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Nakayama H, Nagafuku M, Suzuki A, Iwabuchi K, Inokuchi JI. The regulatory roles of glycosphingolipid-enriched lipid rafts in immune systems. FEBS Lett 2018; 592:3921-3942. [PMID: 30320884 DOI: 10.1002/1873-3468.13275] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/09/2018] [Accepted: 10/10/2018] [Indexed: 01/04/2023]
Abstract
Lipid rafts formed by glycosphingolipids (GSLs) on cellular membranes play important roles in innate and adaptive immunity. Lactosylceramide (LacCer) forms lipid rafts on plasma and granular membranes of human neutrophils. These LacCer-enriched lipid rafts bind directly to pathogenic components, such as pathogenic fungi-derived β-glucan and Mycobacteria-derived lipoarabinomannan via carbohydrate-carbohydrate interactions, and mediate innate immune responses to these pathogens. In contrast, a-series and o-series gangliosides form distinct rafts on CD4+ and CD8+ T cell subsets, respectively, contributing to the respective functions of these cells and stimulating adaptive immune responses through T cell receptors. These findings suggest that gangliosides play indispensable roles in T cell selection and activation. This Review introduces the involvement of GSL-enriched lipid rafts in innate and adaptive immunity.
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Affiliation(s)
- Hitoshi Nakayama
- Laboratory of Biochemistry, Juntendo University Faculty of Health Care and Nursing, Urayasu, Japan.,Institute for Environmental and Gender-specific Medicine, Juntendo University Graduate School of Medicine, Urayasu, Japan
| | - Masakazu Nagafuku
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Akemi Suzuki
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
| | - Kazuhisa Iwabuchi
- Laboratory of Biochemistry, Juntendo University Faculty of Health Care and Nursing, Urayasu, Japan.,Institute for Environmental and Gender-specific Medicine, Juntendo University Graduate School of Medicine, Urayasu, Japan.,Infection Control Nursing, Juntendo University Graduate School of Health Care and Nursing, Urayasu, Japan
| | - Jin-Ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Japan
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Inokuchi JI, Inamori KI, Kabayama K, Nagafuku M, Uemura S, Go S, Suzuki A, Ohno I, Kanoh H, Shishido F. Biology of GM3 Ganglioside. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2018; 156:151-195. [PMID: 29747813 DOI: 10.1016/bs.pmbts.2017.10.004] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Since the successful molecular cloning in 1998 of GM3 synthase (GM3S, ST3GAL5), the enzyme responsible for initiating biosynthesis of all complex gangliosides, the efforts of our research group have been focused on clarifying the physiological and pathological implications of gangliosides, particularly GM3. We have identified isoforms of GM3S proteins having distinctive lengths of N-terminal cytoplasmic tails, and found that these cytoplasmic tails define subcellular localization, stability, and in vivo activity of GM3S isoforms. Our studies of the molecular pathogenesis of type 2 diabetes, focused on interaction between insulin receptor and GM3 in membrane microdomains, led to a novel concept: type 2 diabetes and certain other lifestyle-related diseases are membrane microdomain disorders resulting from aberrant expression of gangliosides. This concept has enhanced our understanding of the pathophysiological roles of GM3 and related gangliosides in various diseases involving chronic inflammation, such as insulin resistance, leptin resistance, and T-cell function and immune disorders (e.g., allergic asthma). We also demonstrated an essential role of GM3 in murine and human auditory systems; a common pathological feature of GM3S deficiency is deafness. This is the first direct link reported between gangliosides and auditory functions.
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Affiliation(s)
- Jin-Ichi Inokuchi
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan.
| | - Kei-Ichiro Inamori
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | | | - Masakazu Nagafuku
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Satoshi Uemura
- Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Shinji Go
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Akemi Suzuki
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Isao Ohno
- Center for Medical Education, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Hirotaka Kanoh
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
| | - Fumi Shishido
- Institute of Molecular Biomembrane and Glycobiology, Tohoku Medical and Pharmaceutical University, Sendai, Miyagi, Japan
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P2X7 receptor promotes intestinal inflammation in chemically induced colitis and triggers death of mucosal regulatory T cells. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1183-1194. [PMID: 28286160 DOI: 10.1016/j.bbadis.2017.03.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Revised: 02/08/2017] [Accepted: 03/05/2017] [Indexed: 12/13/2022]
Abstract
P2X7 receptor activation contributes to inflammation development in different pathologies. We previously reported that the P2X7 receptor is over-expressed in the gut mucosa of patients with inflammatory bowel disease, and that P2X7 inhibition protects against chemically induced colitis. Here, we investigated in detail the role of the P2X7 receptor in inflammatory bowel disease development, by treating P2X7 knockout (KO) and WT mice with two different (and established) colitis inductors. P2X7 KO mice were protected against gut inflammation induced by 2,4,6-trinitrobenzenesulfonic acid or oxazolone, with no weight loss or gut histological alterations after treatment. P2X7 receptor knockout induced regulatory T cell accumulation in the colon, as evaluated by qRT-PCR for FoxP3 expression and immunostaining for CD90/CD45RBlow. Flow cytometry analysis of mesenteric lymph node cells showed that P2X7 activation (by ATP) triggered regulatory T cell death. In addition, such cells from P2X7 KO mice expressed more CD103, suggesting increased migration of regulatory T cells to the colon (relative to the WT). Our results show that the P2X7 has a key role during inflammation development in inflammatory bowel disease, by triggering the death and retention in the mesenteric lymph nodes of regulatory T cells that would otherwise promote immune system tolerance in the gut.
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Lam Hui K, Kwak SI, Upadhyaya A. Adhesion-dependent modulation of actin dynamics in Jurkat T cells. Cytoskeleton (Hoboken) 2013; 71:119-35. [DOI: 10.1002/cm.21156] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2013] [Revised: 10/21/2013] [Accepted: 10/29/2013] [Indexed: 01/06/2023]
Affiliation(s)
- King Lam Hui
- Department of Physics; University of Maryland; College Park Maryland 20742
| | - Sae In Kwak
- Department of Chemistry and Biochemistry; University of Maryland; College Park Maryland 20742
| | - Arpita Upadhyaya
- Department of Physics; University of Maryland; College Park Maryland 20742
- Institute for Physical Science and Technology, University of Maryland; College Park Maryland 20742
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Turk HF, Chapkin RS. Membrane lipid raft organization is uniquely modified by n-3 polyunsaturated fatty acids. Prostaglandins Leukot Essent Fatty Acids 2013; 88:43-7. [PMID: 22515942 PMCID: PMC3404206 DOI: 10.1016/j.plefa.2012.03.008] [Citation(s) in RCA: 141] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2012] [Revised: 03/27/2012] [Accepted: 03/28/2012] [Indexed: 01/20/2023]
Abstract
Fish oil, enriched in bioactive n-3 polyunsaturated fatty acids (PUFA), has been shown to play a role in prevention of colon cancer. The effects of n-3 PUFA are pleiotropic and multifaceted, resulting in an incomplete understanding of their molecular mechanisms of action. Here, we focus on a highly conserved mechanism of n-3 PUFA, which is the alteration of the organization of the plasma membrane. We highlight recent work demonstrating that enrichment of n-3 PUFA in the plasma membrane alters the lateral organization of membrane signaling assemblies (i.e. lipid rafts). This mechanism is central for n-3 PUFA regulation of downstream signaling, T-cell activation, transcriptional activation, and cytokine secretion. We conclude that these studies provide strong evidence for a predominant mechanism by which n-3 PUFA function in colon cancer prevention.
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Affiliation(s)
- Harmony F Turk
- Program in Integrative Nutrition and Complex Diseases and the Center for Environmental and Rural Health, Texas A&M University, College Station, TX 77843, USA
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Surls J, Nazarov-Stoica C, Kehl M, Olsen C, Casares S, Brumeanu TD. Increased membrane cholesterol in lymphocytes diverts T-cells toward an inflammatory response. PLoS One 2012; 7:e38733. [PMID: 22723880 PMCID: PMC3378591 DOI: 10.1371/journal.pone.0038733] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 05/11/2012] [Indexed: 11/23/2022] Open
Abstract
Cell signaling for T-cell growth, differentiation, and apoptosis is initiated in the cholesterol-rich microdomains of the plasma membrane known as lipid rafts. Herein, we investigated whether enrichment of membrane cholesterol in lipid rafts affects antigen-specific CD4 T-helper cell functions. Enrichment of membrane cholesterol by 40–50% following squalene administration in mice was paralleled by an increased number of resting CD4 T helper cells in periphery. We also observed sensitization of the Th1 differentiation machinery through co-localization of IL-2Rα, IL-4Rα, and IL-12Rβ2 subunits with GM1 positive lipid rafts, and increased STAT-4 and STAT-5 phosphorylation following membrane cholesterol enrichment. Antigen stimulation or CD3/CD28 polyclonal stimulation of membrane cholesterol-enriched, resting CD4 T-cells followed a path of Th1 differentiation, which was more vigorous in the presence of increased IL-12 secretion by APCs enriched in membrane cholesterol. Enrichment of membrane cholesterol in antigen-specific, autoimmune Th1 cells fostered their organ-specific reactivity, as confirmed in an autoimmune mouse model for diabetes. However, membrane cholesterol enrichment in CD4+Foxp3+ T-reg cells did not alter their suppressogenic function. These findings revealed a differential regulatory effect of membrane cholesterol on the function of CD4 T-cell subsets. This first suggests that membrane cholesterol could be a new therapeutic target to modulate the immune functions, and second that increased membrane cholesterol in various physiopathological conditions may bias the immune system toward an inflammatory Th1 type response.
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Affiliation(s)
- Jacqueline Surls
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Cristina Nazarov-Stoica
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Margaret Kehl
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Cara Olsen
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Sofia Casares
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- Infectious Diseases Directorate–Malaria Program, Naval Medical Research Center, Silver Spring, Maryland, United States of America
| | - Teodor-D. Brumeanu
- Department of Medicine, Division of Immunology and the Biostatistics Counseling Center, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail:
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Lee WT, Prasad A, Watson ARO. Anergy in CD4 memory T lymphocytes. II. Abrogation of TCR-induced formation of membrane signaling complexes. Cell Immunol 2012; 276:26-34. [PMID: 22663768 DOI: 10.1016/j.cellimm.2012.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 05/11/2012] [Accepted: 05/12/2012] [Indexed: 01/15/2023]
Abstract
Memory and naive CD4 T cells have unique regulatory pathways for self/non-self discrimination. A memory cell specific regulatory pathway was revealed using superantigens to trigger the TCR. Upon stimulation by bacterial superantigens, like staphylococcal enterotoxin B (SEB), TCR proximal signaling is impaired leading to clonal tolerance (anergy). In the present report, we show that memory cell anergy results from the sequestration of the protein tyrosine kinase ZAP-70 away from the TCR/CD3ζ chain. During SEB-induced signaling, ZAP-70 is excluded from both detergent-resistant membrane microdomains and the immunological synapse, thus blocking downstream signaling. We also show that the mechanism underlying memory cell anergy must involve Fyn kinase, given that the suppression of Fyn activity restores the movement of ZAP-70 to the immunological synapse, TCR proximal signaling, and cell proliferation. Thus, toleragens, including microbial toxins, may modulate memory responses by targeting the organizational structure of memory cell signaling complexes.
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Affiliation(s)
- William T Lee
- The Department of Biomedical Sciences, The School of Public Health, The University at Albany, Albany, New York 12201-0509, United States.
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Mechanisms behind functional avidity maturation in T cells. Clin Dev Immunol 2012; 2012:163453. [PMID: 22611418 PMCID: PMC3351025 DOI: 10.1155/2012/163453] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2011] [Accepted: 01/26/2012] [Indexed: 12/22/2022]
Abstract
During an immune response antigen-primed B-cells increase their antigen responsiveness by affinity maturation mediated by somatic hypermutation of the genes encoding the antigen-specific B-cell receptor (BCR) and by selection of higher-affinity B cell clones. Unlike the BCR, the T-cell receptor (TCR) cannot undergo affinity maturation. Nevertheless, antigen-primed T cells significantly increase their antigen responsiveness compared to antigen-inexperienced (naïve) T cells in a process called functional avidity maturation. This paper covers studies that describe differences in T-cell antigen responsiveness during T-cell differentiation along with examples of the mechanisms behind functional avidity maturation in T cells.
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Akhtar Khan N. Polyunsaturated fatty acids in the modulation of T-cell signalling. Prostaglandins Leukot Essent Fatty Acids 2010; 82:179-87. [PMID: 20189788 DOI: 10.1016/j.plefa.2010.02.023] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Indexed: 11/25/2022]
Abstract
n-3 polyunsaturated fatty acids (PUFA) have been shown to modulate immune responses. These agents, being considered as adjuvant immunosuppressants, have been used in the treatment of various inflammatory and autoimmune diseases. However, the molecular mechanisms of action of n-3 PUFA-induced immunosuppressive effects are not well-understood. Since exogenous n-3 PUFA, under in vitro and in vivo conditions, are efficiently incorporated into T-cell plasma membranes, a number of recent studies have demonstrated that these agents may modulate T-cell signalling. In this review, the interactions of n-3 PUFA with the second messenger cascade initiated during early and late events of T-cell activation are discussed. We particularly focus on how these fatty acids can modulate the production of diacylglycerol and the activation of protein kinase C, mitogen activated protein kinase, calcium signalling and translocation of transcriptional factors, implicated in the regulation of gene transcription in T-cells.
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Affiliation(s)
- Naim Akhtar Khan
- University of Burgundy, Department of Physiology, UPRES EA4183 Lipids and Cell Signalling, Faculty of Life Sciences, Dijon, France.
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Sigalov AB. The SCHOOL of nature: I. Transmembrane signaling. SELF/NONSELF 2010; 1:4-39. [PMID: 21559175 PMCID: PMC3091606 DOI: 10.4161/self.1.1.10832] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 11/30/2009] [Accepted: 12/01/2009] [Indexed: 11/19/2022]
Abstract
Receptor-mediated transmembrane signaling plays an important role in health and disease. Recent significant advances in our understanding of the molecular mechanisms linking ligand binding to receptor activation revealed previously unrecognized striking similarities in the basic structural principles of function of numerous cell surface receptors. In this work, I demonstrate that the Signaling Chain Homooligomerization (SCHOOL)-based mechanism represents a general biological mechanism of transmembrane signal transduction mediated by a variety of functionally unrelated single- and multichain activating receptors. within the SCHOOL platform, ligand binding-induced receptor clustering is translated across the membrane into protein oligomerization in cytoplasmic milieu. This platform resolves a long-standing puzzle in transmembrane signal transduction and reveals the major driving forces coupling recognition and activation functions at the level of protein-protein interactions-biochemical processes that can be influenced and controlled. The basic principles of transmembrane signaling learned from the SCHOOL model can be used in different fields of immunology, virology, molecular and cell biology and others to describe, explain and predict various phenomena and processes mediated by a variety of functionally diverse and unrelated receptors. Beyond providing novel perspectives for fundamental research, the platform opens new avenues for drug discovery and development.
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Affiliation(s)
- Alexander B Sigalov
- Department of Pathology; University of Massachusetts Medical School; Worcester, MA USA
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Signaling Chain Homooligomerization (SCHOOL) Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2008; 640:121-63. [DOI: 10.1007/978-0-387-09789-3_12] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
The plasma membranes of all eukaryotic cells contain heterogeneous self-organising intrinsically unstable liquid ordered domains or lipid assemblies in which key signal transduction proteins are localised. These assemblies are classified as 'lipid rafts' (10-200 nm), which are composed mostly of cholesterol and sphingolipid microdomains and therefore do not integrate well into the fluid phospholipid bilayers. In addition, caveolae represent a subtype of lipid raft macrodomain that form flask-shaped membrane invaginations containing structural proteins, i.e. caveolins. With respect to the diverse biological effects of long-chain PUFA, increasing evidence suggests that n-3 PUFA and perhaps conjugated fatty acids uniquely alter the basic properties of cell membranes. Because of its polyunsaturation, DHA and possibly conjugated linoleic acid are sterically incompatible with sphingolipid and cholesterol and, therefore, appear to alter lipid raft behaviour and protein function. The present review examines the evidence indicating that dietary sources of n-3 PUFA can profoundly alter the biochemical make up of lipid rafts/caveolae microdomains, thereby influencing cell signalling, protein trafficking and cell cytokinetics.
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Tether and trap: regulation of membrane-raft dynamics by actin-binding proteins. Nat Rev Immunol 2007; 7:889-96. [PMID: 17948020 DOI: 10.1038/nri2193] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The existence of plasma-membrane-raft microdomains has been widely debated during the past few years. However, it is clear that during lymphocyte stimulation a lipid-based reorganization occurs at the plasma membrane, with markers of the membrane rafts being selectively recruited to key active regions of the cell. Recent reports have demonstrated that membrane-raft dynamics are controlled by proteins that are linked to the actin cytoskeleton and have suggested a new model for the plasma membrane based on protein-lipid interactions. This new and dynamic view of the plasma membrane may improve our understanding of the complex process leading to cell polarization during lymphocyte migration and activation.
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Leitenberg D, Falahati R, Lu DD, Takeda A. CD45-associated protein promotes the response of primary CD4 T cells to low-potency T-cell receptor (TCR) stimulation and facilitates CD45 association with CD3/TCR and lck. Immunology 2007; 121:545-54. [PMID: 17428310 PMCID: PMC2265975 DOI: 10.1111/j.1365-2567.2007.02602.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Although it is clear that the CD45 tyrosine phosphatase is required for efficient T-cell activation and T-cell development, the factors that regulate CD45 function remain uncertain. Previous data have indicated that there is an association of CD45 with CD4 and the T-cell receptor (TCR) complex controlled by the variable ectodomain of CD45 and, following activation, by high- and low-potency peptides. This suggests that controlling substrate access to CD45 may be an important regulatory mechanism during T-cell activation. In the present study we have examined the role of the transmembrane adapter-like molecule CD45-associated protein (CD45-AP) in regulating the association of CD45 with CD3/TCR and lck, and in regulating primary CD4(+) T-lymphocyte activation. In CD4(+) T cells from CD45-AP-deficient mice, coimmunoprecipitation of CD45 with the CD3/TCR complex, in addition to lck, is significantly reduced compared with wild-type T cells. Functionally, this correlates with a decreased proliferative response, a decrease in interleukin (IL)-2 production, and a decrease in calcium flux upon stimulation with a low-potency altered peptide ligand. However, the response of CD45-AP-deficient T cells to stimulation with a high-avidity agonist peptide was largely intact, except for a modest decrease in IL-2 production. These data suggest that CD45-AP promotes or stabilizes the association of CD45 with substrates and regulates the threshold of T-cell activation.
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Affiliation(s)
- David Leitenberg
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University Medical Center, Washington, DC 20037, USA.
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Chapkin RS, Davidson LA, Ly L, Weeks BR, Lupton JR, McMurray DN. Immunomodulatory effects of (n-3) fatty acids: putative link to inflammation and colon cancer. J Nutr 2007; 137:200S-204S. [PMID: 17182826 DOI: 10.1093/jn/137.1.200s] [Citation(s) in RCA: 108] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Chronic inflammation and colorectal cancer are closely linked. Although the overall mechanisms of inflammation-associated gastrointestinal carcinogenesis are complex, it is clear that antiinflammatory therapy is efficacious against neoplastic progression and malignant conversion. From a dietary perspective, fish oil containing (n-3) polyunsaturated fatty acids (PUFAs) has antiinflammatory properties, but for years the mechanism has remained obscure. Of relevance to the immune system in the intestine, we showed that (n-3) PUFA feeding alters the balance between CD4+ T-helper (Th1 and Th2) subsets by directly suppressing Th1 cell development (i.e., clonal expansion). This is noteworthy because Th1 cells mediate inflammatory diseases and resistance to intracellular pathogens or allergic hypersensitivity, and Th2 cells mediate resistance to extracellular pathogens. Therefore, any changes induced by (n-3) PUFAs in T-cell subset balance and function are important because the outcome is expected to suppress the development of autoimmune diseases and possibly the occurrence of colon cancer. Precisely how the immunomodulatory effects of (n-3) PUFAs influence inflammation-associated colonic tumor development is the subject of an ongoing investigation.
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Affiliation(s)
- Robert S Chapkin
- Faculty of Nutrition, Center for Environmental and Rural Health, Texas A&M University, College Station, TX 77843, USA.
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Siddiqui RA, Harvey KA, Zaloga GP, Stillwell W. Modulation of lipid rafts by Omega-3 fatty acids in inflammation and cancer: implications for use of lipids during nutrition support. Nutr Clin Pract 2007; 22:74-88. [PMID: 17242459 DOI: 10.1177/011542650702200174] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Current understanding of biologic membrane structure and function is largely based on the concept of lipid rafts. Lipid rafts are composed primarily of tightly packed, liquid-ordered sphingolipids/cholesterol/saturated phospholipids that float in a sea of more unsaturated and loosely packed, liquid-disordered lipids. Lipid rafts have important clinical implications because many important membrane-signaling proteins are located within the raft regions of the membrane, and alterations in raft structure can alter activity of these signaling proteins. Because rafts are lipid-based, their composition, structure, and function are susceptible to manipulation by dietary components such as omega-3 polyunsaturated fatty acids and by cholesterol depletion. We review how alteration of raft lipids affects the raft/nonraft localization and hence the function of several proteins involved in cell signaling. We focus our discussion of raft-signaling proteins on inflammation and cancer.
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Affiliation(s)
- Rafat A Siddiqui
- Methodist Research Institute, Cellular Biochemistry, Indianapolis, IN 46202, USA.
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Lynch GW, Turville S, Carter B, Sloane AJ, Chan A, Muljadi N, Li S, Low L, Armati P, Raison R, Zoellner H, Williamson P, Cunningham A, Church WB. Marked differences in the structures and protein associations of lymphocyte and monocyte CD4: resolution of a novel CD4 isoform. Immunol Cell Biol 2006; 84:154-65. [PMID: 16519733 DOI: 10.1111/j.1440-1711.2005.01403.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structures, molecular interactions and functions of CD4 in a subset of T lymphocytes have been well characterized. The CD4 receptors of other cell types have, however, been poorly documented. We have previously shown that lymphocytes and monocytes/macrophages differ in their expression of CD4 monomers and dimers. In the present study, we have shown further significant differences. Variability in the blocking of CD4 mAb binding by sulfated polyanions indicated differences in exofacial CD4 structures. In contrast to the well-documented 55 kDa monomers in lymphocytic cells, monocytic cells were found to coexpress two monomer isoforms: the 55 kDa form and a novel 59 kDa species. Experimental uncoupling of CD4 disulfides indicated that the oxidized 55 kDa monomer could be converted to the 59 kDa form. This was achieved by chemical reduction of purified native or recombinant CD4, or in cell transfection experiments by mutation of cysteine to alanine in domain 1 (D1) (Cys16 or Cys84) and in domain 4 (D4) (Cys303 or Cys345). All of these modifications promote CD4 distension on SDS-PAGE analysis and indicate that, when CD4 inter-beta-sheet disulfides in the D1 and D4 Ig folds are disrupted, there is an unravelling of the oxidized form to an extended 59 kDa unfolded state. We hypothesize that this may be a transition-state, structural-intermediate in the formation of disulfide-linked homodimers. Also identified were CD4-tyrosine kinase dissimilarities in which lymphocyte CD4 associated with Lck, but monocyte CD4 associated with HcK. These findings show that there is complex heterogeneity in structures and interactions in the CD4 of T lymphocytes and monocytes.
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Affiliation(s)
- Garry W Lynch
- HIV-Protein Interactions Laboratory, Westmead Millennium Institute, Westmead, Australia.
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Hanlon A, Jang S, Salgame P. Cbl-b differentially regulates activation-induced apoptosis in T helper 1 and T helper 2 cells. Immunology 2006; 116:507-12. [PMID: 16313364 PMCID: PMC1802430 DOI: 10.1111/j.1365-2567.2005.02252.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
We previously reported that ligation of CD3 induces antiapoptotic signals in T helper 2 (Th2) cells, and in contrast causes Th1 cells to undergo apoptosis. Here we show that Cbl-b is accountable for the unequal response, revealing a previously unknown cell-specific regulatory function for the molecule. Absence of Cbl-b resulted in resistance to activation-induced apoptosis in murine Th1 cells following CD3 ligation, akin to what is observed in Th2 cells containing Cbl-b. Concurrent with the apoptosis profile, CD3 ligation in the absence of Cbl-b induced raft mobilization and cytoskeletal rearrangement in Th1 cells. Despite their ability to signal from CD3, Th2 cells did not aggregate their rafts, providing an explanation for cell-specific activity of Cbl-b.
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Affiliation(s)
- Allison Hanlon
- Temple University School of Medicine, Department of Microbiology and Immunology, Philadelphia, PA, USA
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20
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Switzer KC, McMurray DN, Chapkin RS. Effects of dietary n-3 polyunsaturated fatty acids on T-cell membrane composition and function. Lipids 2005; 39:1163-70. [PMID: 15736911 DOI: 10.1007/s11745-004-1343-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Dietary n-3 PUFA have been shown to attenuate T-cell-mediated inflammation, in part, by suppressing T-cell activation and proliferation. n-3 PUFA have also been shown to promote apoptosis, another important mechanism for the prevention of chronic inflammation by maintaining T-cell homeostasis through the contraction of populations of activated T cells. Recent studies have specifically examined Fas death receptor-mediated activation-induced cell death (AICD), since it is the form of apoptosis associated with peripheral T-cell deletion involved in immunological tolerance and T-cell homeostasis. Data from our laboratory indicate that n-3 PUFA promote AICD in T helper 1 polarized cells, which are the mediators of chronic inflammation. Since Fas and components of the death-inducing signaling complex are recruited to plasma membrane microdomains (rafts), the effect of dietary n-3 PUFA on raft composition and resident protein localization has been the focus of recent investigations. Indeed, there is now compelling evidence that dietary n-3 PUFA are capable of modifying the composition of T-cell membrane microdomains (rafts). Because the lipids found in membrane microdomains actively participate in signal transduction pathways, these results support the hypothesis that dietary n-3 PUFA influence signaling complexes and modulate T-cell cytokinetics in vivo by altering T-cell raft composition.
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Affiliation(s)
- Kirsten C Switzer
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University Health Science Center, College Station, Texas 77843-2471, USA
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21
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Razzaq TM, Ozegbe P, Jury EC, Sembi P, Blackwell NM, Kabouridis PS. Regulation of T-cell receptor signalling by membrane microdomains. Immunology 2004; 113:413-26. [PMID: 15554919 PMCID: PMC1782593 DOI: 10.1111/j.1365-2567.2004.01998.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2004] [Revised: 09/09/2004] [Accepted: 09/15/2004] [Indexed: 01/04/2023] Open
Abstract
There is now considerable evidence suggesting that the plasma membrane of mammalian cells is compartmentalized by functional lipid raft microdomains. These structures are assemblies of specialized lipids and proteins and have been implicated in diverse biological functions. Analysis of their protein content using proteomics and other methods revealed enrichment of signalling proteins, suggesting a role for these domains in intracellular signalling. In T lymphocytes, structure/function experiments and complementary pharmacological studies have shown that raft microdomains control the localization and function of proteins which are components of signalling pathways regulated by the T-cell antigen receptor (TCR). Based on these studies, a model for TCR phosphorylation in lipid rafts is presented. However, despite substantial progress in the field, critical questions remain. For example, it is unclear if membrane rafts represent a homogeneous population and if their structure is modified upon TCR stimulation. In the future, proteomics and the parallel development of complementary analytical methods will undoubtedly contribute in further delineating the role of lipid rafts in signal transduction mechanisms.
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Affiliation(s)
- Tahir M Razzaq
- Bone and Joint Research Unit, William Harvey Research Institute, Queen Mary's School of Medicine and Dentistry, Queen Mary's College, London
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22
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Fan YY, Ly LH, Barhoumi R, McMurray DN, Chapkin RS. Dietary Docosahexaenoic Acid Suppresses T Cell Protein Kinase Cθ Lipid Raft Recruitment and IL-2 Production. THE JOURNAL OF IMMUNOLOGY 2004; 173:6151-60. [PMID: 15528352 DOI: 10.4049/jimmunol.173.10.6151] [Citation(s) in RCA: 195] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To date, the proximal molecular targets through which dietary n-3 polyunsaturated fatty acids (PUFA) suppress the inflammatory process have not been elucidated. Because cholesterol and sphingolipid-enriched rafts have been proposed as platforms for compartmentalizing dynamically regulated signaling assemblies at the plasma membrane, we determined the in vivo effects of fish oil and highly purified docosahexaenoic acid (DHA; 22:6n-3) on T cell microdomain lipid composition and the membrane subdomain distribution of signal-transducing molecules (protein kinase C (PKC)theta;, linker for activation of T cells, and Fas/CD95), before and after stimulation. Mice were fed diets containing 5 g/100 g corn oil (control), 4 g/100 g fish oil (contains a mixture of n-3 PUFA) plus 1 g/100 g corn oil, or 4 g/100 g corn oil plus 1 g/100 g DHA ethyl ester for 14 days. Dietary n-3 PUFA were incorporated into splenic T cell lipid raft and soluble membrane phospholipids, resulting in a 30% reduction in raft sphingomyelin content. In addition, polyclonal activation-induced colocalization of PKCtheta; with lipid rafts was reduced by n-3 PUFA feeding. With respect to PKCtheta; effector pathway signaling, both AP-1 and NF-kappaB activation, IL-2 secretion, and lymphoproliferation were inhibited by fish oil feeding. Similar results were obtained when purified DHA was fed. These data demonstrate for the first time that dietary DHA alters T cell membrane microdomain composition and suppresses the PKCtheta; signaling axis.
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Affiliation(s)
- Yang-Yi Fan
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University Health Science Center, College Station, TX 77843-2471, USA
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23
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Geahlen RL, Handley MD, Harrison ML. Molecular interdiction of Src-family kinase signaling in hematopoietic cells. Oncogene 2004; 23:8024-32. [PMID: 15489920 DOI: 10.1038/sj.onc.1208078] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability of Src-family kinases (SFKs) to mediate signaling from cell surface receptors in hematopoietic cells is a function of their catalytic activity, location and binding partners. Kinase activity is regulated in the cell by kinases and phosphatases that alter the state of phosphorylation of key tyrosine residues and by protein binding partners that stabilize the kinase in active or inactive conformations or localize the enzyme to specific subcellular or submembrane domains. Kinase activity and function can be modulated experimentally through the use of small molecule inhibitors designed to directly target catalytic or binding domains or regulate the location of the protein by altering its state of acylation.
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Affiliation(s)
- Robert L Geahlen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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24
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Watson ARO, Lee WT. Differences in signaling molecule organization between naive and memory CD4+ T lymphocytes. THE JOURNAL OF IMMUNOLOGY 2004; 173:33-41. [PMID: 15210756 DOI: 10.4049/jimmunol.173.1.33] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The immunological synapse is a highly organized complex formed at the junction between Ag-specific T cells and APCs as a prelude to cell activation. Although its exact role in modulating T cell signaling is unknown, it is commonly believed that the immunological synapse is the site of cross-talk between the T cell and APC (or target). We have examined the synapses formed by naive and memory CD4 cells during Ag-specific cognate interactions with APCs. We show that the mature immunological synapse forms more quickly during memory T cell activation. We further show that the composition of the synapse found in naive or memory cell conjugates with APCs is distinct with the tyrosine phosphatase, CD45, being a more integral component of the mature synapses formed by memory cells. Finally, we show that signaling molecules, including CD45, are preassociated in discrete, lipid-raft microdomains in resting memory cells but not in naive cells. Thus, enhanced memory cell responses may be due to intrinsic properties of signaling molecule organization.
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Affiliation(s)
- Andrew R O Watson
- Department of Biomedical Sciences, School of Public Health, State University of New York, Albany, NY 12201-0509, USA
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25
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Moore DJ, Huang X, Lee MK, Lian MM, Chiaccio M, Chen H, Koeberlein B, Zhong R, Markmann JF, Deng S. Resistance to anti-CD45RB-induced tolerance in NOD mice: mechanisms involved. Transpl Int 2004. [DOI: 10.1111/j.1432-2277.2004.tb00440.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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26
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Switzer KC, Fan YY, Wang N, McMurray DN, Chapkin RS. Dietary n-3 polyunsaturated fatty acids promote activation-induced cell death in Th1-polarized murine CD4+ T-cells. J Lipid Res 2004; 45:1482-92. [PMID: 15145980 PMCID: PMC4469998 DOI: 10.1194/jlr.m400028-jlr200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Dietary n-3 PUFAs have been shown to attenuate T-cell-mediated inflammation. To investigate whether dietary n-3 PUFAs promote activation-induced cell death (AICD) in CD4+ T-cells induced in vitro to a polarized T-helper1 (Th1) phenotype, C57BL/6 mice were fed diets containing either 5% corn oil (CO; n-6 PUFA control) or 4% fish oil (FO) plus 1% CO (n-3 PUFA) for 2 weeks. Splenic CD4+ T-cells were cultured with alpha-interleukin-4 (alphaIL-4), IL-12, and IL-2 for 2 days and then with recombinant (r) IL-12 and rIL-2 for 3 days in the presence of diet-matched homologous mouse serum (HMS) to prevent loss of cell membrane fatty acids, or with fetal bovine serum. After polarization, Th1 cells were reactivated and analyzed for interferon-gamma and IL-4 by intracellular cytokine staining and for apoptosis by Annexin V/propidium iodide. Dietary FO enhanced Th1 polarization by 49% (P = 0.0001) and AICD by 24% (P = 0.0001) only in cells cultured in the presence of HMS. FO enhancement of Th1 polarization and AICD after culture was associated with the maintenance of eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3) in plasma membrane lipid rafts. In conclusion, n-3 PUFAs enhance the polarization and deletion of proinflammatory Th1 cells, possibly as a result of alterations in membrane microdomain fatty acid composition.
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Affiliation(s)
- Kirsten C. Switzer
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University, College Station, TX
| | - Yang-Yi Fan
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University, College Station, TX
| | - Naisyin Wang
- Department of Statistics, Texas A&M University, College Station, TX
| | - David N. McMurray
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University, College Station, TX
- Center for Environmental and Rural Health, Texas A&M University, College Station, TX
- Department of Microbiology and Immunology, Texas A&M University Health Science Center, College Station, TX
| | - Robert S. Chapkin
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University, College Station, TX
- Center for Environmental and Rural Health, Texas A&M University, College Station, TX
- To whom correspondence should be addressed.
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27
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Carpino N, Turner S, Mekala D, Takahashi Y, Zang H, Geiger TL, Doherty P, Ihle JN. Regulation of ZAP-70 activation and TCR signaling by two related proteins, Sts-1 and Sts-2. Immunity 2004; 20:37-46. [PMID: 14738763 DOI: 10.1016/s1074-7613(03)00351-0] [Citation(s) in RCA: 138] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
T cells play a central role in the recognition and elimination of foreign pathogens. Signals through the T cell receptor (TCR) control the extent and duration of the T cell response. To ensure that T cells are not inappropriately activated, signaling pathways downstream of the TCR are subject to multiple levels of positive and negative regulation. Herein, we describe two related proteins, Sts-1 and Sts-2, that negatively regulate TCR signaling. T cells from mice lacking Sts-1 and Sts-2 are hyperresponsive to TCR stimulation. The phenotype is accompanied by increased Zap-70 phosphorylation and activation, including its ubiquitinylated forms. Additionally, hyperactivation of signaling proteins downstream of the TCR, a marked increase in cytokine production by Sts1/2(-/-) T cells, and increased susceptibility to autoimmunity in a mouse model of multiple sclerosis is observed. Therefore, Sts-1 and Sts-2 are critical regulators of the signaling pathways that regulate T cell activation.
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Affiliation(s)
- Nick Carpino
- Department of Biochemistry, Saint Jude Children's Research Hospital, Memphis, TN 38105, USA
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28
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Abstract
In the last few years it has become clear that in cells of the immune system, specialized microdomains present in the plasma membrane, called lipid rafts, have been found to play a central role in regulating signalling by immune receptors. Recent studies have looked at whether lipid rafts may be connected to the abnormalities in signalling seen in T lymphocytes isolated from patients with systemic lupus erythematosus (SLE). These early findings show that in SLE T cells, the expression and protein composition of lipid rafts is different when compared with normal T cells. These results also demonstrate changes in the function and localization of critical signalling molecules such as the LCK tyrosine kinase and the CD45 tyrosine phosphatase.
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Affiliation(s)
- E C Jury
- Centre for Rheumatology, Royal Free and University College Medical School, London, UK.
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29
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Hare KJ, Pongracz J, Jenkinson EJ, Anderson G. Modeling TCR signaling complex formation in positive selection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:2825-31. [PMID: 12960303 DOI: 10.4049/jimmunol.171.6.2825] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T cell receptor signaling in the thymus can result in positive selection, and hence progressive maturation to the CD4(+)8(-) or CD4(-)8(+) stage, or induction of apoptosis by negative selection. Although it is poorly understood how TCR ligation at the CD4(+)8(+) stage can lead to such different cell fates, it is thought that the strength of signal may play a role in determining the outcome of TCR signaling. In this study, we have characterized the formation of an active signaling complex in thymocytes undergoing positive selection as a result of interaction with thymic epithelial cells. Although this signaling complex involves redistribution of cell surface and intracellular molecules, reminiscent of that observed in T cell activation, accumulation of GM1-containing lipid rafts was not observed. However, enforced expression of the costimulatory molecule CD80 on thymic epithelium induced GM1 polarization in thymocytes, and was accompanied by reduced positive selection and increased apoptosis. We suggest that the presence or absence of CD80 costimulation influences the outcome of TCR signaling in CD4(+)8(+) thymocytes through differential lipid raft recruitment, thus determining overall signal strength and influencing developmental cell fate.
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MESH Headings
- Animals
- Antigens, CD
- CD3 Complex/metabolism
- Cell Aggregation/genetics
- Cell Aggregation/immunology
- Cell Communication/genetics
- Cell Communication/immunology
- Cell Differentiation/genetics
- Cell Differentiation/immunology
- Cell Membrane/genetics
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cell Separation
- Epithelial Cells/cytology
- Epithelial Cells/immunology
- G(M1) Ganglioside/metabolism
- Intracellular Fluid/immunology
- Intracellular Fluid/metabolism
- Leukocyte Common Antigens/metabolism
- Leukosialin
- Major Histocompatibility Complex/physiology
- Membrane Microdomains/genetics
- Membrane Microdomains/immunology
- Membrane Microdomains/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Knockout
- Models, Immunological
- Organ Culture Techniques
- Receptors, Antigen, T-Cell, alpha-beta/deficiency
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/physiology
- Sialoglycoproteins/metabolism
- Signal Transduction/genetics
- Signal Transduction/immunology
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocyte Subsets/metabolism
- Thymus Gland/cytology
- Thymus Gland/immunology
- Thymus Gland/metabolism
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Affiliation(s)
- Katherine J Hare
- Department of Anatomy, Medical Research Council Centre for Immune Regulation, University of Birmingham, Birmingham, United Kingdom.
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30
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Dykstra M, Cherukuri A, Sohn HW, Tzeng SJ, Pierce SK. Location is everything: lipid rafts and immune cell signaling. Annu Rev Immunol 2003; 21:457-81. [PMID: 12615889 DOI: 10.1146/annurev.immunol.21.120601.141021] [Citation(s) in RCA: 373] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The cells of both the adaptive and innate immune systems express a dizzying array of receptors that transduce and integrate an enormous amount of information about the environment that allows the cells to mount effective immune responses. Over the past several years, significant advances have been made in elucidating the molecular details of signal cascades initiated by the engagement of immune cell receptors by their ligands. Recent evidence indicates that immune receptors and components of their signaling cascades are spatially organized and that this spatial organization plays a central role in the initiation and regulation of signaling. A key organizing element for signaling receptors appears to be cholesterol- and sphingolipid-rich plasma membrane microdomains termed lipid rafts. Research into the molecular basis of the spatial segregation and organization of signaling receptors provided by rafts is adding fundamentally to our understanding of the initiation and prolongation of signals in the immune system.
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Affiliation(s)
- Michelle Dykstra
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland 20852, USA.
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31
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Staffler G, Szekeres A, Schütz GJ, Säemann MD, Prager E, Zeyda M, Drbal K, Zlabinger GJ, Stulnig TM, Stockinger H. Selective inhibition of T cell activation via CD147 through novel modulation of lipid rafts. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2003; 171:1707-14. [PMID: 12902469 DOI: 10.4049/jimmunol.171.4.1707] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The plasma membrane is compartmentalized into microdomains and the association/dissociation of receptors and signaling molecules with/from these membrane domains is a major principle for regulation of signal transduction. By following the reorganization of microdomains on living cells and performing biochemical studies, we show that Ab targeting of the T cell activation-associated Ag CD147 prevents TCR stimulation-dependent reorganization and clustering of microdomains. Triggering CD147 induces a displacement of the GPI-anchored coreceptors CD48 and CD59 from microdomains in human T lymphocytes. This perturbation of microdomains is accompanied by a selective inhibition of TCR-mediated T cell proliferation. The CD147-inhibited cells secret normal levels of IL-2 but acquire reduced amounts of the IL-2 receptor alpha-chain CD25. These results indicate that negative regulating signals can modulate microdomains and suggest a general mechanism for inhibition of receptor signaling.
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MESH Headings
- Antibodies, Monoclonal/pharmacology
- Antigens, CD
- Antigens, Neoplasm
- Antigens, Surface
- Avian Proteins
- Basigin
- Blood Proteins
- CD28 Antigens/immunology
- CD28 Antigens/physiology
- Cell Division/immunology
- Cell Separation
- Cells, Cultured
- Cytokines/genetics
- Cytokines/metabolism
- Down-Regulation/immunology
- Humans
- Immunologic Capping/immunology
- Interleukin-2/antagonists & inhibitors
- Interleukin-2/metabolism
- Isoantigens/physiology
- Lymphocyte Activation/immunology
- Lymphocyte Culture Test, Mixed
- Membrane Glycoproteins/immunology
- Membrane Glycoproteins/physiology
- Membrane Microdomains/immunology
- Membrane Microdomains/metabolism
- Membrane Microdomains/physiology
- Muromonab-CD3/pharmacology
- Phosphorylation
- Phosphotyrosine/metabolism
- Receptor-CD3 Complex, Antigen, T-Cell/antagonists & inhibitors
- Receptor-CD3 Complex, Antigen, T-Cell/immunology
- Receptor-CD3 Complex, Antigen, T-Cell/physiology
- Receptors, Cytokine/genetics
- Receptors, Cytokine/metabolism
- Signal Transduction/immunology
- T-Lymphocytes/immunology
- T-Lymphocytes/metabolism
- Transcription, Genetic/immunology
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32
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Woods CC, Banks KE, Gruener R, DeLuca D. Loss of T cell precursors after spaceflight and exposure to vector-averaged gravity. FASEB J 2003; 17:1526-8. [PMID: 12824295 DOI: 10.1096/fj.02-0749fje] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Using fetal thymus organ culture (FTOC), we examined the effects of spaceflight and vector-averaged gravity on T cell development. Under both conditions, the development of T cells was significantly attenuated. Exposure to spaceflight for 16 days resulted in a loss of precursors for CD4+, CD8+, and CD4+CD8+ T cells in a rat/mouse xenogeneic co-culture. A significant decrease in the same precursor cells, as well as a decrease in CD4-CD8- T cell precursors, was also observed in a murine C57BL/6 FTOC after rotation in a clinostat to produce a vector-averaged microgravity-like environment. The block in T cell development appeared to occur between the pre-T cell and CD4+CD8+ T cell stage. These data indicate that gravity plays a decisive role in the development of T cells.
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Affiliation(s)
- Chris C Woods
- Department of Microbiology and Immunology, University of Arizona, Tucson, Arizona 85724, USA
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33
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Fan YY, McMurray DN, Ly LH, Chapkin RS. Dietary (n-3) polyunsaturated fatty acids remodel mouse T-cell lipid rafts. J Nutr 2003; 133:1913-20. [PMID: 12771339 DOI: 10.1093/jn/133.6.1913] [Citation(s) in RCA: 178] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In vitro evidence indicates that (n-3) polyunsaturated fatty acids (PUFA) suppress T-cell activation in part by displacing proteins from lipid rafts, specialized regions within the plasma membrane that play an important role in T-cell signal transduction. However, the ability of (n-3) PUFA to influence membrane microdomains in vivo has not been examined to date. Therefore, we compared the effect of dietary (n-3) PUFA on raft (liquid ordered) vs. soluble (liquid disordered) microdomain phospholipid composition in mouse T cells. Mice were fed diets containing either 5 g/100 g corn oil (control) or 4 g/100 g fish oil [contains (n-3) PUFA] + 1 g/100 g corn oil for 14 d. Splenic T-cell lipid rafts were isolated by density gradient centrifugation. Raft sphingomyelin content (mol/100 mol) was decreased (P < 0.05) in T cells isolated from (n-3) PUFA-fed mice. Dietary (n-3) PUFA were selectively incorporated into T-cell raft and soluble membrane phospholipids. Phosphatidylserine and glycerophosphoethanolamine, which are highly localized to the inner cytoplasmic leaflet, were enriched to a greater extent with unsaturated fatty acids compared with sphingomyelin, phosphatidylinositol and glycerophosphocholine. These data indicate for the first time that dietary (n-3) PUFA differentially modulate T-cell raft and soluble membrane phospholipid and fatty acyl composition.
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Affiliation(s)
- Yang-Yi Fan
- Faculty of Nutrition, Center for Environmental and Rural Health, Texas A&M University System, Health Science Center, College Station, TX, USA
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34
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Jury EC, Kabouridis PS, Abba A, Mageed RA, Isenberg DA. Increased ubiquitination and reduced expression of LCK in T lymphocytes from patients with systemic lupus erythematosus. ARTHRITIS AND RHEUMATISM 2003; 48:1343-54. [PMID: 12746907 DOI: 10.1002/art.10978] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
OBJECTIVE To explore regulation of proximal signaling and composition of lipid rafts in T lymphocytes from patients with systemic lupus erythematosus (SLE). METHODS The expression, phosphorylation, and degradation of lipid raft-associated signaling molecules in T lymphocytes from 50 patients with SLE compared with 28 healthy controls and 22 rheumatoid arthritis patients were investigated. Lipid raft and nonraft fractions from T cells were isolated by ultracentrifugation. Proteins in the lipid raft and nonraft fractions were analyzed by Western blotting and probed for phosphotyrosine activity and for LCK, LAT, and CD3 epsilon. Immunoprecipitation experiments were performed to assess protein ubiquitination in T cell lysates. T cell phenotype and levels of intracellular LCK were determined by flow cytometry. RESULTS LCK, an essential signaling molecule for T cell activation, was significantly reduced in both lipid raft and nonraft fractions of T lymphocytes from patients with active SLE compared with controls, and the reduction was independent of treatment. To identify the likely causes of reduced LCK, we explored the possibility that chronic activation of T lymphocytes underlies LCK degradation. The results revealed an increase in protein ubiquitination, and specifically LCK ubiquitination, in T cells from SLE patients. However, our findings suggest that the increase in ubiquitination is independent of T cell activation. CONCLUSION LCK is reduced in T cell lipid rafts from patients with SLE. This reduction appears to be independent of activation and may be associated with abnormal ubiquitin-mediated regulation mechanisms.
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Affiliation(s)
- Elizabeth C Jury
- Royal Free and University College Medical School, University College, London, UK.
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35
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Abstract
There is abundant information on the distinguishing features of TCR-mediated signaling in Th1 and Th2 cells. However, the primary signals that determine the commitment and differentiation of naive T cells toward those T helper subsets, especially prior to the contribution of polarizing cytokines, remain elusive. This minireview discusses the potential contribution of SLAT in favoring differentiation along the Th2 lineage and how this may bring us closer to a framework model for Th1/Th2 differentiation.
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Affiliation(s)
- Joaquín Madrenas
- The Robarts Research Institute, The University of Western Ontario, London, Canada N6A 5K8.
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36
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Uhlin M, Masucci MG, Levitsky V. Pharmacological disintegration of lipid rafts decreases specific tetramer binding and disrupts the CD3 complex and CD8 heterodimer in human cytotoxic T lymphocytes. Scand J Immunol 2003; 57:99-106. [PMID: 12588655 DOI: 10.1046/j.1365-3083.2003.01188.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Accumulating evidence strongly supports the role of lipid rafts in the regulation of T-lymphocyte activation, but the organization and molecular composition of these cholesterol- and sphingolipid-rich membrane microdomains in different subsets of T cells remain poorly investigated. Here, we show that pharmacological disruption of lipid rafts in human CD8+ cytotoxic T-lymphocyte (CTL) clones disturbs the integrity of CD3 complex and CD8 heterodimer, without affecting the reactivity with T-cell receptor (TCR)-specific antibodies. This demonstrates that interaction with completely assembled CD3 complex is not required for the stable expression of TCR at the cell surface. The effect of raft disruption on CD3 and CD8 expression correlates with failure to bind specific tetrameric complexes by a proportion of surface TCR molecules. However, the interaction of specific tetramer with the rest of surface TCR pools appears to be unaffected, demonstrating that TCR-signalling complexes may differ in their requirement for cholesterol to stably maintain their composition and to rearrange for efficient tetramer binding. Together with previously published data, our results support the existence of molecular and/or structural heterogeneity of lipid rafts that may play an important role in controlling distinct functional properties of T-cell subsets.
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Affiliation(s)
- M Uhlin
- Microbiology and Tumorbiology Center, Karolinska Institutet, Stockholm, Sweden
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37
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Abstract
Detergent-resistant membrane microdomains enriched in sphingolipids, cholesterol and glycosylphosphatidylinositol-anchored proteins play essential roles in T cell receptor (TCR) signaling. These 'membrane rafts' accumulate several cytoplasmic lipid-modified molecules, including Src-family kinases, coreceptors CD4 and CD8 and transmembrane adapters LAT and PAG/Cbp, essential for either initiation or amplification of the signaling process, while most other abundant transmembrane proteins are excluded from these structures. TCRs in various T cell subpopulations may differ in their use of membrane rafts. Membrane rafts also seem to be involved in many other aspects of T cell biology, such as functioning of cytokine and chemokine receptors, adhesion molecules, antigen presentation, establishing cell polarity or interaction with important pathogens. Although the concept of membrane rafts explains several diverse biological phenomena, many basic issues, such as composition, size and heterogeneity, under native conditions, as well as the dynamics of their interactions with TCRs and other immunoreceptors, remain unclear, partially because of technical problems.
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Affiliation(s)
- Václav Horejsí
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Praha, Czech Republic.
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38
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Switzer KC, McMurray DN, Morris JS, Chapkin RS. (n-3) Polyunsaturated fatty acids promote activation-induced cell death in murine T lymphocytes. J Nutr 2003; 133:496-503. [PMID: 12566490 DOI: 10.1093/jn/133.2.496] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Previous studies showing dietary (n-3) polyunsaturated fatty acids (PUFA) attenuate T cell immune-mediated inflammatory diseases led us to hypothesize that (n-3) PUFA promote activation-induced cell death (AICD) in T cells. Because T cell subsets display a differential resistance to AICD, we compared the effects of (n-3) PUFA feeding on T cells stimulated in vitro to express different cytokine profiles. Mice were fed either diets lacking (n-3) PUFA (control) or (n-3) PUFA-containing diets for 14 d. Splenic T cells were stimulated with alphaCD3/alphaCD28, phorbol myristate acetate (PMA)/Ionomycin or alphaCD3/PMA for 48 h, followed by reactivation with the same stimuli for 5 h. Apoptosis was measured using Annexin V/propidium iodide. (n-3) PUFA were selectively incorporated into membrane phospholipid pools. Cytokine analyses revealed that (n-3) PUFA enhanced AICD only in T cells expressing a T helper cell (Th)1-like cytokine profile after stimulation with PMA/Ionomycin compared to mice fed the (n-6) PUFA control diet (P = 0.0008). In contrast, no increase in apoptosis was seen in T cells stimulated with alphaCD3/PMA, which exhibited a Th2 cytokine profile. These data demonstrate that the ability of (n-3) PUFA to promote AICD is dependent on the activation stimulus. In conclusion, we have identified a novel mechanism by which (n-3) PUFA modulate T cell-mediated immunity by selective deletion of Th1-like cells while maintaining or enhancing the Th2-mediated humoral immune response.
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Affiliation(s)
- Kirsten C Switzer
- Molecular and Cell Biology Section, Faculty of Nutrition, Texas A&M University, College Station, TX, USA
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39
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Wu L, Yu Z, Shen SH. SKAP55 recruits to lipid rafts and positively mediates the MAPK pathway upon T cell receptor activation. J Biol Chem 2002; 277:40420-7. [PMID: 12171928 DOI: 10.1074/jbc.m206023200] [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: 11/06/2022] Open
Abstract
T cell receptor (TCR) engagement triggers a series of events including protein tyrosine kinase activation, tyrosine phosphorylation of adapter proteins, and multiple protein-protein interactions. We observed that adapter protein SKAP55, the Src kinase-associated phosphoprotein, formed homodimers through its SH3 domain and SK region. SKAP55 as a substrate interacted with Fyn kinase in vivo. In Jurkat cells, interaction between SKAP55 and Fyn kinase depended on TCR activation. Stable overexpression of SKAP55 in Jurkat cells caused mitogen-activated protein kinase activation following TCR engagement. Anti-CD3 stimulation also promoted the interaction of SKAP55 with Grb-2 in T cells. Mutational analysis revealed that tyrosine 271 in SKAP55 played a pivotal role for interaction with both Fyn kinase and adapter protein Grb-2, indicating that the Fyn-phosphorylated SKAP55 transiently associates with adapter Grb-2 to mediate mitogen-activated protein kinase activation. Intriguingly, T cell receptor engagement dramatically induced the translocation of endogenous SKAP55 to lipid rafts where SKAP55 was found to interact with Fyn kinase, suggesting that the positive function of SKAP55 via its association with Fyn and other signaling components may have been involved in raft-mediated T cell activation.
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Affiliation(s)
- Liangtang Wu
- Mammalian Cell Genetics, Biotechnology Research Institute, National Research Council Canada, 6100 Royalmount Avenue, Montreal, Quebec H4P 2R2, Canada
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40
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Pradhan D, Morrow J. The spectrin-ankyrin skeleton controls CD45 surface display and interleukin-2 production. Immunity 2002; 17:303-15. [PMID: 12354383 DOI: 10.1016/s1074-7613(02)00396-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
With T cell receptor stimulation, intracellular pools of CD45 and spectrin move to the surface. These processes are coupled. In both peripheral lymphocytes and Jurkat T cells, betaI spectrin and ankyrin associate with CD45. In Jurkat T cells, betaI spectrin peptides suppress surface recruitment of CD45 and CD3 and abrogate T cell activation. Other glycoproteins such as CD43 are not altered by the spectrin peptides. Spectrin's effects are mediated by ankyrin, which binds directly to the cytoplasmic domain of CD45 (K(d) = 4.3 +/- 3.0 nM). These data reveal a novel and unexpected contribution of the spectrin-ankyrin skeleton to the control of T lymphocyte function.
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Affiliation(s)
- Deepti Pradhan
- Department of Pathology, Yale University, 310 Cedar Street, New Haven, CT 06510, USA
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41
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Zeyda M, Staffler G, Horejsi V, Waldhausl W, Stulnig TM. LAT displacement from lipid rafts as a molecular mechanism for the inhibition of T cell signaling by polyunsaturated fatty acids. J Biol Chem 2002; 277:28418-23. [PMID: 12029091 DOI: 10.1074/jbc.m203343200] [Citation(s) in RCA: 123] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Polyunsaturated fatty acids (PUFAs) suppress immune responses and inhibit T cell activation through largely unknown mechanisms. The displacement of signaling proteins from membrane lipid rafts has recently been suggested as underlying PUFA-mediated T cell inhibition. We show here that PUFA treatment specifically interferes with T cell signal transduction by blocking tyrosine phosphorylation of LAT (linker for activation of T cells) and phospholipase Cgamma1. A significant fraction of LAT was displaced from rafts by PUFA treatment along with other signaling proteins. However, retaining LAT alone in lipid rafts effectively restored phospholipase Cgamma1/calcium signaling in PUFA-treated T cells. These data reveal LAT displacement from lipid rafts as a molecular mechanism by which PUFAs inhibit T cell signaling and underline the predominant importance of LAT localization in rafts for efficient T cell activation.
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Affiliation(s)
- Maximilian Zeyda
- Department of Internal Medicine III and the Institute of Immunology, University of Vienna, A-1090 Vienna, Austria
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42
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Werlen G, Palmer E. The T-cell receptor signalosome: a dynamic structure with expanding complexity. Curr Opin Immunol 2002; 14:299-305. [PMID: 11973126 DOI: 10.1016/s0952-7915(02)00339-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Signal transduction in T cells is a dynamic process involving a large number of membrane and cytosolic proteins. The TCR macromolecular complex (signalosome) is initiated by receptor occupancy and becomes more elaborate over time. This review describes how 'vertical' displacement mechanisms and lateral coalescence of lipid-raft-associated scaffold proteins combine to form distinct signalosomes, which control signal specificity.
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Affiliation(s)
- Guy Werlen
- Laboratory of Transplantation Immunology and Nephrology, Department of Research, University Hospital-Basel, Hebelstrasse 20, CH-4031, Basel, Switzerland.
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43
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Nel AE, Slaughter N. T-cell activation through the antigen receptor. Part 2: role of signaling cascades in T-cell differentiation, anergy, immune senescence, and development of immunotherapy. J Allergy Clin Immunol 2002; 109:901-15. [PMID: 12063516 DOI: 10.1067/mai.2002.124965] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Part 2 of this review on cellular activation by the T-cell antigen receptor (TCR) will highlight how TCR signaling pathways are adapted to achieve specific biologic outcomes, including different states of T-cell differentiation and the induction of T-cell tolerance. We will also explore how treatment with altered peptide ligands affects TCR signaling to change T-cell differentiation or to induce an anergy state. These changes are accomplished through alteration of protein tyrosine kinase activity, the stoichiometry of phosphorylation of immunoreceptor tyrosine-based activation motifs, intracellular free ionized calcium flux, mitogen-activated protein kinase activity, and transcriptional activation of key cytokine promoters. The CTLA-4 plays an important role in the induction and maintenance of anergy. The second theme will highlight how altered TCR signal transduction, including changes in the compartmentalization of signaling components at the TCR synapse, contributes to decreased T-cell activation during immune senescence. Finally, we will illustrate how the molecular details of TCR activation can be used to modify the function of the immune system. This includes a description of the mechanism of action of altered peptide ligands, CTLA-4Ig, and pharmacologic inhibitors of mitogen-activated protein kinases, nuclear factor kappaB, and protein kinase C cascades.
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Affiliation(s)
- Andre E Nel
- Division of Clinical Immunology/Allergy, Department of Medicine, UCLA School of Medicine, University of California, Los Angeles 90095-1680, USA
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44
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Nel AE. T-cell activation through the antigen receptor. Part 1: signaling components, signaling pathways, and signal integration at the T-cell antigen receptor synapse. J Allergy Clin Immunol 2002; 109:758-70. [PMID: 11994696 DOI: 10.1067/mai.2002.124259] [Citation(s) in RCA: 134] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Part 1 of this review will highlight the basic components and signaling pathways by which the T-cell antigen receptor (TCR) activates mature extrathymic T cells. TCR signaling commences with an early wave of protein tyrosine kinase activation, which is mediated by the Src kinases Lck and Fyn, the 70-kd zeta-associated protein kinase, and members of the Tec kinase family. This early wave of protein tyrosine phosphorylation leads to the activation of downstream signaling pathways, including an increase in intracellular free calcium, protein kinase C, nuclear factor kappaB and Ras-mitogen-activated protein kinase activation. These pathways activate transcription factors, such as activator protein 1, nuclear factor of activated T cells, and Rel proteins, which ultimately lead to the expression of genes that control cellular proliferation, differentiation, anergy, or apoptosis. This review also describes how costimulatory receptors assist in signal transduction and assembly of macromolecular complexes at the TCR contact site with the antigen-presenting cell, also known as the immune synapse. These basic concepts of TCR signal transduction will be used in part 2 to explain how T-cell function can be altered by therapeutic targeting of TCR signaling components, as well as to explain modification of TCR signaling during T(H)1/T(H)2 differentiation, tolerance, and immune senescence.
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Affiliation(s)
- Andre E Nel
- Division of Clinical Immunology/Allergy, Department of Medicine, UCLA School of Medicine, University of California, Los Angeles 90095-1680, USA
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45
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Hawash IY, Hu XE, Adal A, Cassady JM, Geahlen RL, Harrison ML. The oxygen-substituted palmitic acid analogue, 13-oxypalmitic acid, inhibits Lck localization to lipid rafts and T cell signaling. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1589:140-50. [PMID: 12007789 DOI: 10.1016/s0167-4889(02)00165-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Palmitoylation of cysteines 3 and 5 is necessary for targeting Lck to lipid rafts and is needed for Lck function in T cell receptor (TCR) signaling. Point mutations of cysteines 3 and 5 result in a form of Lck that fails to associate with the plasma membrane, which limits the usefulness of this genetic approach to address the role of palmitoylation in the distribution of Lck within the plasma membrane. To circumvent this problem, we sought to identify a palmitic acid analogue that would enable plasma membrane association of Lck, but not facilitate its localization within lipid rafts. Here we examined the effects of the heteroatom-substituted analogue of palmitic acid, 13-oxypalmitic acid (13-OP), on Lck subcellular localization and function. 13-OP is similar in chain length to palmitic acid, but possesses reduced hydrophobicity. We found that treatment of cells with 13-OP inhibited incorporation of omega-[(125)I]iodopalmitate into Lck. 13-OP inhibited localization of Lck to lipid rafts without altering its membrane localization. Consistent with the dissociation of Lck from rafts, treatment with 13-OP abolished Lck association with the GPI-anchored protein, CD48, but not the transmembrane glycoprotein CD4. Jurkat T cells treated with 13-OP showed marked reduction in tyrosine phosphorylation and activation of mitogen-activated protein kinase upon TCR stimulation. In conclusion, the less hydrophobic analogue of palmitate, 13-OP, alters the normal acylation of Lck that provides Lck with the necessary hydrophobicity and tight packing order required for inclusion in lipid rafts.
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Affiliation(s)
- Ibrahim Y Hawash
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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46
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Schade AE, Levine AD. Lipid raft heterogeneity in human peripheral blood T lymphoblasts: a mechanism for regulating the initiation of TCR signal transduction. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:2233-9. [PMID: 11859110 DOI: 10.4049/jimmunol.168.5.2233] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Lateral mobility and spatial organization of proteins within the plasma membrane are likely to mediate the initial events coordinating T cell activation. Lipid rafts, distinct cholesterol/sphingolipid-rich membrane microdomains, provide a mechanism for this regulation by concentrating or excluding signaling proteins. We demonstrate in peripheral blood T cell lymphoblasts that immediate early phosphotyrosine signal transduction through the TCR complex is functionally dependent on a distinct population of lipid rafts. Specifically, cholesterol extraction destabilizes the membrane microdomains containing Lck, while the rafts containing the adapter protein linker for activation of T cells remain intact. Heterogeneity in the partitioning of these proteins in resting cells was confirmed by immunoelectron microscopy. After T cell activation, both Lck and the linker for activation of T cells colocalize to 50-100 nm microdomains in the plasma membrane, indicating that sequestration of these proteins into distinct lipid rafts may function to regulate the initiation of T cell signal transduction.
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Affiliation(s)
- Andrew E Schade
- Department of Pathology, Case Western Reserve University School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
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47
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Zajchowski LD, Robbins SM. Lipid rafts and little caves. Compartmentalized signalling in membrane microdomains. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:737-52. [PMID: 11846775 DOI: 10.1046/j.0014-2956.2001.02715.x] [Citation(s) in RCA: 197] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Lipid rafts are liquid-ordered membrane microdomains with a unique protein and lipid composition found on the plasma membrane of most, if not all, mammalian cells. A large number of signalling molecules are concentrated within rafts, which have been proposed to function as signalling centres capable of facilitating efficient and specific signal transduction. This review summarizes current knowledge regarding the composition, structure, and dynamic nature of lipid rafts, as well as a number of different signalling pathways that are compartmentalized within these microdomains. Potential mechanisms through which lipid rafts carry out their specialized role in signalling are discussed in light of recent experimental evidence.
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48
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Soldevila G, Castellanos C, Malissen M, Berg LJ. Analysis of the individual role of the TCRzeta chain in transgenic mice after conditional activation with chemical inducers of dimerization. Cell Immunol 2001; 214:123-38. [PMID: 12088411 DOI: 10.1006/cimm.2001.1892] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Signaling through the TCR/CD3 complex plays a critical role in T-cell development and activation. Gene-targeted mice lacking particular components of this complex show arrested T-cell development in the thymus. As all TCR/CD3 components are required for efficient surface expression of the complex, it is difficult to assess the specific signaling role of each receptor component. To overcome this problem, we designed a strategy to examine the specific role(s) of individual receptor chains. A chimeric protein, containing binding domains for chemical inducers of dimerization fused to the cytoplasmic tail of TCRzeta, was generated. Activation of the chimeric receptor after stimulation with chemical dimerizers in Jurkat cells showed tyrosine phosphorylation of the TCRzeta chain chimera, recruitment of phosphorylated Zap70, and generation of NFAT in a reporter assay. Analysis of thymocytes from transgenic mice expressing this chimeric receptor showed that intracytoplasmic crosslinking of the chimera induced tyrosine phosphorylation of the protein, as well as a slow and very weak calcium mobilization response. However, this signaling did not lead to increased expression of activation markers, T-cell proliferation, or apoptosis. In addition, stimulation of thymocytes in suspension or in fetal thymic organ cultures with chemical inducers of dimerization did not lead to alterations in positive or negative selection. We conclude that signaling through the TCRzeta chain alone is not sufficient to generate downstream events leading to full T-cell activation or thymocyte selection; instead, additional CD3 components must be required to induce a functional response in primary thymocytes and peripheral T cells.
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Affiliation(s)
- G Soldevila
- Departamento de Inmunología, Universidad Nacional Autónoma de México, México DF, México.
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49
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Dykstra M, Cherukuri A, Pierce SK. Rafts and synapses in the spatial organization of immune cell signaling receptors. J Leukoc Biol 2001. [DOI: 10.1189/jlb.70.5.699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Michelle Dykstra
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Anu Cherukuri
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Susan K. Pierce
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
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