201
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Goto E, Ishido S, Sato Y, Ohgimoto S, Ohgimoto K, Nagano-Fujii M, Hotta H. c-MIR, a human E3 ubiquitin ligase, is a functional homolog of herpesvirus proteins MIR1 and MIR2 and has similar activity. J Biol Chem 2003; 278:14657-68. [PMID: 12582153 DOI: 10.1074/jbc.m211285200] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Kaposi's sarcoma associated-herpes virus encodes two proteins, MIR (modulator of immune recognition) 1 and 2, which are involved in the evasion of host immunity. MIR1 and 2 have been shown to function as an E3 ubiquitin ligase for immune recognition-related molecules (e.g. major histocompatibility complex class I, B7-2, and ICAM-1) through the BKS (bovine herpesvirus 4, Kaposi's sarcoma associated-herpes virus, and Swinepox virus) subclass of plant homeodomain (PHD) domain, termed the BKS-PHD domain. Here we show that the human genome also encodes a novel BKS-PHD domain-containing protein that functions as an E3 ubiquitin ligase and whose putative substrate is the B7-2 co-stimulatory molecule. This novel E3 ubiquitin ligase was designated as c-MIR (cellular MIR) based on its functional and structural similarity to MIR1 and 2. Forced expression of c-MIR induced specific down-regulation of B7-2 surface expression through ubiquitination, rapid endocytosis, and lysosomal degradation of the target molecule. This specific targeting was dependent upon the binding of c-MIR to B7-2. Replacing the BKS-PHD domain of MIR1 with the corresponding domain of c-MIR did not alter MIR1 function. The discovery of c-MIR, a novel E3 ubiquitin ligase, highlights the possibility that viral immune regulatory proteins originated in the host genome and presents unique functions of BKS-PHD domain-containing proteins in mammals.
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Affiliation(s)
- Eiji Goto
- Division of Microbiology, Department of Genome Sciences, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan
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202
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Dustin ML. Regulation of T cell migration through formation of immunological synapses: the stop signal hypothesis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2003; 512:191-201. [PMID: 12405204 DOI: 10.1007/978-1-4615-0757-4_25] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis and Department of Pathology, Skirball Institute of Molecular Medicine, New York University School of Medicine, NY 10016, USA
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203
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Lee SJE, Hori Y, Chakraborty AK. Low T cell receptor expression and thermal fluctuations contribute to formation of dynamic multifocal synapses in thymocytes. Proc Natl Acad Sci U S A 2003; 100:4383-8. [PMID: 12671067 PMCID: PMC153563 DOI: 10.1073/pnas.0630563100] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2002] [Accepted: 01/29/2003] [Indexed: 11/18/2022] Open
Abstract
Mature T cell activation and selection of immature T cells (thymocytes) are both initiated by binding of T cell receptor (TCR) molecules on the surface of T cells to MHC peptide (MHCp) molecules on the surface of antigen-presenting cells. Recent experiments have shown that the spatial pattern of receptors and ligands in the intercellular junction (synapse) is different during thymocyte selection compared with mature T cell activation. Using a statistical mechanical model, we show that lower TCR expression in thymocytes contributes to effecting these differences. An analogy with the phase behavior of simple fluids helps clarify how, for low TCR expression, thermal fluctuations lead to the dynamic synapse patterns observed for thymocytes. We suggest that a different synapse pattern resulting from lower TCR expression, which could mediate differential signaling, may be the reason why TCR expression level is low in thymocytes.
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Affiliation(s)
- Sung-Joo E Lee
- Biophysics Graduate Group, University of California, Berkeley, CA 94720, USA
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204
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Acuto O, Mise-Omata S, Mangino G, Michel F. Molecular modifiers of T cell antigen receptor triggering threshold: the mechanism of CD28 costimulatory receptor. Immunol Rev 2003; 192:21-31. [PMID: 12670392 DOI: 10.1034/j.1600-065x.2003.00034.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
CD28 was thought to represent a prototypic membrane receptor responsible for delivering the classically defined 'second signal' needed to avoid T cell paralysis when recognizing antigen presented by appropriate antigen presenting cells (APCs). Almost two decades after its molecular identification, the mechanism by which this 'second receptor' facilitates clonal expansion and differentiation upon antigen encounter is still not fully elucidated. There may be at least two reasons for this partially gray picture: the use of nonphysiological experimental conditions to study it and the fact that the action of CD28 may be partly masked by the presence of additional T cell surface receptors that also provide some costimulatory signals, although not equivalent to the one delivered through CD28. Thus, instead of aging, the study of CD28 is still a topical subject. What is appearing through work of recent years is that far from being purely qualitative, the CD28 signal provides a key quantitative contribution to potently boost the T cell antigen receptor (TCR) signal. In other words, CD28 is in part a signaling 'sosia' of the TCR. Also, it is clear now that CD28 operates via multiple molecular effects. Still, what we do not understand is the 'qualitative' part of this signal, perhaps due to lack of identification of unique signaling components and/or pathways activated by CD28 only. Here we review a series of recent findings pointing towards novel avenues to better understand the molecular basis of CD28 function.
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Affiliation(s)
- Oreste Acuto
- Molecular Immunology Unit, Department of Immunology, Institut Pasteur, Paris, France.
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205
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Stefanová I, Hemmer B, Vergelli M, Martin R, Biddison WE, Germain RN. TCR ligand discrimination is enforced by competing ERK positive and SHP-1 negative feedback pathways. Nat Immunol 2003; 4:248-54. [PMID: 12577055 DOI: 10.1038/ni895] [Citation(s) in RCA: 356] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2002] [Accepted: 01/14/2003] [Indexed: 12/27/2022]
Abstract
Functional discrimination between structurally similar self and foreign antigens is a main attribute of adaptive immunity. Here we describe two feedback mechanisms in T lymphocytes that together sharpen and amplify initial signaling differences related to the quality of T cell receptor (TCR) engagement. Weakly binding ligands predominantly trigger a negative feedback loop leading to rapid recruitment of the tyrosine phosphatase SHP-1, followed by receptor desensitization through inactivation of Lck kinase. In contrast, strongly binding ligands efficiently activate a positive feedback circuit involving Lck modification by ERK, preventing SHP-1 recruitment and allowing the long-lasting signaling necessary for gene activation. The characteristics of these pathways suggest that they constitute an important part of the mechanism allowing T cells to discriminate between self and foreign ligands.
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Affiliation(s)
- Irena Stefanová
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, 10 Center Dr., MSC-1892, Bethesda, Maryland 20892-1892, USA
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206
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Abstract
Adaptive immunity depends on antigen-specific activation of resting lymphocytes. Using high-resolution live-cell imaging, a single ligand has been found to trigger a biochemical response in T cells. On the basis of this and other recent findings, a 'pseudodimer' with one foreign- and one self-antigen-engaged receptor linked via a CD4 molecule has been proposed as the fundamental unit of effective T-cell signaling.
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Affiliation(s)
- Ronald N Germain
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bldg 10, Rm 11N311, 10 Center Drive MSC-1892, Bethesda, MD 20892-1892, USA.
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207
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Hiltbold EM, Poloso NJ, Roche PA. MHC class II-peptide complexes and APC lipid rafts accumulate at the immunological synapse. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:1329-38. [PMID: 12538693 DOI: 10.4049/jimmunol.170.3.1329] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Activation of CD4(+) Th cells requires their cognate interaction with APCs bearing specific relevant MHC class II-peptide complexes. This cognate interaction culminates in the formation of an immunological synapse that contains the various proteins and lipids required for efficient T cell activation. We now show that APC lipid raft membrane microdomains contain specific class II-peptide complexes and serve as platforms that deliver these raft-associated class II molecules to the immunological synapse. APC rafts are required for T cell:APC conjugate formation and T cell activation at low densities of relevant class II-peptide complexes, a requirement that can be overcome at high class II-peptide density. Analysis of confocal microscopy images revealed that over time APC lipid rafts, raft-associated relevant class II-peptide complexes, and even immunologically irrelevant class II molecules accumulate at the immunological synapse. As the immunological synapse matures, relevant class II-peptide complexes are sorted to a central region of the interface, while irrelevant class II molecules are excluded from this site. We propose that T cell activation is facilitated by recruitment of MHC class II-peptide complexes to the immunological synapse by virtue of their constitutive association with lipid raft microdomains.
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Affiliation(s)
- Elizabeth M Hiltbold
- Experimental Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
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208
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Stefanova I, Dorfman JR, Tsukamoto M, Germain RN. On the role of self-recognition in T cell responses to foreign antigen. Immunol Rev 2003; 191:97-106. [PMID: 12614354 DOI: 10.1034/j.1600-065x.2003.00006.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The key role of the thymus in shaping the peripheral T cell receptor (TCR) repertoire has been appreciated for nearly a quarter of a century. For most of that time, a single model has dominated thinking about the physiological role of the positive selection process mediated by TCR recognition of self-peptides and major histocompatibility complex (MHC) molecules. This developmental filter was believed to populate secondary lymphoid tissues with T cells bearing receptors best able to recognize unknown foreign peptides associated with the particular allelic forms of the MHC molecules present in an individual. More recently, self-recognition has been suggested to regulate the viability of naïve T cells. Here we focus on new results indicating that a critical contribution of positive selection to host defense is insuring that each peripheral T cell can use self-recognition to (i) enhance TCR signaling sensitivity upon foreign antigen recognition and (ii) augment the clonal expansion that accompanies limiting foreign antigen display at early points in an infectious process. We also detail new insights into the intracellular signaling circuitry that underlies the effective discrimination between low- and high-quality ligands of the TCR and speculate on how this design might facilitate an additional contribution of self-recognition to T cell activation in the presence of foreign stimuli.
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Affiliation(s)
- Irena Stefanova
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA
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209
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Fuller CL, Braciale VL, Samelson LE. All roads lead to actin: the intimate relationship between TCR signaling and the cytoskeleton. Immunol Rev 2003; 191:220-36. [PMID: 12614363 DOI: 10.1034/j.1600-065x.2003.00004.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Regardless of cell type, the regulation of the actin cytoskeleton is tightly linked to vital biological properties such as polarity, motility, cell-cell contact, exocytosis and proliferation. In the immune system, where rapid and efficient response to antigen-provoked stimuli is crucial, an overwhelming amount of data implicate the actin cytoskeleton and its regulators as central to immune function. Increasingly, the cytoskeleton is considered an essential amplification step in T cell receptor (TCR)-, costimulatory-, and integrin-mediated signaling. Advances in genetic manipulation and confocal imaging have led to a keener appreciation of the importance of TCR signal integration by the actin cytoskeleton. This review outlines recent advances in elucidating the regulation of T cell function through the actin cytoskeleton. We also examine intriguing parallels between the immune system and other models of cytoskeletal regulation.
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Affiliation(s)
- Claudette L Fuller
- Laboratory of Cellular and Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD 20892-4255, USA
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210
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Abstract
After a brief overview of the themes and variations that occur in the family of receptors containing immunoreceptor tyrosine-based activation motifs (ITAMs), and of recent structural data on the ligand-binding subunits of these receptors, we use these data to revisit how information on the state and quality of occupancy of the binding site of the T cell antigen receptor (TCR) is conveyed to the proximal components of the TCR transduction cassette.
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Affiliation(s)
- Bernard Malissen
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Marseille, France.
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211
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Sieling PA, Chung W, Duong BT, Godowski PJ, Modlin RL. Toll-like receptor 2 ligands as adjuvants for human Th1 responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:194-200. [PMID: 12496400 DOI: 10.4049/jimmunol.170.1.194] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Bacterial lipopeptides (bLPs) are increasingly used as adjuvants to activate cell-mediated immune responses to foreign Ags. To explore mechanisms whereby bLPs adjuvant T cell responses, we stimulated human PBMCs with bLPs. We found that bLPs stimulate T cells to proliferate and produce IFN-gamma in an accessory cell-dependent manner and in the absence of exogenous protein Ags. The ability of bLPs to stimulate T cell proliferation was Toll-like receptor 2 dependent and required IL-12, interaction with costimulatory molecules, and MHC proteins. Our data suggest that bLPs adjuvant adaptive Th1 responses by enhancing Ag presentation of endogenous peptides.
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Affiliation(s)
- Peter A Sieling
- Department of Medicine, Division of Dermatology, David Gefffen School of Medicine, University of California, Los Angeles, CA 90095, USA.
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212
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Badour K, Zhang J, Shi F, McGavin MKH, Rampersad V, Hardy LA, Field D, Siminovitch KA. The Wiskott-Aldrich syndrome protein acts downstream of CD2 and the CD2AP and PSTPIP1 adaptors to promote formation of the immunological synapse. Immunity 2003; 18:141-54. [PMID: 12530983 DOI: 10.1016/s1074-7613(02)00516-2] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The Wiskott-Aldrich syndrome protein (WASp) couples actin cytoskeletal rearrangement to T cell activation, but the mechanisms involved are unknown. Here, we show that antigen-induced formation of T cell:APC conjugates and synapses is abrogated in WASp-deficient T cells and that CD2 engagement evokes interactions between the proline-rich region required for WASp translocation to the synapse and the PSTPIP1 adaptor SH3 domain and between the PSTPIp1 coiled-coil domain and both CD2 and another CD2-binding adaptor, CD2AP. The induced colocalization of these proteins at the synapse is disrupted by expression of coiled-coil domain-deleted PSTPIP1. These data, together with the impairment in CD2-induced actin polymerization observed in WASp-deficient cells, suggest that PSTPIP1 acts downstream of CD2/CD2AP to link CD2 engagement to the WASp-evoked actin polymerization required for synapse formation and T cell activation.
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Affiliation(s)
- Karen Badour
- Department of Medical Genetics and Microbiology, University of Toronto, 600 University Avenue, Toronto, M5G 1X5 Ontario, Canada
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213
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Dao T, Blander JM, Sant'Angelo DB. Recognition of a specific self-peptide: self-MHC class II complex is critical for positive selection of thymocytes expressing the D10 TCR. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 170:48-54. [PMID: 12496382 DOI: 10.4049/jimmunol.170.1.48] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
We examined the specificity of positive and negative selection by using transgenic mice carrying a variant of the D10 TCR. We demonstrate that a point mutation at position 51 within the CDR2alpha segment significantly reduces the avidity of this TCR for its cognate ligand, but does not impact recognition of nonself MHC class II molecules. Although structural studies have suggested that this TCR site interacts with the MHC class II beta-chain, the avidity of this TCR for its ligand and the function of the T cell can be reconstituted by a point mutation in the bound antigenic peptide. These data demonstrate that the bound peptide can indirectly alter TCR interactions by influencing MHC structure. Remarkably, reducing the avidity of this TCR for a specific antigenic peptide-MHC ligand has a dramatic impact on thymic selection. Positive selection of thymocytes expressing this TCR is nearly completely blocked, whereas negative selection on allogenic MHC class II molecules remains intact. Therefore, the recognition of self that promotes positive selection of the D10 TCR is highly peptide-specific.
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MESH Headings
- Alleles
- Animals
- Arginine/genetics
- Autoantigens/metabolism
- Cell Differentiation/immunology
- Cell Line
- Complementarity Determining Regions/genetics
- Complementarity Determining Regions/physiology
- Conalbumin/metabolism
- Down-Regulation/genetics
- Down-Regulation/immunology
- Epitopes, T-Lymphocyte/biosynthesis
- Epitopes, T-Lymphocyte/genetics
- Glycine/genetics
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/metabolism
- Histocompatibility Antigens Class II/physiology
- Leucine/genetics
- Lymphocyte Count
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Peptides/immunology
- Peptides/metabolism
- Point Mutation
- Receptors, Antigen, T-Cell, alpha-beta/antagonists & inhibitors
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Serine/genetics
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
- Transgenes/immunology
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Affiliation(s)
- Tao Dao
- Laboratory of T Cell Immunobiology, Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10021, USA
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214
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Rachmilewitz J, Lanzavecchia A. A temporal and spatial summation model for T-cell activation: signal integration and antigen decoding. Trends Immunol 2002; 23:592-5. [PMID: 12464571 DOI: 10.1016/s1471-4906(02)02342-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Commitment of T cells to cytokine production and proliferation requires sustained (up to several hours) T-cell receptor (TCR) signaling that is achieved through serial engagement. This article proposes a kinetic model, adopted from neurons, which is based on the local temporal summation of successive signals. This model offers an explanation for how signals originating from serially triggered TCRs are accumulated and integrated over the period required for T-cell activation, given that each TCR-evoked signal is rapidly lost. The principal innovation of this model is the suggestion that signaling intermediates produced by serially triggered TCRs are not simply sustained but are incrementally built up. Several phenomena related to T-cell behavior and self-nonself discrimination are discussed.
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Affiliation(s)
- Jacob Rachmilewitz
- Goldyne Savad Institute of Gene Therapy, Hadassah University Hospital, PO Box 12000, Jerusalem, 91120, Israel.
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215
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Wetzel SA, McKeithan TW, Parker DC. Live-cell dynamics and the role of costimulation in immunological synapse formation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6092-101. [PMID: 12444111 DOI: 10.4049/jimmunol.169.11.6092] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Using transfected fibroblasts expressing both wild-type I-E(k) and green fluorescent protein-tagged I-E(k) with covalently attached antigenic peptide, we have monitored movement of specific MHC:peptide complexes during CD4(+) T cell-APC interactions by live-cell video microscopy. Ag recognition occurs within 30 s of T cell-APC contact, as shown by a sharp increase in cytoplasmic calcium ion concentration. Within 1 min, small MHC:peptide clusters form in the contact zone that coalesce into an immunological synapse over 3-20 min. When T cells conjugated to APC move across the APC surface, they appear to drag the synapse with them. This system was used to examine the role of costimulation in the formation of the immunological synapse. Blocking CD80/CD28 or ICAM-1/LFA-1 interactions alters synapse morphology and reduces the area and density of accumulated complexes. These reductions correlate with reduced T cell proliferation, while CD69 and CD25 expression and TCR down-modulation remain unaffected. Thus, costimulation is essential for normal mature immunological synapse formation.
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Affiliation(s)
- Scott A Wetzel
- Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland 97239, USA
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216
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Théry C, Duban L, Segura E, Véron P, Lantz O, Amigorena S. Indirect activation of naïve CD4+ T cells by dendritic cell-derived exosomes. Nat Immunol 2002; 3:1156-62. [PMID: 12426563 DOI: 10.1038/ni854] [Citation(s) in RCA: 707] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2002] [Accepted: 10/01/2002] [Indexed: 01/01/2023]
Abstract
Dendritic cells (DCs) secrete vesicles of endosomal origin, called exosomes, that bear major histocompatibility complex (MHC) and T cell costimulatory molecules. Here, we found that injection of antigen- or peptide-bearing exosomes induced antigen-specific naïve CD4+ T cell activation in vivo. In vitro, exosomes did not induce antigen-dependent T cell stimulation unless mature CD8alpha- DCs were also present in the cultures. These mature DCs could be MHC class II-negative, but had to bear CD80 and CD86. Therefore, in addition to carrying antigen, exosomes promote the exchange of functional peptide-MHC complexes between DCs. Such a mechanism may increase the number of DCs bearing a particular peptide, thus amplifying the initiation of primary adaptive immune responses.
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Affiliation(s)
- Clotilde Théry
- INSERM U520, Institut Curie, 12 rue Lhomond, 75005 Paris, France
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217
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Schott E, Ploegh HL. Mouse MHC class I tetramers that are unable to bind to CD8 reveal the need for CD8 engagement in order to activate naive CD8 T cells. Eur J Immunol 2002; 32:3425-34. [PMID: 12432573 DOI: 10.1002/1521-4141(200212)32:12<3425::aid-immu3425>3.0.co;2-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Although the role of CD8 as a supplier of lck is unchallenged, its role in contributing to the formation of a stable complex between class I molecules and the TCR, as well as its role as an adhesion molecule, is less clear. To address the role of CD8/MHC-I interactions, we generated tetramers composed of H2-K(b) molecules with mutations in the alpha 3 domain of H2-K(b) that abolish CD8 binding. We show that the ability of tetramers to stain and activate CD8 T cells is strongly dependent on binding of CD8 to the same class I molecule engaged by the TCR. We characterize a mutation in the alpha 3 domain that results in H2-K(b) molecules capable of staining specific CD8 T cells with little ensuing activation. Although CD8 to some extent serves an adhesive function, this contribution is modest and does not substitute for lack of binding of CD8 to the class I molecule engaged by the TCR. We show that CD8 and the TCR associate in a process independent of binding of CD8 to class I. Our data support the notion that CD8 is required to form a stable complex between class I and the TCR.
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Affiliation(s)
- Eckart Schott
- Department of Pathology, Harvard Medical School, Boston, USA
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218
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Stefanová I, Dorfman JR, Germain RN. Self-recognition promotes the foreign antigen sensitivity of naive T lymphocytes. Nature 2002; 420:429-34. [PMID: 12459785 DOI: 10.1038/nature01146] [Citation(s) in RCA: 309] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2002] [Accepted: 09/04/2002] [Indexed: 11/09/2022]
Abstract
Major histocompatibility complex (MHC) class I and II molecules are highly polymorphic proteins that bind and present foreign peptides to the clonally distributed alphabeta receptors (TCR) of T lymphocytes. As a population, the immature T lymphocytes generated in the thymus express a very diverse set of TCR specificities. A process of positive selection filters this broad repertoire to optimize peripheral T cells for antigen recognition in the context of available MHC products. Only those precursor T cells whose TCRs generate an adequate but not excessive signalling response to self-peptides bound to the expressed MHC proteins undergo successful maturation. Here we show that post-thymic self-recognition facilitates the antigen reactivity of mature T cells. Both experimental and physiological interruption of T-cell contact with self-peptide MHC ligands leads to a rapid decline in signalling and response sensitivity to foreign stimuli. Because the adaptive immune system must be recruited early in an infectious process when antigen is limiting, these findings suggest that positive selection ensures predictable T-cell recognition of available self-ligands, which in turn promotes efficient responses to pathogens.
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MESH Headings
- Animals
- Antibodies, Monoclonal/immunology
- Antibodies, Monoclonal/pharmacology
- Antigens/immunology
- Autoantigens/immunology
- Autoimmunity/drug effects
- CD4-Positive T-Lymphocytes/drug effects
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- DNA-Binding Proteins/genetics
- Histocompatibility Antigens Class II/genetics
- Histocompatibility Antigens Class II/immunology
- Ligands
- Mice
- Mice, Transgenic
- Phosphorylation
- Polymorphism, Genetic
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/immunology
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- Superantigens/immunology
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Affiliation(s)
- Irena Stefanová
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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219
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Hori Y, Raychaudhuri S, Chakraborty AK. Analysis of pattern formation and phase separation in the immunological synapse. J Chem Phys 2002. [DOI: 10.1063/1.1512642] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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220
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Moss WC, Irvine DJ, Davis MM, Krummel MF. Quantifying signaling-induced reorientation of T cell receptors during immunological synapse formation. Proc Natl Acad Sci U S A 2002; 99:15024-9. [PMID: 12415110 PMCID: PMC137538 DOI: 10.1073/pnas.192573999] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Productive T cell recognition of antigen-presenting cells (APCs) is normally accompanied by the formation of a cell-cell contact called the "immunological synapse." Our understanding of the steps leading up to this formation has been limited by the absence of tools for analyzing 3D surfaces and surface distributions as they change over time. Here we use a 3D fluorescence quantitation method to show that T cell receptors are recruited in bulk within the first minute after the onset of activation and with velocities ranging from 0.04 to 0.1 microm/s; a speed significantly greater than unrestricted diffusion. Our method reveals a second feature of this reorientation: a conformational change as the T cell pushes more total membrane into the interface creating a larger contact area for additional receptors. Analysis of individual T cell receptor velocities using a single-particle tracking method confirms our velocity measurement. This method should permit the quantitation of other dynamic membrane events and the associated movement of cell-surface molecules.
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Affiliation(s)
- William C Moss
- Department of Microbiology and Immunology, Stanford University School of Medicine and Howard Hughes Medical Institute, CA 94305, USA
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221
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Chmielowski B, Pacholczyk R, Kraj P, Kisielow P, Ignatowicz L. Presentation of antagonist peptides to naive CD4+ T cells abrogates spatial reorganization of class II MHC peptide complexes on the surface of dendritic cells. Proc Natl Acad Sci U S A 2002; 99:15012-7. [PMID: 12411579 PMCID: PMC137536 DOI: 10.1073/pnas.222463499] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
By using dendritic cells (DCs) transduced with retroviruses encoding covalent A(b)beta/peptide fusion proteins tagged with fluorescent proteins, we followed the relocation of class II MHC molecules loaded with agonist or null peptides during the onset of activation of naive and effector CD4(+) T cells. Clusters of T cell receptor (TCR)/CD3 complex formed in parallel with clusters of agonist class II MHC/peptide complexes on the surface of DCs. However, activation of naive but not effector T cells was accompanied by expulsion of the null class II MHC/peptide complexes from the T cell-DC interface. These effects were perturbed in the presence of exogenously supplied antagonist peptide. These results suggest that interference with selective relocation of agonist and null MHC/peptide complexes in the immunological synapse contributes to the inhibitory effect of antagonist peptides on the response of naive CD4(+) T cells to agonist ligands.
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Affiliation(s)
- Bartosz Chmielowski
- Institute of Molecular Medicine and Genetics, Medical College of Georgia, Augusta 30912, USA
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222
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Vyas YM, Maniar H, Dupont B. Visualization of signaling pathways and cortical cytoskeleton in cytolytic and noncytolytic natural killer cell immune synapses. Immunol Rev 2002; 189:161-78. [PMID: 12445273 DOI: 10.1034/j.1600-065x.2002.18914.x] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Recent applications of imaging approaches and other methods of cell biology have provided high-resolution visualization of the location of fluorescent proteins in living and fixed cells during cell-cell interactions between lymphocytes, antigen presenting cells and target cells. We review the composition and dynamics of molecular and cytoskeletal events occurring during natural killer cell interactions with susceptible and nonsusceptible target cells. The natural killer cell immune synapse and the concomitant changes in cytoskeletal components and cytoplasmic organelles are described. The findings are compared with the observations made in T helper cells and cytotoxic T cells. It is concluded that the cytolytic immune synapses display spatial-temporal dynamics that are accelerated as compared with T helper cells. In addition, the cytolytic conjugates have unique characteristics relating to their effector function. Furthermore, the natural killer cell immune synapses in cytolytic and noncytolytic interactions are distinctly different and display patterns consistent with characteristic signaling pathways identified in biochemical studies of disrupted cells. The precise relationship between different stages of the natural killer cell immune synapse formation and progression in signal transduction pathways is yet to be established.
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Affiliation(s)
- Yatin M Vyas
- Immunology Program, Sloan-Kettering Institute for Cancer Research, New York, NY 10021, USA
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223
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Delon J, Stoll S, Germain RN. Imaging of T-cell interactions with antigen presenting cells in culture and in intact lymphoid tissue. Immunol Rev 2002; 189:51-63. [PMID: 12445265 DOI: 10.1034/j.1600-065x.2002.18906.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The development of an effective immune response requires cell-cell contact between T cells and antigen-bearing cells of several types (dendritic cells, B cells, infected tissue cells). Recent advances in light microscopy have led to intense investigation of the molecular events that accompany these cell interactions, especially the redistribution of membrane proteins into discrete organized subdomains within the zone of cell-cell contact termed the 'immunological synapse'. Here we discuss two aspects of our own studies in this area. First, we highlight results from our in vitro analysis of the role of the cytoskeletal ezrin, radixin, moesin adapter proteins in the exclusion of CD43 from the well-defined T cell receptor (TCR) and integrin-rich zones of the synapse. Based on the molecular mechanism uncovered in this work, we propose a new model for how TCR-signaled changes in cytoskeletal organization indirectly influence both protein distributions and the efficiency of signaling between T cell and presenting cell. We then discuss the development of a new method for dynamic visualization of T cell - dendritic cell interactions in intact lymphoid tissue. The remarkable longevity of monogamous lymphocyte-presenting cell interactions is discussed, differences between our observations and those of others are laid out in detail, and prospects for future application of this technical approach to analysis of early immune responses in lymphoid organs and of effector lymphocyte function in tissues are presented.
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Affiliation(s)
- Jérôme Delon
- Lymphocyte Biology Section, Laboratory of Immunology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892-1892, USA
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224
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Baldari CT. Antigen receptor signaling under the Tuscan sun. Nat Immunol 2002; 3:1053-5. [PMID: 12407415 DOI: 10.1038/ni1102-1053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Cosima T Baldari
- Department of Evolutionary Biology, University of Siena, Via A. Moro 2, 53100 Siena, Italy.
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225
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Wülfing C, Tskvitaria-Fuller I, Burroughs N, Sjaastad MD, Klem J, Schatzle JD. Interface accumulation of receptor/ligand couples in lymphocyte activation: methods, mechanisms, and significance. Immunol Rev 2002; 189:64-83. [PMID: 12445266 DOI: 10.1034/j.1600-065x.2002.18907.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Cellular interaction is vital to the activation of most lymphocytes. At the interface between the lymphocyte and the cell that activates it, multiple receptor/ligand pairs accumulate in distinct patterns. This accumulation is intriguing, as it is likely to shape the quality of receptor signaling and thereby lymphocyte behavior. Here we address such receptor/ligand accumulation with an emphasis on T and natural killer (NK) cells. First, we discuss the strengths and limitations of commonly used approaches to visualize receptor/ligand accumulation. Second, we discuss two principal mechanisms of receptor and ligand translocation, diffusion and cytoskeletal transport, as understanding these mechanisms can be invaluable in the determination of the significance of receptor/ligand accumulation. We show that the extent of receptor/ligand accumulation at the T cell/antigen presenting cell interface is dominated by diffusion for all but the lowest affinity interactions, while patterning of these receptors/ligands within the interface is strongly influenced by cytoskeletal transport. Third, we discuss two specific issues in lymphocyte receptor/ligand accumulation. We review the abundant but frequently controversial data on T cell receptor (TCR)/major histocompatibility complex (MHC) accumulation and suggest that central TCR/MHC accumulation is a mediator of efficient T cell activation. In the investigation of NK cell/target cell interactions, we characterize the often tentative NK cell/target cell couple maintenance, as it creates a major obstacle in studying receptor/ligand accumulation.
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Affiliation(s)
- Christoph Wülfing
- Center for Immunology, Department of Cell Biology, Program in Immunology, UT Southwestern Medical Center, Dallas, TX 75390-9093, USA.
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226
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Vogt AB, Spindeldreher S, Kropshofer H. Clustering of MHC-peptide complexes prior to their engagement in the immunological synapse: lipid raft and tetraspan microdomains. Immunol Rev 2002; 189:136-51. [PMID: 12445271 DOI: 10.1034/j.1600-065x.2002.18912.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Protein reorganization at the interface of a T cell and an antigen-presenting cell (APC) plays an important role in T cell activation. Imaging techniques reveal that reorganization of particular receptor-ligand pairs gives rise to an intercellular junction, termed the immunological synapse. In this synapse antigenic peptides associated with major histocompatibility complex (MHC) molecules form multimolecular arrays on the APC side, engaging an equivalent number of clustered T cell receptors (TCRs) on the T cell. The accumulation of MHC molecules carrying cognate peptide in the APC-T cell interface was thought to depend on the specificity and presence of TCRs. Recent evidence, however, suggests that the APC is equipped to preorganize MHC-peptide complexes in the absence of T cells. To this end, MHC molecules become incorporated into two types of membrane microdomains: (i) cholesterol- and glycosphingolipid-enriched domains, denoted lipid rafts, that preconcentrate MHC class II molecules; and (ii) microdomains made up of tetraspan proteins, such as CD9, CD63, CD81 or CD82, that mediate enrichment of MHC class II molecules loaded with a select set of peptides. It follows that the integrity, composition and dynamics of these microdomains are candidate determinants favoring activation or silencing of T cells.
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Affiliation(s)
- Anne B Vogt
- Roche Center for Medical Genomics, F. Hoffmann-La Roche, Ltd, Basel, Switzerland
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227
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Abstract
A synapse is a stable adhesive junction between two cells across which information is relayed by directed secretion. The nervous system and immune system utilize these specialized cell surface contacts to directly convey and transduce highly controlled secretory signals between their constituent cell populations. Each of these synaptic types is built around a microdomain structure comprising central active zones of exocytosis and endocytosis encircled by adhesion domains. Surface molecules that may be incorporated into and around the active zones contribute to modulation of the functional state of the synapse.
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Affiliation(s)
- Michael L Dustin
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, Department of Pathology, New York University School of Medicine, New York, NY 10016 USA.
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228
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Irvine DJ, Purbhoo MA, Krogsgaard M, Davis MM. Direct observation of ligand recognition by T cells. Nature 2002; 419:845-9. [PMID: 12397360 DOI: 10.1038/nature01076] [Citation(s) in RCA: 587] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2002] [Accepted: 08/05/2002] [Indexed: 11/09/2022]
Abstract
The activation of T cells through interaction of their T-cell receptors with antigenic peptide bound to major histocompatibility complex (MHC) on the surface of antigen presenting cells (APCs) is a crucial step in adaptive immunity. Here we use three-dimensional fluorescence microscopy to visualize individual peptide-I-E(k) class II MHC complexes labelled with the phycobiliprotein phycoerythrin in an effort to characterize T-cell sensitivity and the requirements for forming an immunological synapse in single cells. We show that T cells expressing the CD4 antigen respond with transient calcium signalling to even a single agonist peptide-MHC ligand, and that the organization of molecules in the contact zone of the T cell and APC takes on the characteristics of an immunological synapse when only about ten agonists are present. This sensitivity is highly dependent on CD4, because blocking this molecule with antibodies renders T cells unable to detect less than about 30 ligands.
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Affiliation(s)
- Darrell J Irvine
- Department of Microbiology & Immunology and The Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, California 94305, USA
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229
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Abstract
A framework for quantitative analysis of the mechanisms underlying immunological synapse assembly has been recently developed. This model uses partial differential equations to describe the binding interactions of receptors and ligands, with the constraint that they are embedded in apposed deformable membranes linked to a cytoskeletal complex.
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Affiliation(s)
- Sung-Joo E Lee
- Biophysics Graduate Group, Dept of Chemistry, University of California, Berkeley, CA, USA
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230
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Burroughs NJ, Wülfing C. Differential segregation in a cell-cell contact interface: the dynamics of the immunological synapse. Biophys J 2002; 83:1784-96. [PMID: 12324401 PMCID: PMC1302272 DOI: 10.1016/s0006-3495(02)73944-1] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Receptor-ligand couples in the cell-cell contact interface between a T cell and an antigen-presenting cell form distinct geometric patterns and undergo spatial rearrangement within the contact interface. Spatial segregation of the antigen and adhesion receptors occurs within seconds of contact, central aggregation of the antigen receptor then occurring over 1-5 min. This structure, called the immunological synapse, is becoming a paradigm for localized signaling. However, the mechanisms driving its formation, in particular spatial segregation, are currently not understood. With a reaction diffusion model incorporating thermodynamics, elasticity, and reaction kinetics, we examine the hypothesis that differing bond lengths (extracellular domain size) is the driving force behind molecular segregation. We derive two key conditions necessary for segregation: a thermodynamic criterion on the effective bond elasticity and a requirement for the seeding/nucleation of domains. Domains have a minimum length scale and will only spontaneously coalesce/aggregate if the contact area is small or the membrane relaxation distance large. Otherwise, differential attachment of receptors to the cytoskeleton is required for central aggregation. Our analysis indicates that differential bond lengths have a significant effect on synapse dynamics, i.e., there is a significant contribution to the free energy of the interaction, suggesting that segregation by differential bond length is important in cell-cell contact interfaces and the immunological synapse.
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231
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Lee SJE, Hori Y, Groves JT, Dustin ML, Chakraborty AK. Correlation of a dynamic model for immunological synapse formation with effector functions: two pathways to synapse formation. Trends Immunol 2002; 23:492-9. [PMID: 12297421 DOI: 10.1016/s1471-4906(02)02285-8] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
During antigen recognition by T cells different receptors and ligands form a pattern in the intercellular junction called the immunological synapse, which might be involved in T-cell activation. Recently, a synapse assembly model has been proposed, which enables the calculation of the propensity for synapse assembly driven by membrane-constrained protein binding interactions. We bring together model predictions of mature synapse assembly with data on the dependence of T-cell responses on T-cell receptor (TCR)-MHC-peptide (pMHC) binding kinetics. Predictions of mature synapse assembly, based on TCR-pMHC binding kinetics, correlate well with observed cytokine responses by T cells bearing the relevant TCR but not with cytotoxic T lymphocyte-mediated killing. We discuss the suggested different role for the synapse in pre- and post-nuclear activation events in T cells. The view of immunological synapse assembly given here emphasizes the importance of both the on and off rates for the TCR-pMHC interaction and in this context recent data on a positive role for analogs of self-peptides in synapse assembly is considered.
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Affiliation(s)
- Sung-Joo E Lee
- Biophysics Graduate Group, Dept of Chemistry, University of California, Berkeley, CA, USA
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232
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Coombs D, Kalergis AM, Nathenson SG, Wofsy C, Goldstein B. Activated TCRs remain marked for internalization after dissociation from pMHC. Nat Immunol 2002; 3:926-31. [PMID: 12244312 DOI: 10.1038/ni838] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Accepted: 08/15/2002] [Indexed: 11/09/2022]
Abstract
To assess the roles of serial engagement and kinetic proofreading in T cell receptor (TCR) internalization, we have developed a mathematical model of this process. Our determination of TCR down-regulation for an array of TCR mutants, interpreted in the context of the model, has provided new information about peptide-induced TCR internalization. The amount of TCR down-regulation increases to a maximum value and then declines as a function of the half-life of the bond between the TCR and peptide-major histocompatibility complex (pMHC). The model shows that this behavior, which reflects competition between serial engagement and kinetic proofreading, arises only if it is postulated that activated TCRs remain marked for internalization after dissociation from pMHC. The model also predicts that because of kinetic proofreading, the range of TCR-pMHC-binding half-lives required for T cell activation depends on the concentrations and localization of intracellular signaling molecules. We show here that kinetic proofreading provides an explanation for the different requirements for activation observed in naïve and memory T cells.
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Affiliation(s)
- Daniel Coombs
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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233
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Diehn M, Alizadeh AA, Rando OJ, Liu CL, Stankunas K, Botstein D, Crabtree GR, Brown PO. Genomic expression programs and the integration of the CD28 costimulatory signal in T cell activation. Proc Natl Acad Sci U S A 2002; 99:11796-801. [PMID: 12195013 PMCID: PMC129348 DOI: 10.1073/pnas.092284399] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Optimal activation of T cells requires effective occupancy of both the antigen-specific T cell receptor and a second coreceptor such as CD28. We used cDNA microarrays to characterize the genomic expression program in human peripheral T cells responding to stimulation of these receptors. We found that CD28 agonists alone elicited few, but reproducible, changes in gene expression, whereas CD3 agonists elicited a multifaceted temporally choreographed gene expression program. The principal effect of simultaneous engagement of CD28 was to increase the amplitude of the CD3 transcriptional response. The induced genes whose expression was most enhanced by costimulation were significantly enriched for known targets of nuclear factor of activated T cells (NFAT) transcription factors. This enhancement was nearly abolished by blocking the nuclear translocation of NFATc by using the calcineurin inhibitor FK506. CD28 signaling promoted phosphorylation, and thus inactivation, of the NFAT nuclear export kinase glycogen synthase kinase-3 (GSK3), coincident with enhanced dephosphorylation of NFATc proteins. These results provide a detailed picture of the transcriptional program of T cell activation and suggest that enhancement of transcriptional activation by NFAT, through inhibition of its nuclear export, plays a key role in mediating the CD28 costimulatory signal.
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Affiliation(s)
- Maximilian Diehn
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
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234
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Huang J, Lo PF, Zal T, Gascoigne NRJ, Smith BA, Levin SD, Grey HM. CD28 plays a critical role in the segregation of PKC theta within the immunologic synapse. Proc Natl Acad Sci U S A 2002; 99:9369-73. [PMID: 12077322 PMCID: PMC123147 DOI: 10.1073/pnas.142298399] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/17/2002] [Indexed: 11/18/2022] Open
Abstract
The signaling pathways that lead to the localization of cellular protein to the area of interaction between T cell and antigen-presenting cell and the mechanism by which these molecules are further sorted to the peripheral supramolecular activation cluster or central supramolecular activation cluster regions of the immunologic synapse are poorly understood. In this study, we investigated the functional involvement of CD28 costimulation in the T cell receptor (TCR)-mediated immunologic synapse formation with respect to protein kinase C (PKC)theta; localization. We showed that CD3 crosslinking alone was sufficient to induce PKC theta; capping in naive CD4(+) T cells. Studies with pharmacologic inhibitors and knockout mice showed that the TCR-derived signaling that drives PKC theta; membrane translocation requires the Src family kinase, Lck, but not Fyn. In addition, a time course study of the persistence of T cell molecules to the immunologic synapse indicated that PKC theta;, unlike TCR, persisted in the synapse for at least 4 h, a time that is sufficient for commitment of a T cell to cell division. Finally, by using TCR-transgenic T cells from either wild-type or CD28-deficient mice, we showed that CD28 expression was required for the formation of the mature immunologic synapse, because antigen stimulation of CD28(-) T cells led to a diffuse pattern of localization of PKC theta; and lymphocyte function-associated antigen-1 in the immunologic synapse, in contrast to the central supramolecular activation cluster localization of PKC theta; in CD28(+) T cells.
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Affiliation(s)
- Jianyong Huang
- Division of Immunochemistry, La Jolla Institute for Allergy and Immunology, 10355 Science Center Drive, San Diego, CA 92121, USA
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235
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Bromley SK, Dustin ML. Stimulation of naïve T-cell adhesion and immunological synapse formation by chemokine-dependent and -independent mechanisms. Immunology 2002; 106:289-98. [PMID: 12100716 PMCID: PMC1782736 DOI: 10.1046/j.1365-2567.2002.01441.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chemokines adsorbed to the cell surface play an important role in the initial interactions of T cells with endothelial cells, and may also have a role in T-cell interactions with dendritic cells. Therefore, we examined the effect of surface-adsorbed chemokines on the interaction of naïve murine splenic T cells with supported bilayers containing intercellular adhesion molecule (ICAM)-1, or with bone marrow-derived cultured dendritic cells in the presence and absence of relevant MHC-peptide complexes. Naïve T cells formed immunological synapses, defined as a ring of lymphocyte function associated (LFA)-1-ICAM-1 interactions surrounding a central cluster of MHC-peptide complexes, on supported planar bilayers containing ICAM-1 and relevant MHC-peptide complexes. Chemokines stimulated an increase in the percentage of naïve cells that adhered to ICAM-1, but did not increase the average number of LFA-1-ICAM-1 interactions in the contact area. In contrast, relevant MHC-peptide complexes resulted in a small increase in the proportion of interacting T cells, but stimulated an 8-fold increase in the number of LFA-1-ICAM-1 interactions in each contact formed. Naïve T cells displayed a significant basal adhesion to bone marrow dendritic cells that was further increased when relevant chemokines were adsorbed to the dendritic cell surface. However, basal and antigen-stimulated T-cell adhesion to dendritic cells was not sensitive to pertussis toxin. Thus, there are chemokine-independent mechanisms that initiate adhesion between T cells and dendritic cells.
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Affiliation(s)
- Shannon K Bromley
- Graduate Program in Immunology, Washington University School of Medicine, St. Louis, MO, USA
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236
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Affiliation(s)
- Daniel M Davis
- Department of Biological Sciences, Sir Alexander Fleming Building, Imperial College of Science, Technology and Medicine, London SW7 2AZ, UK.
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237
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Abstract
Less than five years ago it was reported that cell surface molecules at the contact site between CD4 T cells and antigen-presenting cells redistribute into distinct patterns, forming an organized interface termed the immunological synapse. More recently, similar reorganized interfaces have been observed with CD8 T cells and NK cells, suggesting that they may be a common feature of lymphocyte activation. Although there has been some advance in our understanding of the mechanisms underlying this redistribution, its purpose remains unclear and controversial.
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238
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Richie LI, Ebert PJR, Wu LC, Krummel MF, Owen JJT, Davis MM. Imaging synapse formation during thymocyte selection: inability of CD3zeta to form a stable central accumulation during negative selection. Immunity 2002; 16:595-606. [PMID: 11970882 DOI: 10.1016/s1074-7613(02)00299-6] [Citation(s) in RCA: 122] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
TCR signaling can result in cell fates ranging from activation to tolerance to apoptosis. Organization of molecules in an "immunological synapse" between mature T cells and APCs correlates with the strength of TCR signaling. To investigate synapse formation during thymic selection, we have established a reaggregate system in which molecular recruitment of GFP fusion proteins to thymocyte:stromal cell interfaces can be visualized in real time. We demonstrate that negative selection is associated with efficient conjugate formation and rapid recruitment of p56(lck) and CD3zeta to an immunological synapse. Interestingly, CD3zeta-GFP does not accumulate at the center of the synapse, as in mature T cells, but at the periphery across a wide range of ligand densities. This implicates differences in synapse geometry in initiation of alternate signals downstream of the TCR.
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Affiliation(s)
- Lauren I Richie
- Program in Immunology, Howard Hughes Medical Institute, Stanford University School of Medicine, Stanford, CA 94305, USA
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239
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Chakraborty AK. How and why does the immunological synapse form? Physical chemistry meets cell biology. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2002; 2002:pe10. [PMID: 11880685 DOI: 10.1126/stke.2002.122.pe10] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
During T lymphocyte (T cell) recognition of an antigen, a highly organized and specific pattern of membrane proteins forms in the junction between the T cell and the antigen-presenting cell (APC). This specialized cell-cell junction is called the immunological synapse. It is several micrometers large and forms over many minutes. A plethora of experiments are being performed to study the mechanisms that underlie synapse formation and the way in which information transfer occurs across the synapse. The wealth of experimental data that is beginning to emerge must be understood within a mechanistic framework if it is to prove useful in developing modalities to control the immune response. Quantitative models can complement experiments in the quest for such a mechanistic understanding by suggesting experimentally testable hypotheses. Here, a quantitative synapse assembly model is described. The model uses concepts developed in physical chemistry and cell biology and is able to predict the spatiotemporal evolution of cell shape and receptor protein patterns observed during synapse formation. Attention is directed to how the juxtaposition of model predictions and experimental data has led to intriguing hypotheses regarding the role of null and self peptides during synapse assembly, as well as correlations between T cell effector functions and the robustness of synapse assembly. We remark on some ways in which synergistic experiments and modeling studies can improve current models, and we take steps toward a better understanding of information transfer across the T cell-APC junction.
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Affiliation(s)
- Arup K Chakraborty
- Department of Chemical Engineering, University of California, Physical Bioscience and Materials Science Divisions, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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240
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Krummel MF, Davis MM. Dynamics of the immunological synapse: finding, establishing and solidifying a connection. Curr Opin Immunol 2002; 14:66-74. [PMID: 11790534 DOI: 10.1016/s0952-7915(01)00299-0] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A coordinated series of molecular interactions leads to the establishment of an immunological synapse. Migrating lymphocytes scan antigen-processing cells and are made to stop upon recognition of their specific ligand. Microclusters of TCRs/CD4 form over a large contact site, then TCRs coalesce. Coalescence occurs in response to signals generated in the first encounters and in response to costimulatory signaling. The cytoskeleton rearranges and concentric rings of coreceptors and integrins surround the TCRs. This unexpected level of complexity of co-clustering and exclusion in the interface has generated much interest in the functional consequences of signaling and/or immune effector function.
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Affiliation(s)
- Matthew F Krummel
- Department of Pathology, University of California at San Francisco, San Francisco, CA 94143-0511, USA.
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241
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Dustin ML. The immunological synapse. ARTHRITIS RESEARCH 2002; 4 Suppl 3:S119-25. [PMID: 12110130 PMCID: PMC3240135 DOI: 10.1186/ar559] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/26/2001] [Accepted: 12/11/2001] [Indexed: 01/04/2023]
Abstract
T-cell activation requires interaction of T-cell antigen receptors with proteins of the major histocompatibility complex (antigen). This interaction takes place in a specialized cell-cell junction referred to as an immunological synapse. The immunological synapse contains at least two functional domains: a central cluster of engaged antigen receptors and a surrounding ring of adhesion molecules. The segregation of the T-cell antigen receptor (TCR) and adhesion molecules is based on size, with the TCR interaction spanning 15 nm and the lymphocyte-function-associated antigen-1 (LFA-1) interaction spanning 30-40 nm between the two cells. Therefore, the synapse is not an empty gap, but a space populated by both adhesion and signaling molecules. This chapter considers four aspects of the immunological synapse: the role of migration and stop signals, the role of the cytoskeleton, the role of self-antigenic complexes, and the role of second signals.
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Affiliation(s)
- Michael L Dustin
- Department of Pathology, New York University School of Medicine, Skirball Institute for Biomolecular Medicine, New York 10016, USA.
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