains, Lck organized a signaling complex at the cytoplasmic tail of L-selectin. In the cells with Lck knockdown by small interfering RNA treatment, L-selectin signaling was suppressed dramatically, as indicated by reduced phosphorylation of c-Abl and ZAP-70. Re-expression of wild-type or constitutively active but not kinase-dead murine Lck rescued the phosphorylation completely, but the SH2 domain mutant or the SH3/SH2 double mutant of murine Lck had no effect. These results suggest that Lck plays a critical role in L-selectin signaling upon sulfatides stimulation.
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Affiliation(s)
- Ting Xu
- Northeast Normal University, Changchun, People's Republic of China
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9
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Abstract
Recent advances in our understanding of the mechanisms of T-cell activation, migration to inflammatory sites, and pathologic disease processes triggered the development of a wide variety of T-cell-targeted signaling inhibitors, which have different targets and modes of action. Depending on the distribution and the role of targets in disease processes, T-cell inhibitors exhibit different levels of efficacy and potential side effects. This review outlines target molecules to which T-cell inhibitors have been developed, their efficacy, and potential safety concerns of T-cell inhibitors.
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Affiliation(s)
- Jonghwa Won
- Molecular Immunology Division, Mogam Biotechnology Research Institute, Gyounggi-Do, South Korea.
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10
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Kristensen O, Guenat S, Dar I, Allaman-Pillet N, Abderrahmani A, Ferdaoussi M, Roduit R, Maurer F, Beckmann JS, Kastrup JS, Gajhede M, Bonny C. A unique set of SH3-SH3 interactions controls IB1 homodimerization. EMBO J 2006; 25:785-97. [PMID: 16456539 PMCID: PMC1383563 DOI: 10.1038/sj.emboj.7600982] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 01/10/2006] [Indexed: 12/22/2022] Open
Abstract
Islet-brain 1 (IB1 or JIP-1) is a scaffold protein that interacts with components of the c-Jun N-terminal kinase (JNK) signal-transduction pathway. IB1 is expressed at high levels in neurons and in pancreatic beta-cells, where it controls expression of several insulin-secretory components and secretion. IB1 has been shown to homodimerize, but neither the molecular mechanisms nor the function of dimerization have yet been characterized. Here, we show that IB1 homodimerizes through a novel and unique set of Src homology 3 (SH3)-SH3 interactions. X-ray crystallography studies show that the dimer interface covers a region usually engaged in PxxP-mediated ligand recognition, even though the IB1 SH3 domain lacks this motif. The highly stable IB1 homodimer can be significantly destabilized in vitro by three individual point mutations directed against key residues involved in dimerization. Each mutation reduces IB1-dependent basal JNK activity in 293T cells. Impaired dimerization also results in a reduction in glucose transporter type 2 expression and in glucose-dependent insulin secretion in pancreatic beta-cells. Taken together, these results indicate that IB1 homodimerization through its SH3 domain has pleiotropic effects including regulation of the insulin secretion process.
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Affiliation(s)
- Ole Kristensen
- Biostructural Research, Department of Medicinal Chemistry, The Danish University of Pharmaceutical Sciences, Copenhagen, Denmark.
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11
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Viard M, Parolini I, Rawat SS, Fecchi K, Sargiacomo M, Puri A, Blumenthal R. The role of glycosphingolipids in HIV signaling, entry and pathogenesis. Glycoconj J 2005; 20:213-22. [PMID: 15090735 DOI: 10.1023/b:glyc.0000024253.48791.d9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although HIV uses CD4 and coreceptors (CCR5 and CXCR4) for productive infection of T cells, glycosphingolipids (GSL) may play ancillary roles in lymphoid and non-lymphoid cells. Interactions of the HIV Envelope Glycoprotein (Env) with GSL may help HIV in various steps of its pathogenesis. Physical-chemical aspects of the interactions between HIV Env and GSL leading to CD4-dependent entry into lymphocytes, the role of GSL in HIV transcytosis, and CD4-independent entry into non-lymphoid cells are reviewed. An overview of signaling properties of HIV receptors is provided with some speculation on how GSL may play a role in these events by virtue of being in membrane rafts. Finally, we summarize how interactions between HIV and coreceptors leading to signaling and/or fusion can be analyzed by the use of various tyrosine kinase and cytoskeletal inhibitors.
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Affiliation(s)
- Mathias Viard
- Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD, USA
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12
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Fragoso R, Ren D, Zhang X, Su MWC, Burakoff SJ, Jin YJ. Lipid raft distribution of CD4 depends on its palmitoylation and association with Lck, and evidence for CD4-induced lipid raft aggregation as an additional mechanism to enhance CD3 signaling. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:913-21. [PMID: 12517957 DOI: 10.4049/jimmunol.170.2.913] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
By mutagenesis, we demonstrated that the palmitoylation of the membrane-proximal Cys(396) and Cys(399)of CD4, and the association of CD4 with Lck contribute to the enrichment of CD4 in lipid rafts. Ab cross-linking of CD4 induces an extensive membrane patching on the T cell surface, which is related to lipid raft aggregation. The lipid raft localization of CD4 is critical for CD4 to induce the aggregation of lipid rafts. The localization of CD4 in lipid rafts also correlates to the ability of CD4 to enhance receptor tyrosine phosphorylation. Thus, our data suggest that CD4-induced aggregation of lipid rafts may play an additional role in CD4 signaling besides its adhesion to MHC molecules and association with Lck.
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Affiliation(s)
- Roben Fragoso
- Skirball Institute of Biomedical Research, New York University School of Medicine, New York 10016, USA
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13
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Src, Fyn, and Yes are not required for neuromuscular synapse formation but are necessary for stabilization of agrin-induced clusters of acetylcholine receptors. J Neurosci 2001. [PMID: 11312300 DOI: 10.1523/jneurosci.21-09-03151.2001] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Mice deficient in src and fyn or src and yes move and breathe poorly and die perinatally, consistent with defects in neuromuscular function. Src and Fyn are associated with acetylcholine receptors (AChRs) in muscle cells, and Src and Yes can act downstream of ErbB2, suggesting roles for Src family kinases in signaling pathways regulating neuromuscular synapse formation. We studied neuromuscular synapses in src(-/-); fyn(-/-) and src(-/-); yes(-/-) mutant mice and found that muscle development, motor axon pathfinding, clustering of postsynaptic proteins, and synapse-specific transcription are normal in these double mutants, showing that these pairs of kinases are not required for early steps in synapse formation. We generated muscle cell lines lacking src and fyn and found that neural agrin and laminin-1 induced normal clustering of AChRs and that agrin induced normal tyrosine phosphorylation of the AChR beta subunit in the absence of Src and Fyn. Another Src family member, most likely Yes, was associated with AChRs and phosphorylated by agrin in myotubes lacking Src and Fyn, indicating that Yes may compensate for the loss of Src and Fyn. Nevertheless, PP1 and PP2, inhibitors of Src-class kinases, did not inhibit agrin signaling, suggesting that Src class kinase activity is dispensable for agrin-induced clustering and tyrosine phosphorylation of AChRs. AChR clusters, however, were less stable in myotubes lacking Src and Fyn but not in PP1- or PP2-treated wild-type cells. These data show that the stabilization of agrin-induced AChR clusters requires Src and Fyn and suggest that the adaptor activities, rather than the kinase activities, of these kinases are essential for this stabilization.
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14
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Van Drenth C, Jenkins A, Ledwich L, Ryan TC, Mashikian MV, Brazer W, Center DM, Cruikshank WW. Desensitization of CXC chemokine receptor 4, mediated by IL-16/CD4, is independent of p56lck enzymatic activity. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:6356-63. [PMID: 11086073 DOI: 10.4049/jimmunol.165.11.6356] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CCR5 and CXC chemokine receptor 4 (CXCR4) are coreceptors for CD4 as defined by HIV-1 glycoprotein (gp) 120 binding. Pretreatment of T cells with gp120 results in modulation of both CCR5 and CXCR4 responsiveness, which is dependent upon p56(lck) enzymatic activity. The recent findings that pretreatment of T cells with a natural CD4 ligand, IL-16, could alter cellular responsiveness to macrophage-inflammatory protein-1ss (MIP-1ss) stimulation, prompted us to investigate whether IL-16 could also alter CXCR4 signaling. These studies demonstrate that IL-16/CD4 signaling in T lymphocytes also results in loss of stromal derived factor-1alpha (SDF-1alpha)/CXCR4-induced chemotaxis; however, unlike MIP-1ss/CCR5, the effects were not reciprocal. There was no effect on eotaxin/CCR3-induced chemotaxis. Desensitization of CXCR4 by IL-16 required at least 10-15 min pretreatment; no modulation of CXCR4 expression was observed, nor was SDF-1alpha binding altered. Using murine T cell hybridomas transfected to express native or mutated forms of CD4, it was determined that IL-16/CD4 induces a p56(lck)-dependent inhibitory signal for CXCR4, which is independent of its tyrosine catalytic activity. By contrast, IL-16/CD4 desensitization of MIP-1ss/CCR5 responses requires p56(lck) enzymatic activity. IL-16/CD4 inhibition of SDF-1alpha/CXCR4 signals requires the presence of the Src homology 3 domain of p56(lck) and most likely involves activation of phosphatidylinositol-3 kinase. These studies indicate the mechanism of CXCR4 receptor desensitization induced by a natural ligand for CD4, IL-16, is distinct from the inhibitory effects induced by either gp120 or IL-16 on CCR5.
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Affiliation(s)
- C Van Drenth
- Pulmonary Center, Boston University School of Medicine, Boston, MA 02118, USA
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15
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Matache C, Stefanescu M, Onu A, Tanaseanu S, Matei I, Frade R, Szegli G. p56lck activity and expression in peripheral blood lymphocytes from patients with systemic lupus erythematosus. Autoimmunity 1999; 29:111-20. [PMID: 10433072 DOI: 10.3109/08916939908995380] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
In this study we analyzed the activity and the expression of p56lck protein tyrosine kinase in peripheral blood lymphocytes (PBLs) from systemic lupus erythematosus (SLE) patients and from healthy donors. The p56lck activity, determined by a non-radioactive Tyrosine Kinase Assay Kit, was significantly higher in active SLE PBLs and discriminated this group of patients from inactive SLE patients (p = 0.002) and healthy donors (p = 0.009). p56lck level decreased in SLE lymphocytes (especially for inactive SLE lymphocytes, p = 0.005) when compared to healthy donors. These differences were also reflected by the specific activity of p56lck that was clearly elevated in active SLE lymphocytes when compared to inactive SLE (p = 0.022) or healthy donors lymphocytes (p = 0.006). A positive correlation between the activity of p56lck and the tyrosine phosphorylation level in active SLE lymphocytes was found.
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Affiliation(s)
- C Matache
- Department of Immunology, Cantacuzino Institute, Bucharest, Romania
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16
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Denny MF, Kaufman HC, Chan AC, Straus DB. The lck SH3 domain is required for activation of the mitogen-activated protein kinase pathway but not the initiation of T-cell antigen receptor signaling. J Biol Chem 1999; 274:5146-52. [PMID: 9988764 DOI: 10.1074/jbc.274.8.5146] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Initiation of T-cell antigen receptor (TCR) signaling is dependent upon the activity of protein tyrosine kinases. The Src family kinase Lck is required for the initial events in TCR signaling, such as the phosphorylation of the TCR complex and the activation of ZAP-70, but little is known of its role in downstream signaling. Expression of a mutated form of Lck lacking SH3 domain function (LckW97A) in the Lck-deficient T-cell line JCaM1 revealed a requirement for Lck beyond the initiation of TCR signaling. In cells expressing LckW97A, stimulation of the TCR failed to activate the mitogen-activated protein kinase (MAPK) pathway, despite normal TCR zeta chain phosphorylation, ZAP-70 recruitment, and ZAP-70 activation. Activation of extracellular signal-regulated kinase (ERK) and MAPK kinase (MEK), as well as the induction of CD69 expression, was greatly impaired in JCaM1/LckW97A cells. In contrast, the phosphorylation of phospholipase Cgamma1 (PLCgamma1) and corresponding elevations in intracellular calcium concentration ([Ca2+]i) were intact. Thus, cells expressing LckW97A exhibit a selective defect in the activation of the MAPK pathway. These results demonstrate that Lck has a role in the activation of signaling pathways beyond the initiation of TCR signaling and suggest that the MAPK pathway may be selectively controlled by regulating the function of Lck.
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Affiliation(s)
- M F Denny
- Department of Medicine and Pathology, University of Chicago, Chicago, Illinois 60637, USA
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17
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Eshhar Z, Fitzer-Attas CJ. Tyrosine kinase chimeras for antigen-selective T-body therapy. Adv Drug Deliv Rev 1998; 31:171-182. [PMID: 10837624 DOI: 10.1016/s0169-409x(97)00100-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Protein tyrosine kinases (PTKs) transmit activation signals in almost every cell type, including immune effector cells. The aberrant or constitutive activation of PTKs can often cause neoplastic transformation. The use of chimeric receptors based on PTKs may enable us to elucidate the signaling pathways of normal immune cells and other cell types, and the abnormal events that can lead to malignant transformation. In this review, we focus on antigen specific chimeric PTKs in which antibody-derived scFv are joined to the Syk family of PTKs. These chimeric receptors yielded reagents that can selectively redirect immune effector cells and specifically activate them to produce cytokines or lyse their target. The advantages of using such PTK-based chimeras to redirect lymphocytes to tumor targets and their potential as an immunotherapeutic approach to malignant disease is discussed.
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Affiliation(s)
- Z Eshhar
- Department of Immunology, The Weizmann Institute of Science, Rehovot 76100, Israel
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18
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Schwartzberg PL, Xing L, Hoffmann O, Lowell CA, Garrett L, Boyce BF, Varmus HE. Rescue of osteoclast function by transgenic expression of kinase-deficient Src in src-/- mutant mice. Genes Dev 1997; 11:2835-44. [PMID: 9353253 PMCID: PMC316651 DOI: 10.1101/gad.11.21.2835] [Citation(s) in RCA: 241] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/1997] [Accepted: 08/26/1997] [Indexed: 02/05/2023]
Abstract
The Src tyrosine kinase has been implicated in a wide variety of signal transduction pathways, yet despite the nearly ubiquitous expression of c-src, src-/- mice show only one major phenotype-osteopetrosis caused by an intrinsic defect in osteoclasts, the cells responsible for resorbing bone. To explore further the role of Src both in osteoclasts and other cell types, we have generated transgenic mice that express the wild-type and mutated versions of the chicken c-src proto-oncogene from the promoter of tartrate resistant acid phosphatase (TRAP), a gene that is expressed highly in osteoclasts. We demonstrate here that expression of a wild-type transgene in only a limited number of tissues can fully rescue the src-/- phenotype. Surprisingly, expression of kinase-defective alleles of c-src also reduces osteopetrosis in src-/- animals and partially rescues a defect in cytoskeletal organization observed in src-/- osteoclasts. These results suggest that there are essential kinase-independent functions for Src in vivo. Biochemical examination of osteoclasts from these mice suggest that Src may function in part by recruiting or activating other tyrosine kinases.
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Affiliation(s)
- P L Schwartzberg
- National Cancer Institute, University of Texas Health Science Center, San Antonio, Texas 78284, USA.
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