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Xie X, Mahmood SR, Gjorgjieva T, Percipalle P. Emerging roles of cytoskeletal proteins in regulating gene expression and genome organization during differentiation. Nucleus 2020; 11:53-65. [PMID: 32212905 PMCID: PMC7289583 DOI: 10.1080/19491034.2020.1742066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the eukaryotic cell nucleus, cytoskeletal proteins are emerging as essential players in nuclear function. In particular, actin regulates chromatin as part of ATP-dependent chromatin remodeling complexes, it modulates transcription and it is incorporated into nascent ribonucleoprotein complexes, accompanying them from the site of transcription to polyribosomes. The nuclear actin pool is undistinguishable from the cytoplasmic one in terms of its ability to undergo polymerization and it has also been implicated in the dynamics of chromatin, regulating heterochromatin segregation at the nuclear lamina and maintaining heterochromatin levels in the nuclear interiors. One of the next frontiers is, therefore, to determine a possible involvement of nuclear actin in the functional architecture of the cell nucleus by regulating the hierarchical organization of chromatin and, thus, genome organization. Here, we discuss the repertoire of these potential actin functions and how they are likely to play a role in the context of cellular differentiation.
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Affiliation(s)
- Xin Xie
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates
| | - S Raza Mahmood
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates.,Department of Biology, New York University, New York, NY, USA
| | - Tamara Gjorgjieva
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates
| | - Piergiorgio Percipalle
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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2
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Aramesh M, Stoycheva D, Raaz L, Klotzsch E. Engineering T-cell activation for immunotherapy by mechanical forces. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2019. [DOI: 10.1016/j.cobme.2019.05.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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3
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Parween F, Yadav J, Qadri A. The Virulence Polysaccharide of Salmonella Typhi Suppresses Activation of Rho Family GTPases to Limit Inflammatory Responses From Epithelial Cells. Front Cell Infect Microbiol 2019; 9:141. [PMID: 31134159 PMCID: PMC6517557 DOI: 10.3389/fcimb.2019.00141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/16/2019] [Indexed: 12/20/2022] Open
Abstract
Vi capsular polysaccharide (Vi) is a major virulence factor of human typhoid-causing pathogen Salmonella enterica serovar Typhi (S. Typhi). It distinguishes S. Typhi from closely related non-typhoidal Salmonella serovars such as S. Typhimurium which do not normally cause systemic infection in humans. Vi not only forms a capsule around S. Typhi but it is also readily released from this pathogen. We have previously reported that Vi targets prohibitin to inhibit cellular responses activated through immune receptors. Here, we show that engagement of membrane prohibitin with Vi prevents Salmonella-induced activation of small Rho-family GTPases, Rac1, and Cdc42, and suppresses actin cytoskeletal rearrangements resulting in reduced invasion and highly subdued inflammatory responses. Cells infected with S. Typhimurium in the presence of Vi show poor activation of NF-kB and MAP-kinase pathways of intracellular signaling. Treatment with Vi brings about redistribution of Rac-1, prohibitin, and ganglioside GM1 in membrane raft domains. Vi-mediated interference with activation of Rho-family GTPases represents a previously unrecognized mechanism by which S. Typhi can limit its invasion and alarming of the host.
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Affiliation(s)
- Farhat Parween
- Hybridoma Laboratory, National Institute of Immunology, New Delhi, India
| | - Jitender Yadav
- Hybridoma Laboratory, National Institute of Immunology, New Delhi, India
| | - Ayub Qadri
- Hybridoma Laboratory, National Institute of Immunology, New Delhi, India
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4
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Delcassian D, Sattler S, Dunlop IE. T cell immunoengineering with advanced biomaterials. Integr Biol (Camb) 2017; 9:211-222. [PMID: 28252135 PMCID: PMC6034443 DOI: 10.1039/c6ib00233a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2016] [Accepted: 02/15/2017] [Indexed: 12/25/2022]
Abstract
Recent advances in biomaterials design offer the potential to actively control immune cell activation and behaviour. Many human diseases, such as infections, cancer, and autoimmune disorders, are partly mediated by inappropriate or insufficient activation of the immune system. T cells play a central role in the host immune response to these diseases, and so constitute a promising cell type for manipulation. In vivo, T cells are stimulated by antigen presenting cells (APC), therefore to design immunoengineering biomaterials that control T cell behaviour, artificial interfaces that mimic the natural APC-T cell interaction are required. This review draws together research in the design and fabrication of such biomaterial interfaces, and highlights efforts to elucidate key parameters in T cell activation, such as substrate mechanical properties and spatial organization of receptors, illustrating how they can be manipulated by bioengineering approaches to alter T cell function.
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Affiliation(s)
- Derfogail Delcassian
- School of Pharmacy, University of Nottingham, NG7 2RD, UK. and Koch Institute for Integrative Cancer Research, MIT, Massachusetts, 02139, USA
| | - Susanne Sattler
- Imperial College London National Heart and Lung Institute, Du Cane Road, W12 0NN, London, UK
| | - Iain E Dunlop
- Department of Materials, Imperial College London, SW7 2AZ, UK.
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Colin A, Bonnemay L, Gayrard C, Gautier J, Gueroui Z. Triggering signaling pathways using F-actin self-organization. Sci Rep 2016; 6:34657. [PMID: 27698406 PMCID: PMC5048156 DOI: 10.1038/srep34657] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 09/16/2016] [Indexed: 12/20/2022] Open
Abstract
The spatiotemporal organization of proteins within cells is essential for cell fate behavior. Although it is known that the cytoskeleton is vital for numerous cellular functions, it remains unclear how cytoskeletal activity can shape and control signaling pathways in space and time throughout the cell cytoplasm. Here we show that F-actin self-organization can trigger signaling pathways by engineering two novel properties of the microfilament self-organization: (1) the confinement of signaling proteins and (2) their scaffolding along actin polymers. Using in vitro reconstitutions of cellular functions, we found that both the confinement of nanoparticle-based signaling platforms powered by F-actin contractility and the scaffolding of engineered signaling proteins along actin microfilaments can drive a signaling switch. Using Ran-dependent microtubule nucleation, we found that F-actin dynamics promotes the robust assembly of microtubules. Our in vitro assay is a first step towards the development of novel bottom-up strategies to decipher the interplay between cytoskeleton spatial organization and signaling pathway activity.
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Affiliation(s)
- A. Colin
- Ecole Normale Supérieure, Department of Chemistry PSL Research University-CNRS-ENS-UPMC 24, rue Lhomond, 75005, Paris, France
| | - L. Bonnemay
- Ecole Normale Supérieure, Department of Chemistry PSL Research University-CNRS-ENS-UPMC 24, rue Lhomond, 75005, Paris, France
| | - C. Gayrard
- Ecole Normale Supérieure, Department of Chemistry PSL Research University-CNRS-ENS-UPMC 24, rue Lhomond, 75005, Paris, France
| | - J. Gautier
- Ecole Normale Supérieure, Department of Chemistry PSL Research University-CNRS-ENS-UPMC 24, rue Lhomond, 75005, Paris, France
| | - Z. Gueroui
- Ecole Normale Supérieure, Department of Chemistry PSL Research University-CNRS-ENS-UPMC 24, rue Lhomond, 75005, Paris, France
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Integration of proteomic and transcriptomic profiles identifies a novel PDGF-MYC network in human smooth muscle cells. Cell Commun Signal 2014; 12:44. [PMID: 25080971 PMCID: PMC4422302 DOI: 10.1186/s12964-014-0044-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 06/23/2014] [Indexed: 12/12/2022] Open
Abstract
Background Platelet-derived growth factor-BB (PDGF-BB) has been implicated in the proliferation, migration and synthetic activities of smooth muscle cells that characterize physiologic and pathologic tissue remodeling in hollow organs. However, neither the molecular basis of PDGFR-regulated signaling webs, nor the extent to which specific components within these networks could be exploited for therapeutic benefit has been fully elucidated. Results Expression profiling and quantitative proteomics analysis of PDGF-treated primary human bladder smooth muscle cells identified 1,695 genes and 241 proteins as differentially expressed versus non-treated cells. Analysis of gene expression data revealed MYC, JUN, EGR1, MYB, RUNX1, as the transcription factors most significantly networked with up-regulated genes. Forty targets were significantly altered at both the mRNA and protein levels. Proliferation, migration and angiogenesis were the biological processes most significantly associated with this signature, and MYC was the most highly networked master regulator. Alterations in master regulators and gene targets were validated in PDGF-stimulated smooth muscle cells in vitro and in a model of bladder injury in vivo. Pharmacologic inhibition of MYC and JUN confirmed their role in SMC proliferation and migration. Network analysis identified the diaphanous-related formin 3 as a novel PDGF target regulated by MYC and JUN, which was necessary for PDGF-stimulated lamellipodium formation. Conclusions These findings provide the first systems-level analysis of the PDGF-regulated transcriptome and proteome in normal smooth muscle cells. The analyses revealed an extensive cohort of PDGF-dependent biological processes and connected key transcriptional effectors to their regulation, significantly expanding current knowledge of PDGF-stimulated signaling cascades. These observations also implicate MYC as a novel target for pharmacological intervention in fibroproliferative expansion of smooth muscle, and potentially in cancers in which PDGFR-dependent signaling or MYC activation promote tumor progression.
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Demchenko AP. Modern views on the structure and dynamics of biological membranes. ACTA ACUST UNITED AC 2012. [DOI: 10.7124/bc.000029] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- A. P. Demchenko
- Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine
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Moulton VR, Lo MS, Tsokos GC. Methods and protocols to study T cell signaling abnormalities in human systemic lupus erythematosus. Methods Mol Biol 2012; 900:25-60. [PMID: 22933064 DOI: 10.1007/978-1-60761-720-4_3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Abnormal expression of key signaling molecules and defective functions of T lymphocytes play a significant role in the pathogenesis of systemic lupus erythematosus (SLE). T cell receptor (TCR/CD3)-mediated stimulation of SLE T cells show increased protein tyrosine phosphorylation of cellular proteins with faster kinetics, heightened calcium flux response, and decreased IL-2 production. The molecular mechanisms of T cell signaling abnormalities in SLE T cells are complex. Current research has been directed towards investigating various factors that contribute to abnormal tyrosine phosphorylation, intracellular calcium response, and cytokine production. Central to this dysfunction is the aberrant expression and function of the TCR/CD3ζ chain. Latest developments suggest multiple explanations are involved, including altered receptor structure, supramolecular assembly, modulation of membrane clustering, aberrant cellular distribution, and pre-compartmentalization with lipid-rafts. The methods and protocols described here pertaining to T cell signaling abnormalities in SLE T cells are optimized in many ways and are derived by the combined task and continuous efforts of many researchers in the lab over a long period of time. These simplified protocols can be readily applied to study T cell signaling abnormalities in SLE to identify the genetic, molecular, and biochemical factors contributing to aberrant immune cell function and unravel the pathophysiology of SLE.
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Affiliation(s)
- Vaishali R Moulton
- Division of Rheumatology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
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Localisation to lipid rafts correlates with increased function of the Gal/GalNAc lectin in the human protozoan parasite, Entamoeba histolytica. Int J Parasitol 2011; 41:1409-19. [PMID: 22085647 DOI: 10.1016/j.ijpara.2011.10.003] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2011] [Revised: 09/23/2011] [Accepted: 10/06/2011] [Indexed: 11/24/2022]
Abstract
Entamoeba histolytica is the causative agent of dysentery and liver abscess and is prevalent in developing countries. Adhesion to the host is critical to infection and is mediated by amoebic surface receptors. One such receptor, the Gal/GalNAc lectin, binds to galactose or N-acetylgalactosamine residues on host components and consists of heavy (Hgl), light (Lgl) and intermediate (Igl) subunits. The mechanism by which the lectin assembles into a functional complex is not known. The parasite also relies on cholesterol-rich domains (lipid rafts) for adhesion. Therefore, it is conceivable that rafts regulate the assembly or function of the lectin. To test this, amoebae were loaded with cholesterol and lipid rafts were purified and characterised. Western blotting showed that cholesterol loading resulted in co-compartmentalisation of all three subunits in rafts. This co-compartmentalisation was accompanied by an increase in the ability of the amoebae to bind to host cells in a galactose-specific manner, suggesting that there is a correlation between location and function of the Gal/GalNAc lectin. Cholesterol loading did not increase the surface levels of the lectin subunits. Therefore, the cholesterol-induced increase in adhesion was not the result of externalisation of an internal pool of subunits. A mutant cell line that modestly responded to cholesterol with a slight increase in adhesion exhibited only a slight enrichment of Hgl and Lgl in rafts. This supports the connection between location and function of the Gal/GalNAc lectin. Actin can also influence the interaction of proteins with rafts. Therefore, the sub-membrane distribution of the lectin subunits was also assessed after treatment with an actin depolymerising agent, cytochalasin D. Cytochalasin D-treatment had no effect on the submembrane distribution of the subunits, suggesting that actin does not prevent the association of lectin subunits with rafts in this system. Together, these data provide insight into the molecular mechanisms regulating the location and function of this adhesin.
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Jin S, Zhou F, Katirai F, Li PL. Lipid raft redox signaling: molecular mechanisms in health and disease. Antioxid Redox Signal 2011; 15:1043-83. [PMID: 21294649 PMCID: PMC3135227 DOI: 10.1089/ars.2010.3619] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Lipid rafts, the sphingolipid and cholesterol-enriched membrane microdomains, are able to form different membrane macrodomains or platforms upon stimulations, including redox signaling platforms, which serve as a critical signaling mechanism to mediate or regulate cellular activities or functions. In particular, this raft platform formation provides an important driving force for the assembling of NADPH oxidase subunits and the recruitment of other related receptors, effectors, and regulatory components, resulting, in turn, in the activation of NADPH oxidase and downstream redox regulation of cell functions. This comprehensive review attempts to summarize all basic and advanced information about the formation, regulation, and functions of lipid raft redox signaling platforms as well as their physiological and pathophysiological relevance. Several molecular mechanisms involving the formation of lipid raft redox signaling platforms and the related therapeutic strategies targeting them are discussed. It is hoped that all information and thoughts included in this review could provide more comprehensive insights into the understanding of lipid raft redox signaling, in particular, of their molecular mechanisms, spatial-temporal regulations, and physiological, pathophysiological relevances to human health and diseases.
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Affiliation(s)
- Si Jin
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China.
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11
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Beemiller P, Krummel MF. Mediation of T-cell activation by actin meshworks. Cold Spring Harb Perspect Biol 2010; 2:a002444. [PMID: 20702599 DOI: 10.1101/cshperspect.a002444] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Although the actin cytoskeleton and T-cell receptor (TCR) signaling complexes are seemingly distinct molecular structures, they are tightly integrated in T cells. The signaling pathways initiated by TCRs binding to peptide MHC complexes are extensively influenced by the actin cytoskeletal activities of the motile phase before TCR signaling, the signalosome scaffolding function of the cytoskeleton, and the translocation of signaling clusters that precedes the termination of signaling at these complexes. As these three successive phases constitute essentially all the steps consequent to immune synapse formation, it has become clear that the substantial physical forces and signaling interactions generated by the actin cytoskeleton dominate the signaling life cycle of TCR signalosomes. We discuss the contributions of the actin cytoskeleton to TCR signaling phases and model some remaining questions about how specific cytoskeletal factors regulate TCR signaling outcomes.
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Affiliation(s)
- Peter Beemiller
- Department of Pathology, University of California, San Francisco, San Francisco, California 94143-0511, USA
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12
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Finetti F, Savino MT, Baldari CT. Positive and negative regulation of antigen receptor signaling by the Shc family of protein adapters. Immunol Rev 2010; 232:115-34. [PMID: 19909360 DOI: 10.1111/j.1600-065x.2009.00826.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The Shc adapter family includes four members that are expressed as multiple isoforms and participate in signaling by a variety of cell-surface receptors. The biological relevance of Shc proteins as well as their variegated function, which relies on their highly conserved modular structure, is underscored by the distinct and dramatic phenotypic alterations resulting from deletion of individual Shc isoforms both in the mouse and in two model organisms, Drosophila melanogaster and Caenorhabditis elegans. The p52 isoform of ShcA couples antigen and cytokine receptors to Ras activation in both lymphoid and myeloid cells. However, the recognition of the spectrum of activities of p52ShcA in the immune system has been steadily expanding in recent years to other fundamental processes both at the cell and organism levels. Two other Shc family members, p66ShcA and p52ShcC/Rai, have been identified recently in T and B lymphocytes, where they antagonize survival and attenuate antigen receptor signaling. These developments reveal an unexpected and complex interplay of multiple Shc proteins in lymphocytes.
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Affiliation(s)
- Francesca Finetti
- Department of Evolutionary Biology, University of Siena, Siena, Italy
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Silveira e Souza AMM, Trindade ES, Jamur MC, Oliver C. Gangliosides are important for the preservation of the structure and organization of RBL-2H3 mast cells. J Histochem Cytochem 2009; 58:83-93. [PMID: 19786609 DOI: 10.1369/jhc.2009.954776] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Gangliosides are known to be important in many biological processes. However, details concerning the exact function of these glycosphingolipids in cell physiology are poorly understood. In this study, the role of gangliosides present on the surface of rodent mast cells in maintaining cell structure was examined using RBL-2H3 mast cells and two mutant cell lines (E5 and D1) deficient in the gangliosides, GM(1) and the alpha-galactosyl derivatives of the ganglioside GD(1b). The two deficient cell lines were morphologically different from each other as well as from the parental RBL-2H3 cells. Actin filaments in RBL-2H3 and E5 cells were under the plasma membrane following the spindle shape of the cells, whereas in D1 cells, they were concentrated in large membrane ruffles. Microtubules in RBL-2H3 and E5 cells radiated from the centrosome and were organized into long, straight bundles. The bundles in D1 cells were thicker and organized circumferentially under the plasma membrane. The endoplasmic reticulum, the Golgi complex, and the secretory granule matrix were also altered in the mutant cell lines. These results suggest that the mast cell-specific alpha-galactosyl derivatives of ganglioside GD(1b) and GM(1) are important in maintaining normal cell morphology.
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Affiliation(s)
- Adriana Maria Mariano Silveira e Souza
- Department of Cell and Molecular Biology and Pathogenic Bioagents, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Avenida Bandeirantes 3900, Ribeirão Preto, SP, Brazil
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Meknache N, Jönsson F, Laurent J, Guinnepain MT, Daëron M. Human basophils express the glycosylphosphatidylinositol-anchored low-affinity IgG receptor FcgammaRIIIB (CD16B). THE JOURNAL OF IMMUNOLOGY 2009; 182:2542-50. [PMID: 19201911 DOI: 10.4049/jimmunol.0801665] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Basophils express not only high-affinity IgE receptors, but also low-affinity IgG receptors. Which, among these receptors, are expressed by human basophils is poorly known. Low-affinity IgG receptors comprise CD32 (FcgammaRIIA, FcgammaRIIB, and FcgammaRIIC) and CD16 (FcgammaRIIIA and FcgammaRIIIB). FcgammaRIIA, FcgammaRIIC, and FcgammaRIIIA are activating receptors, FcgammaRIIB are inhibitory receptors, FcgammaRIIIB are GPI-anchored receptors whose function is poorly understood. Basophils were reported to express FcgammaRII, but not FcgammaRIII. We aimed at further identifying basophil IgG receptors. Basophils from normal donors and from patients suffering from an allergic skin disease (atopic dermatitis), allergic respiratory diseases (allergic rhinitis and asthma), or a nonallergic skin disease (chronic urticaria) were examined. We found that normal basophils contain FcgammaRIII transcripts and express FcgammaRIIIB, but not FcgammaRIIIA, which were detected on 24-81% basophils from normal donors and on 12-100% basophils from patients. Noticeably, the proportion of FcgammaRIIIB(+) basophils was significantly lower in atopic dermatitis patients than in other subjects. This decreased FcgammaRIII expression was not correlated with an activated phenotype of basophils in atopic dermatitis patients, although FcgammaRIIIB expression was down-regulated upon basophil activation by anti-IgE. Our results challenge the two dogmas 1) that basophils do not express FcgammaRIII and 2) that FcgammaRIIIB is exclusively expressed by neutrophils. They suggest that a proportion of basophils may be lost during enrichment procedures in which FcgammaRIII(+) cells are discarded by negative sorting using anti-CD16 Abs. They unravel an unexpected complexity of IgG receptors susceptible to modulate basophil activation. They identify a novel systemic alteration in atopic dermatitis.
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Affiliation(s)
- Nihad Meknache
- Institut Pasteur, Département d'Immunologie, Unité d'Allergologie Moléculaire et Cellulaire, Paris, France
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Cronin SJF, Penninger JM. From T-cell activation signals to signaling control of anti-cancer immunity. Immunol Rev 2008; 220:151-68. [PMID: 17979845 DOI: 10.1111/j.1600-065x.2007.00570.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
The activation of resting T cells is crucial to most immune processes. Recognition of foreign antigen by T-cell receptors has to be correctly translated into signal transduction events necessary for the induction of an effective immune response. In this review, we discuss the essential signals, molecules, and processes necessary to achieve full T-cell activation. In addition to describing these key biological events, we also discuss how T-cell receptor signaling may be harnessed to yield new therapeutic targets for a next generation of anti-cancer drugs.
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Affiliation(s)
- Shane J F Cronin
- IMBA, Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Vienna, Austria
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16
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Kusel JR, Al-Adhami BH, Doenhoff MJ. The schistosome in the mammalian host: understanding the mechanisms of adaptation. Parasitology 2007; 134:1477-526. [PMID: 17572930 DOI: 10.1017/s0031182007002971] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
SUMMARYIn this review, we envisage the host environment, not as a hostile one, since the schistosome thrives there, but as one in which the relationship between the two organisms consists of constant communication, through signalling mechanisms involving sense organs, surface glycocalyx, surface membrane and internal organs of the parasite, with host fluids and cells. The surface and secretions of the schistosome egg have very different properties from those of other parasite stages, but adapted for the dispersal of the eggs and for the preservation of host liver function. We draw from studies of mammalian cells and other organisms to indicate how further work might be carried out on the signalling function of the surface glycocalyx, the raft structure of the surface and existence of pores in the surface membrane, the repair of the surface membrane, the role of the membrane structure in ion channel function (including recent work on the actin cytoskeleton and calcium channels) and the possible role of P-glycoproteins in the adaptation of the parasite to its environment. We are speculative in some areas, such as the suggestions that variability in surface properties of schistosomes may relate to the existence of membrane rafts and that parasite communities may exhibit quorum sensing. This speculative approach is adopted with the hope that future work on the whole organisms and their interactions will be encouraged.
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Affiliation(s)
- J R Kusel
- Glasgow Biomedical Research Centre, University of Glasgow, Glasgow G12 8TA, UK.
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17
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Juncadella IJ, Garg R, Ananthnarayanan SK, Yengo CM, Anguita J. T-cell signaling pathways inhibited by the tick saliva immunosuppressor, Salp15. ACTA ACUST UNITED AC 2007; 49:433-8. [PMID: 17343683 DOI: 10.1111/j.1574-695x.2007.00223.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The Ixodes scapularis salivary protein Salp15 inhibits the activation of T cells through its interaction with the coreceptor CD4. Salp15 prevents the activation of Lck upon TCR engagement and the formation of lipid rafts. We have now analyzed the signaling pathways that are inhibited by the tick salivary protein in CD4(+) T cells. Salp15 affects tyrosine phosphorylation of several early signal components downstream of Lck, including LAT and Vav1, which results in improper actin polymerization. The effect of Salp15 is due to its interaction with CD4, as no effect was observed in CD4-negative T cells. Finally, we demonstrate that the peptide that mediates the interaction of Salp15 with CD4, P11, is able to recapitulate the immunosuppressive activity of the whole protein. These results clarify the molecular mechanisms of action of Salp15 on T cells and suggest that binding to CD4 is sufficient to elicit its immunosuppressive effect.
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Affiliation(s)
- Ignacio J Juncadella
- Department of Veterinary and Animal Sciences, University of Massachussets Amherst, Amherst, MA 01003, USA
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18
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Ishmael JE, Safic M, Amparan D, Vogel WK, Pham T, Marley K, Filtz TM, Maier CS. Nonmuscle myosins II-B and Va are components of detergent-resistant membrane skeletons derived from mouse forebrain. Brain Res 2007; 1143:46-59. [PMID: 17321505 DOI: 10.1016/j.brainres.2007.01.061] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 01/14/2007] [Accepted: 01/16/2007] [Indexed: 10/23/2022]
Abstract
Myosins are actin-based molecular motors that may have specialized trafficking and contractile functions in cytoskeletal compartments that lack microtubules. The postsynaptic excitatory synapse is one such specialization, yet little is known about the spatial organization of myosin motor proteins in the mature brain. We used a proteomics approach to determine if class II and class V myosin isoforms are associated with Triton X-100-resistant membranes isolated from mouse forebrain. Two nonmuscle myosin isoforms (II-B and Va), were identified as components of lipid raft fractions that also contained typical membrane skeletal proteins such as non-erythrocyte spectrins, actin, alpha-actinin-2 and tubulin subunits. Other raft-associated proteins included lipid raft markers, proteins involved in cell adhesion and membrane dynamics, receptors and channels including glutamate receptor subunits, scaffolding and regulatory proteins. Myosin II-B and Va were also present in standard postsynaptic density (PSD) fractions, however retention of myosin II-B was strongly influenced by ATP status. If homogenates were supplemented with ATP, myosin II-B could be extracted from PSD I whereas myosin Va and other postsynaptic proteins were resistant to extraction. In summary, both myosin isoforms are components of a raft-associated membrane skeleton and are likely detected in standard PSD fractions as a result of their intrinsic ability to form actomyosin. Myosin II-B, however, is more loosely associated with PSD fractions than myosin Va, which appears to be a core PSD protein.
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Affiliation(s)
- Jane E Ishmael
- Department of Pharmaceutical Sciences, College of Pharmacy, Oregon State University, Corvallis, OR 97331, USA.
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19
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Morley SC, Sung J, Sun GP, Martelli MP, Bunnell SC, Bierer BE. Gelsolin overexpression alters actin dynamics and tyrosine phosphorylation of lipid raft-associated proteins in Jurkat T cells. Mol Immunol 2006; 44:2469-80. [PMID: 17178161 PMCID: PMC1945820 DOI: 10.1016/j.molimm.2006.09.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2006] [Accepted: 09/29/2006] [Indexed: 12/18/2022]
Abstract
Upon T cell receptor engagement, both the actin cytoskeleton and substrates of tyrosine phosphorylation are remodeled to create a signaling complex at the interface of the antigen-presenting cell and responding T cell. While T cell signaling has been shown to regulate actin reorganization, the mechanisms by which changes in actin dynamics affect early T cell signaling have not been fully explored. Using gelsolin, an actin-binding protein with capping and severing activities, and latrunculin, an actin-depolymerizing agent, we have further investigated the interplay between actin dynamics and the regulation of T cell signaling. Overexpression of gelsolin altered actin dynamics in Jurkat T cells, and alteration of actin dynamics correlated with dysregulation of tyrosine phosphorylation of raft-associated substrates. This perturbation of tyrosine phosphorylation was correlated with inhibition of activation-dependent signaling pathways regulating Erk-1/2 phosphorylation, NF-AT transcriptional activation and IL-2 production. Modification of actin by the depolymerizing agent latrunculin also altered the tyrosine phosphorylation patterns of proteins associated with lipid rafts, and pre-treatment with latrunculin inhibited anti-CD3 mAb-mediated NF-AT activation. Thus, our data indicate that actin cytoskeletal dynamics modulate the tyrosine phosphorylation of raft-associated proteins and subsequent downstream signal transduction.
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Affiliation(s)
- S Celeste Morley
- Laboratory of Lymphocyte Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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20
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Lee FA, van Lier M, Relou IAM, Foley L, Akkerman JWN, Heijnen HFG, Farndale RW. Lipid rafts facilitate the interaction of PECAM-1 with the glycoprotein VI-FcR gamma-chain complex in human platelets. J Biol Chem 2006; 281:39330-8. [PMID: 17068334 DOI: 10.1074/jbc.m607930200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Glycoprotein (GP) VI, the main signaling receptor for collagen on platelets, is expressed in complex with the FcR gamma-chain. The latter contains an immunoreceptor tyrosine-based activation motif, which becomes phosphorylated, initiating a signaling cascade leading to the rapid activation and aggregation of platelets. Previous studies have shown that signaling by immunoreceptor tyrosine-based activation motif-containing receptors is counteracted by signals from receptors with immunoreceptor tyrosine-based inhibitory motifs. Here we show, by immunoprecipitation, that the GPVI-FcR gamma-chain complex associates with the immunoreceptor tyrosine-based inhibitory motif-containing receptor, PECAM-1. In platelets stimulated with collagen-related peptide (CRP-XL), tyrosine phosphorylation of PECAM-1 precedes that of the FcR gamma-chain, implying direct regulation of the former. The GPVI-FcR gamma-chain complex and PECAM-1 were present in both lipid raft and soluble fractions in human platelets; this distribution was unaltered by activation with CRP-XL. Their association occurred in lipid rafts and was lost after lipid raft depletion using methyl-beta-cyclodextrin. We propose that lipid raft clustering facilitates the interaction of PECAM-1 with the GPVI-FcR gamma-chain complex, leading to the down-regulation of the latter.
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Affiliation(s)
- Fiona A Lee
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
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21
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Liu AP, Fletcher DA. Actin polymerization serves as a membrane domain switch in model lipid bilayers. Biophys J 2006; 91:4064-70. [PMID: 16963509 PMCID: PMC1635687 DOI: 10.1529/biophysj.106.090852] [Citation(s) in RCA: 181] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The ability of cells to mount localized responses to external or internal stimuli is critically dependent on organization of lipids and proteins in the plasma membrane. Involvement of the actin cytoskeleton in membrane organization has been documented, but an active role for actin networks that directly links internal organization of the cytoskeleton with membrane organization has not yet been identified. Here we show that branched actin networks formed on model lipid membranes enriched with the lipid second messenger PIP(2) trigger both temporal and spatial rearrangement of membrane components. Using giant unilamellar vesicles able to separate into two coexisting liquid phases, we demonstrate that polymerization of dendritic actin networks on the membrane induces phase separation of initially homogenous vesicles. This switch-like behavior depends only on the PIP(2)-N-WASP link between the membrane and actin network, and we find that the presence of a preexisting actin network spatially biases the location of phase separation. These results show that dynamic, membrane-bound actin networks alone can control when and where membrane domains form and may actively contribute to membrane organization during cell signaling.
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Affiliation(s)
- Allen P Liu
- Biophysics Program, University of California, Berkeley, CA 94720, USA
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22
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Krzewski K, Chen X, Orange JS, Strominger JL. Formation of a WIP-, WASp-, actin-, and myosin IIA-containing multiprotein complex in activated NK cells and its alteration by KIR inhibitory signaling. ACTA ACUST UNITED AC 2006; 173:121-32. [PMID: 16606694 PMCID: PMC2063796 DOI: 10.1083/jcb.200509076] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The tumor natural killer (NK) cell line YTS was used to examine the cytoskeletal rearrangements required for cytolysis. A multiprotein complex weighing approximately 1.3 mD and consisting of WASp-interacting protein (WIP), Wiskott-Aldrich syndrome protein (WASp), actin, and myosin IIA that formed during NK cell activation was identified. After induction of an inhibitory signal, the recruitment of actin and myosin IIA to a constitutive WIP-WASp complex was greatly decreased. Both actin and myosin IIA were recruited to WIP in the absence of WASp. This recruitment correlated with increased WIP phosphorylation, which was mediated by PKCtheta. Furthermore, the disruption of WIP expression by WIP RNA interference prevented the formation of this protein complex and led to almost complete inhibition of cytotoxic activity. Thus, the multiprotein complex is important for NK cell function, killer cell immunoglobulin-like receptor inhibitory signaling affects proteins involved in cytoskeletal rearrangements, and WIP plays a central role in the formation of the complex and in the regulation of NK cell activity.
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Affiliation(s)
- Konrad Krzewski
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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23
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Langhorst MF, Reuter A, Luxenhofer G, Boneberg EM, Legler DF, Plattner H, Stuermer CAO. Preformed reggie/flotillin caps: stable priming platforms for macrodomain assembly in T cells. FASEB J 2006; 20:711-3. [PMID: 16452278 DOI: 10.1096/fj.05-4760fje] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
T cell activation after contact with an antigen-presenting cell depends on the regulated assembly of the T cell receptor signaling complex, which involves the polarized assembly of a stable, raft-like macrodomain surrounding engaged T cell receptors. Here we show that the preformed reggie/flotillin caps present in resting T cells act as priming platforms for macrodomain assembly. Preformed reggie-1/flotillin-2 caps are exceptionally stable, as shown by fluorescence recovery after photobleaching (FRAP). Upon T cell stimulation, signaling molecules are recruited to the stable reggie/flotillin caps. Importantly, a trans-negative reggie-1/flotillin-2 deletion mutant, which interferes with assembly of the preformed reggie/flotillin cap, impairs raft polarization and macrodomain formation after T cell activation. Accordingly, expression of the trans-negative reggie-1 mutant leads to the incorrect positioning of the guanine nucleotide exchange factor Vav, resulting in defects in cytoskeletal reorganization. Thus, the preformed reggie/flotillin caps are stable priming platforms for the assembly of multiprotein complexes controlling actin reorganization during T cell activation.
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Affiliation(s)
- Matthias F Langhorst
- Developmental Neurobiology Group, Department of Biology, University of Konstanz, Konstanz, Germany.
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24
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MacLellan DL, Steen H, Adam RM, Garlick M, Zurakowski D, Gygi SP, Freeman MR, Solomon KR. A quantitative proteomic analysis of growth factor-induced compositional changes in lipid rafts of human smooth muscle cells. Proteomics 2005; 5:4733-42. [PMID: 16267816 DOI: 10.1002/pmic.200500044] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Signals that promote proliferation and migration of smooth muscle cells (SMC) have been implicated in pathologic growth of hollow organs. Members of the platelet-derived growth factor (PDGF) family, potent mitogens and motility factors for SMC, have been shown to signal through cholesterol-enriched lipid rafts. We recently demonstrated that PDGF-stimulated DNA synthesis in urinary tract SMC was dependent on the integrity of lipid rafts. Despite its known ability to rapidly alter discrete proteins within rafts, the effect of PDGF on overall raft protein composition is unknown. In this study, we employed isotope coded affinity tag (ICAT) analysis to evaluate PDGF-induced protein changes in lipid rafts of primary culture human SMC. Following acute (i.e., 15 min) exposure of SMC to PDGF, 23 proteins increased in rafts >20%. In contrast, raft localization of only three proteins increased after 12 h of PDGF treatment. Among the proteins that increased at 15 min were the glycophosphatidylinositol-anchored proteins Thy-1, 5'-nucleotidase, and CD55, the cytoskeletal proteins actin, actinin, tropomyosin-3 and -4, and the endocytosis-related proteins clathrin and beta-adaptin. In addition, eight Rho family members were localized to rafts by ICAT analysis. Collectively, these observations suggest a role for lipid rafts in regulation of PDGF-stimulated changes in the cytoskeleton.
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Affiliation(s)
- Dawn L MacLellan
- Department of Urology, The Urological Diseases Research Center, Boston, MA, USA
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25
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Viard M, Parolini I, Rawat SS, Fecchi K, Sargiacomo M, Puri A, Blumenthal R. The role of glycosphingolipids in HIV signaling, entry and pathogenesis. Glycoconj J 2005; 20:213-22. [PMID: 15090735 DOI: 10.1023/b:glyc.0000024253.48791.d9] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Although HIV uses CD4 and coreceptors (CCR5 and CXCR4) for productive infection of T cells, glycosphingolipids (GSL) may play ancillary roles in lymphoid and non-lymphoid cells. Interactions of the HIV Envelope Glycoprotein (Env) with GSL may help HIV in various steps of its pathogenesis. Physical-chemical aspects of the interactions between HIV Env and GSL leading to CD4-dependent entry into lymphocytes, the role of GSL in HIV transcytosis, and CD4-independent entry into non-lymphoid cells are reviewed. An overview of signaling properties of HIV receptors is provided with some speculation on how GSL may play a role in these events by virtue of being in membrane rafts. Finally, we summarize how interactions between HIV and coreceptors leading to signaling and/or fusion can be analyzed by the use of various tyrosine kinase and cytoskeletal inhibitors.
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Affiliation(s)
- Mathias Viard
- Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute-Frederick, National Institutes of Health, Frederick, MD, USA
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26
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Boyle EC, Finlay BB. Leaky guts and lipid rafts. Trends Microbiol 2005; 13:560-3. [PMID: 16253506 DOI: 10.1016/j.tim.2005.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 09/09/2005] [Accepted: 10/06/2005] [Indexed: 10/25/2022]
Abstract
The intestinal epithelium functions as a physical barrier separating luminal microorganisms from the underlying immune system. There is compelling evidence that several intestinal diseases are associated with the translocation of commensal bacteria across the epithelial barrier. Recent work has identified a novel mechanism by which normally non-invasive enteric bacteria breach the intestinal epithelium during periods of inflammation.
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Affiliation(s)
- Erin C Boyle
- Michael Smith Laboratories, 2185 East Mall, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada
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27
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Krishnan S, Kiang JG, Fisher CU, Nambiar MP, Nguyen HT, Kyttaris VC, Chowdhury B, Rus V, Tsokos GC. Increased caspase-3 expression and activity contribute to reduced CD3zeta expression in systemic lupus erythematosus T cells. THE JOURNAL OF IMMUNOLOGY 2005; 175:3417-23. [PMID: 16116236 DOI: 10.4049/jimmunol.175.5.3417] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
T cells isolated from patients with systemic lupus erythematosus (SLE) express low levels of CD3zeta-chain, a critical molecule involved in TCR-mediated signaling, but the involved mechanisms are not fully understood. In this study we examined caspase-3 as a candidate for cleaving CD3zeta in SLE T cells. We demonstrate that SLE T cells display increased expression and activity of caspase-3. Treatment of SLE T cells with the caspase-3 inhibitor Z-Asp-Glu-Val-Asp-FMK reduced proteolysis of CD3zeta and enhanced its expression. In addition, Z-Asp-Glu-Val-Asp-FMK treatment increased the association of CD3zeta with lipid rafts and simultaneously reversed the abnormal lipid raft preclustering, heightened TCR-induced calcium responses, and reduced the expression of FcRgamma-chain exclusively in SLE T cells. We conclude that caspase-3 inhibitors can normalize SLE T cell function by limiting the excessive digestion of CD3zeta-chain and suggest that such molecules can be considered in the treatment of this disease.
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Affiliation(s)
- Sandeep Krishnan
- Department of Cellular Injury, Walter Reed Army Institute of Research, Silver Spring, MD 20910-7500, USA
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28
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Meiri KF. Lipid rafts and regulation of the cytoskeleton during T cell activation. Philos Trans R Soc Lond B Biol Sci 2005; 360:1663-72. [PMID: 16147530 PMCID: PMC1569545 DOI: 10.1098/rstb.2005.1704] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability of polarized cells to initiate and sustain directional responses to extracellular signals is critically dependent on direct communication between spatially organized signalling modules in the membrane and the underlying cytoskeleton. Pioneering work in T cells has shown that the assembly of signalling modules critically depends on the functional compartmentalization of membrane lipids into ordered microdomains or lipid rafts. The significance of rafts in T cell activation lies not only in their ability to recruit the signalling partners that eventually assemble into a mature immunological synapse but also in their ability to regulate actin dynamics and recruit cytoskeletal associated proteins, thereby achieving the structural polarization underlying stability of the synapse-a critical prerequisite for activation to be sustained. Lipid rafts vary quite considerably in size and visualizing the smallest of them in vivo has been challenging. Nonetheless it is now been shown quite convincingly that a surprisingly large proportion-in the order of 50%-of external membrane lipids (chiefly cholesterol and glycosphingolipids) can be dynamically localized in these liquid ordered rafts. Complementary inner leaflet rafts are less well characterized, but contain phosphoinositides as an important functional component that is crucial for regulating the behaviour of the actin cytoskeleton. This paper provides an overview of the interdependency between signalling and cytoskeletal polarization, and in particular considers how regulation of the cytoskeleton plays a crucial role in the consolidation of rafts and their stabilization into the immunological synapse.
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Affiliation(s)
- Karina F Meiri
- Department of Anatomy and Cellular Biology , Tufts University School of Medicine, Boston, MA 02111, USA.
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29
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Groves JT. Molekulare Organisation und Signaltransduktion an Kontaktstellen zwischen Membranen. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200461014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Groves JT. Molecular Organization and Signal Transduction at Intermembrane Junctions. Angew Chem Int Ed Engl 2005; 44:3524-38. [PMID: 15844101 DOI: 10.1002/anie.200461014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Surfaces create an environment in which multiple forces conspire together to yield a wealth of complex chemical processes. This is especially true of cell membranes, whose fluidity and flexibility enables responsive feedback with surface chemical interactions in ways not generally seen with inorganic materials. Spatial pattern formation of cell-surface proteins at intermembrane junctions provides many beautiful examples of these phenomena, and is also emerging as a functional aspect of intercellular signaling. Correspondingly, the study of interactions of cell-membrane surfaces is attracting significant attention from cell biologists and physical chemists alike. This convergence is fueled be recent, exquisite observations of protein pattern formation events within living immunological synapses along with parallel advances in membrane reconstitution, manipulation, and imaging technologies.
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Affiliation(s)
- Jay T Groves
- Department of Chemistry, University of California Berkeley, USA.
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31
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Tian W, Feng B, Liou HC. Silencing OCILRP2 leads to intrinsic defects in T cells in response to antigenic stimulation. Cell Immunol 2005; 235:72-84. [PMID: 16143319 DOI: 10.1016/j.cellimm.2005.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2005] [Revised: 07/01/2005] [Accepted: 07/14/2005] [Indexed: 10/25/2022]
Abstract
We have previously demonstrated that OCILRP2 interaction with its ligand NKRP1f provides a co-stimulatory signal for optimal T cell proliferation and IL-2 production. Here, using RNA interference technology, we will demonstrate that silencing OCILRP2 in vivo leads to intrinsic impairment in T cell response to CD3- and CD28-cross-linking as well as antigenic stimulation. OCILRP2-silenced T cells have reduced cell proliferation and IL-2 production, which can be bypassed by PMA and ionomycin treatment. OCILRP2-silenced T cells also failed to undergo TCR capping and had impaired cytoskeleton reorganization. Moreover, in OCILRP2-silenced T cells, tyrosine phosphorylation of Lck was diminished, while tyrosine phosphorylation of linkers for activation of T cells was unchanged. Interestingly, NF-kappaB activation was also impaired as the result of OCILRP2 silencing. Together, our data strongly support a novel role for OCILRP2 C-type lectin in TCR-mediated signal transduction. The observation that OCILRP2 is involved in TCR capping and cytoskeletal organization suggests that OCILRP2-NKRP1f may facilitate lipid rafts and immunological synapse formation during T cell interaction with antigen presenting cells.
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Affiliation(s)
- Wenzhi Tian
- Division of Immunology, Department of Medicine, Weill Medical College of Cornell University, New York, NY 10021, USA
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32
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Söderström TS, Nyberg SD, Eriksson JE. CD95 capping is ROCK-dependent and dispensable for apoptosis. J Cell Sci 2005; 118:2211-23. [PMID: 15855233 DOI: 10.1242/jcs.02343] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Upon engagement, the CD95 receptor is rapidly clustered into cellular 'caps'. This receptor capping is one of the first events to take place following activation and it has been proposed to be important for the initiation of apoptotic signaling. As the biological roles of CD95 capping are still elusive, we explored in detail the role of capping in induction of apoptosis in lymphocytes. CD95 capping was shown to be uncoupled from apoptosis, as apoptosis could occur in the absence of CD95 capping and, vice versa, capping could occur without inducing apoptosis. CD95 capping occurred concomitantly with reorganization of the actin cytoskeleton and aggregation of lipid rafts. While inhibition of actin polymerization and caspase-8 activity had cell type-specific effects on capping in type I and type II cells, the rapid CD95-mediated cellular polarization, as visualized by the orchestrated reorganization of CD95, F-actin and lipid rafts, was shown to be dependent on signaling by Rho kinase (ROCK) in both cell types, however, by distinct activation mechanisms in the respective cell type. CD95 activated RhoA exclusively in the type II cell, whereas ROCK activation was caspase-dependent in the type I cell. Taken together, our results imply that CD95 capping and the subsequent cellular polarization is a ROCK signaling-regulated process that does not correlate with the induction of apoptosis, but is more likely to be involved in the emerging non-apoptotic functions of CD95.
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33
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Paccani SR, Boncristiano M, Patrussi L, Ulivieri C, Wack A, Valensin S, Hirst TR, Amedei A, Del Prete G, Telford JL, D'Elios MM, Baldari CT. Defective Vav expression and impaired F-actin reorganization in a subset of patients with common variable immunodeficiency characterized by T-cell defects. Blood 2005; 106:626-34. [PMID: 15817684 DOI: 10.1182/blood-2004-05-2051] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Common variable immunodeficiency (CVID) is a primary immune disorder characterized by impaired antibody production, which is in many instances secondary to defective T-cell function (T-CVID). We have previously identified a subset of patients with T-CVID characterized by defective T-cell receptor (TCR)-dependent protein tyrosine phosphorylation. In these patients, ZAP-70 fails to be recruited to the TCR as the result of impaired CD3zeta phosphorylation, which is, however, not dependent on defective Lck expression or activity. Here we show that neither Fyn nor CD45 is affected in these patients. On the other hand, T-CVID T cells show dramatic defects in the Vav/Rac pathway controlling F-actin dynamics. A significant deficiency in Vav protein was indeed observed; in 3 of 4 patients with T-CVID, it was associated with reduced VAV1 mRNA levels. The impairment in Vav expression correlated with defective F-actin reorganization in response to TCR/CD28 co-engagement. Furthermore, TCR/CD28-dependent up-regulation of lipid rafts at the cell surface, which requires F-actin dynamics, was impaired in these patients. The actin cytoskeleton defect could be reversed by reconstitution of Vav1 expression in the patients' T cells. Results demonstrate an essential role of Vav in human T cells and strongly suggest Vav insufficiency in T-CVID.
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Affiliation(s)
- Silvia Rossi Paccani
- Department of Evolutionary Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy
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34
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McDonald TP, Pitt AR, Brown G, Rixon HWM, Sugrue RJ. Evidence that the respiratory syncytial virus polymerase complex associates with lipid rafts in virus-infected cells: a proteomic analysis. Virology 2005; 330:147-57. [PMID: 15527841 DOI: 10.1016/j.virol.2004.09.034] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2004] [Revised: 08/31/2004] [Accepted: 09/28/2004] [Indexed: 10/26/2022]
Abstract
The interaction between the respiratory syncytial virus (RSV) polymerase complex and lipid rafts was examined in HEp2 cells. Lipid-raft membranes were prepared from virus-infected cells and their protein content was analysed by Western blotting and mass spectrometry. This analysis revealed the presence of the N, P, L, M2-1 and M proteins. However, these proteins appeared to differ from one another in their association with these structures, with the M2-1 protein showing a greater partitioning into raft membranes compared to that of the N, P or M proteins. Determination of the polymerase activity profile of the gradient fractions revealed that 95% of the detectable viral enzyme activity was associated with lipid-raft membranes. Furthermore, analysis of virus-infected cells by confocal microscopy suggested an association between these proteins and the raft-lipid, GM1. Together, these results provide evidence that the RSV polymerase complex is able to associate with lipid rafts in virus-infected cells.
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35
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Hao S, August A. Actin depolymerization transduces the strength of B-cell receptor stimulation. Mol Biol Cell 2005; 16:2275-84. [PMID: 15728723 PMCID: PMC1087234 DOI: 10.1091/mbc.e04-10-0881] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Polymerization of the actin cytoskeleton has been found to be essential for B-cell activation. We show here, however, that stimulation of BCR induces a rapid global actin depolymerization in a BCR signal strength-dependent manner, followed by polarized actin repolymerization. Depolymerization of actin enhances and blocking actin depolymerization inhibits BCR signaling, leading to altered BCR and lipid raft clustering, ERK activation, and transcription factor activation. Furthermore actin depolymerization by itself induces altered lipid raft clustering and ERK activation, suggesting that F-actin may play a role in separating lipid rafts and in setting the threshold for cellular activation.
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Affiliation(s)
- Shengli Hao
- Immunology Research Laboratories, Department of Veterinary Science, The Pennsylvania State University, University Park, PA 16802, USA
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36
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Geyeregger R, Zeyda M, Zlabinger GJ, Waldhäusl W, Stulnig TM. Polyunsaturated fatty acids interfere with formation of the immunological synapse. J Leukoc Biol 2005; 77:680-8. [PMID: 15703198 DOI: 10.1189/jlb.1104687] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Polyunsaturated fatty acids (PUFAs) exert inhibitory effects on T cell-mediated immune responses. Activation of T cells in vivo depends on formation of an immunological synapse (IS) at the T cell/antigen-presenting cell (APC) interface. Here, we analyzed effects of PUFA treatment on the formation of the IS and APC-induced human T cell activation. In T cells treated with the PUFA eicosapentaenoic (EPA; 20:5,n-3) and arachidonic acid (20:4,n-6), stimulated by superantigen-presenting cells or APCs, relocalization to the IS of distinct molecules [F-actin, talin, leukocyte functional antigen-1alpha, clusters of differentiation (CD)3epsilon] was inhibited markedly compared with cells treated with saturated fatty acid, whereas relocalization of protein kinase Ctheta to the IS remained unaffected. CD3-induced, sustained phosphorylation of nucleotide exchange factor Vav, which controls cytoskeletal rearrangements underlying IS formation, was significantly reduced in EPA-treated Jurkat and peripheral blood T cells. In addition, T cell raft disruption by methyl-beta-cyclodextrin treatment and experiments with a chimeric linker for activation of T cell proteins, which is resistant to PUFA effects on lipid rafts, revealed modifications of lipid rafts as a crucial factor for PUFA-mediated inhibition of APC-stimulated cytoskeletal rearrangements. Furthermore, the efficiency of T cell/APC conjugate formation was significantly reduced with EPA-treated T cells, as was stimulation of CD69 expression, which is not altered following antibody-mediated T cell activation. In conclusion, PUFA treatment of T cells qualitatively and quantitatively alters IS formation, thereby extending T cell signaling defects to pathways that are not intrinsically altered in PUFA-treated T cells when stimulated by antibodies.
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Affiliation(s)
- René Geyeregger
- Department of Internal Medicine, Medical University of Vienna, Währinger Gürtel 18-20, A-1090 Vienna, Austria
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37
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Köhler K, Lellouch AC, Vollmer S, Stoevesandt O, Hoff A, Peters L, Rogl H, Malissen B, Brock R. Chemical Inhibitors when Timing Is Critical: A Pharmacological Concept for the Maturation of T Cell Contacts. Chembiochem 2005; 6:152-61. [PMID: 15637666 DOI: 10.1002/cbic.200400241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Cellular signal transduction proceeds through a complex network of molecular interactions and enzymatic activities. The timing of these molecular events is critical for the propagation of a signal and the generation of a specific cellular response. To define the timing of signalling events, we introduce the combination of high-resolution confocal microscopy with the application of small-molecule inhibitors at various stages of signal transduction in T cells. Inhibitors of Src-family tyrosine kinases and actin dynamics were employed to dissect the role of the lymphocyte-specific tyrosine kinase Lck in the formation and maintenance of T cell receptor/CD3-dependent contacts. Anti-CD3epsilon-coated coverslips served as a highly defined stimulus. The kinetics of the recruitment of the yellow fluorescent protein-tagged signalling protein ZAP-70 were detected by high-resolution confocal microscopy. The analysis revealed that at 5 min after receptor engagement, Lck activity was required for maintenance of contacts. In contrast, after 20 min of receptor engagement, the contacts were Lck-independent. The relevance of the timing of inhibitor application provides a pharmacological concept for the maturation of T cell-substrate contacts.
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Affiliation(s)
- Karsten Köhler
- Group of Cellular Signalling, Institute for Cell Biology, University of Tübingen, Auf der Morgenstelle 15, 72076 Tübingen, Germany
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38
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Paccani SR, Patrussi L, Ulivieri C, Masferrer JL, D'Elios MM, Baldari CT. Nonsteroidal anti-inflammatory drugs inhibit a Fyn-dependent pathway coupled to Rac and stress kinase activation in TCR signaling. Blood 2004; 105:2042-8. [PMID: 15514010 DOI: 10.1182/blood-2004-04-1299] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In addition to their anti-inflammatory properties, nonsteroidal anti-inflammatory drugs (NSAIDs) harbor immunosuppressive activities related to their capacity both to inhibit cyclooxygenases (COXs) and to act as peroxisome proliferator-activated receptor (PPAR) ligands. We have previously shown that the stress-activated kinase p38 is a selective target of NSAIDs in T cells. Here we have investigated the effect of NSAIDs on the signaling pathway triggered by the T-cell antigen receptor (TCR) and leading to stress kinase activation. The results show that nonselective and COX-1-selective NSAIDs also block activation of the stress kinase c-Jun N-terminal kinase (JNK) and that prostaglandin-E2 (PGE2) reverses this block and enhances TCR-dependent JNK activation. Analysis of the activation state of the components upstream of p38 and JNK showed that NSAIDs inhibit the serine-threonine kinase p21-activated protein kinase 1 (Pak1) and the small guanosine 5'-triphosphatase (GTPase) Rac, as well as the Rac-specific guanine nucleotide exchanger, Vav. Furthermore, activation of Fyn, which controls Vav phosphorylation, is inhibited by NSAIDs, whereas activation of lymphocyte-specific protein tyrosine kinase (Lck) and of the Lck-dependent tyrosine kinase cascade is unaffected. Accordingly, constitutively active Fyn reverses the NSAID-dependent stress kinase inhibition. The data identify COX-1 as an important early modulator of TCR signaling and highlight a TCR proximal pathway selectively coupling the TCR to stress kinase activation.
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Affiliation(s)
- Silvia Rossi Paccani
- Department of Evolutionary Biology, University of Siena, Siena, Via Aldo Moro 2, 53100 Siena, Italy
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39
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Abstract
Vav proteins are evolutionarily conserved from nematodes to mammals and play a pivotal role in many aspects of cellular signaling, coupling cell surface receptors to various effectors functions. In mammals, there are three family members; Vav1 is specifically expressed in the hematopoietic system, whereas Vav2 and Vav3 are more ubiquitously expressed. Vav proteins contain multiple domains that enable their function in various fashions. The participation of the Vav proteins in several processes that require cytoskeletal reorganization, such as the formation of the immunological synapse (IS), phagocytosis, platelet aggregation, spreading, and transformation will be discussed in this review. We will also cover how the Vav proteins succeed in controlling these processes by their function as guanine nucleotide exchange factors (GEFs) for the Rho/Rac family of GTPases. The contribution of the Vav proteins in a GEF-independent manner to the organization of the cytoskeleton will also be deliberated. The scope of this review is to highlight the numerous roles of the Vav signal transducer proteins in actin organization.
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Affiliation(s)
- Idit Hornstein
- The Hubert H. Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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40
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Friedl P, Storim J. Diversity in immune-cell interactions: states and functions of the immunological synapse. Trends Cell Biol 2004; 14:557-67. [PMID: 15450978 DOI: 10.1016/j.tcb.2004.09.005] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The contact-dependent exchange of signals between epithelial and neuronal cells results from close membrane-membrane appositions, which are stabilized for years by polarized adhesion, cytoskeletal assemblies and extracellular scaffold proteins. By contrast, owing to a lack of scaffold proteins, interactions between immune cells such as T lymphocytes and antigen-presenting cells (APCs) comprise a spectrum of structurally diverse and short-lived interaction modes that last from minutes to hours. Signals exchanged between T cells and APCs are generated in a specific contact region, termed the "immunological synapse", that coordinates cytoskeletal dynamics with the T-cell receptor (TCR), the engagement of accessory receptors and membrane-proximal signaling. Recent data shed light on the different physical and molecular interaction modes that occur between T cells and APCs, including their dynamics and transition stages, and their consequences for signaling, activation and T-cell effector function.
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Affiliation(s)
- Peter Friedl
- Rudolf-Virchow Center, DFG Research Center for Experimental Biomedicine and Department of Dermatology, University of Würzburg, Josef-Schneider-Strasse 2, 97080 Würzburg, Germany.
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41
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Nguyen DH, Espinoza JC, Taub DD. Cellular cholesterol enrichment impairs T cell activation and chemotaxis. Mech Ageing Dev 2004; 125:641-50. [PMID: 15491683 DOI: 10.1016/j.mad.2004.08.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Revised: 08/10/2004] [Accepted: 08/13/2004] [Indexed: 12/28/2022]
Abstract
Human aging is associated with an increase in immune cell cholesterol levels, independent of circulating cholesterol levels. The effects of such an increase in membrane cholesterol on lipid raft-associated immune cell function have not been investigated. We sought to examine the effects of in vitro cholesterol loading on two known lipid raft-associated pathways of T cells, namely T cell activation and chemokine stimulation. Using beta-cyclodextrin (BCD) as a vehicle, we were able to rapidly load cholesterol onto human T cell lines and primary peripheral blood T cells without inducing significant cell toxicity. Loading of cholesterol to four-fold that of normal levels induced significant inhibition of intracellular calcium mobilization by both alphaCD3 and SDF-1alpha. Cholesterol-loaded peripheral T cells were completely unresponsive to alphaCD3/alphaCD28 stimulation, demonstrating no increase in IL-2, GM1 expression or cell size. T cell polarization of lipid rafts to alphaCD3/alphaCD28 beads was also impaired. In addition, cholesterol loading potently inhibited SDF-1alpha-induced chemotaxis. We propose that excess membrane cholesterol could potentially disrupt raft-related cell functions downstream of receptor triggering and that the loss of cholesterol regulation of aging immune cells could contribute to immune cell senescence.
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Affiliation(s)
- Dzung H Nguyen
- Laboratory of Immunology, National Institute on Aging, NIH, Intramural Research Program, 5600 Nathan Shock Drive, Baltimore, MD 21224-6825, USA.
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42
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Badizadegan K, Wheeler HE, Fujinaga Y, Lencer WI. Trafficking of cholera toxin-ganglioside GM1 complex into Golgi and induction of toxicity depend on actin cytoskeleton. Am J Physiol Cell Physiol 2004; 287:C1453-62. [PMID: 15294854 DOI: 10.1152/ajpcell.00189.2004] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Intestinal epithelial lipid rafts contain ganglioside GM1 that is the receptor for cholera toxin (CT). The ganglioside binds CT at the plasma membrane (PM) and carries the toxin through the trans-Golgi network (TGN) to the endoplasmic reticulum (ER). In the ER, a portion of the toxin unfolds and translocates to the cytosol to activate adenylyl cyclase. Activation of the cyclase leads to an increase in intracellular cAMP, which results in apical chloride secretion. Here, we find that an intact actin cytoskeleton is necessary for the efficient transport of CT to the Golgi and for subsequent activation of adenylyl cyclase. CT bound to GM1 on the cell membrane fractionates with a heterogeneous population of lipid rafts, a portion of which is enriched in actin and other cytoskeletal proteins. In this actin-rich fraction of lipid rafts, CT and actin colocalize on the same membrane microdomains, suggesting a possible functional association. Depolymerization or stabilization of actin filaments interferes with transport of CT from the PM to the Golgi and reduces the levels of cAMP generated in the cytosol. Depletion of membrane cholesterol, which also inhibits CT trafficking to the TGN, causes displacement of actin from the lipid rafts while CT remains stably raft associated. On the basis of these observations, we propose that the CT-GM1 complex is associated with the actin cytoskeleton via the lipid rafts and that the actin cytoskeleton plays a role in trafficking of CT from the PM to the Golgi/ER and the subsequent activation of adenylyl cyclase.
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Affiliation(s)
- Kamran Badizadegan
- Department of Pathology, Massachusetts General Hospital, Boston 02114, USA.
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43
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Gordy C, Mishra S, Rodgers W. Visualization of antigen presentation by actin-mediated targeting of glycolipid-enriched membrane domains to the immune synapse of B cell APCs. THE JOURNAL OF IMMUNOLOGY 2004; 172:2030-8. [PMID: 14764667 DOI: 10.4049/jimmunol.172.4.2030] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Glycolipid-enriched membrane (GEM) domains, or lipid rafts, function in signaling in immune cells, but their properties during Ag presentation are less clear. To address this question, GEM domains were studied using fluorescence cell imaging of mouse CH27 B cells presenting Ag to D10 T cells. Our experiments showed that APCs were enriched with GEM domains in the immune synapse, and this occurred in an actin-dependent manner. This enrichment was specific to GEM domains, because a marker for non-GEM regions of the membrane was excluded from the immune synapse. Furthermore, fluorescence photobleaching experiments showed that protein in the immune synapse was dynamic and rapidly exchanged with that in other compartments of CH27 cells. To identify the signals for targeting GEM domains to the immune synapse in APCs, capping of the domains was measured in cells after cross-linking surface molecules. This showed that co-cross-linking CD48 with MHC class II was required for efficient capping and intracellular signaling. Capping of GEM domains by co-cross-linking CD48 and MHC class II occurred with co-capping of filamentous actin, and both domain capping and T cell-CH27 cell conjugation were inhibited by pretreating CH27 cells with latrunculin B. Furthermore, disruption of the actin cytoskeleton of the CH27 cells also inhibited formation of a mature immune synapse in those T cells that did conjugate to APCs. Thus, Ag presentation and efficient T cell stimulation occur by an actin-dependent targeting of GEM domains in the APC to the site of T cell engagement.
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Affiliation(s)
- Claire Gordy
- Molecular Immunogenetics Program, Oklahoma Medical Research Foundation, Oklahoma City, OK 73104, USA
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44
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Djordjevic JT, Schibeci SD, Stewart GJ, Williamson P. HIV type 1 Nef increases the association of T cell receptor (TCR)-signaling molecules with T cell rafts and promotes activation-induced raft fusion. AIDS Res Hum Retroviruses 2004; 20:547-55. [PMID: 15186530 DOI: 10.1089/088922204323087804] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
HIV-1 Nef (Nef) is a myristoylated protein that contributes to HIV disease pathogenesis. Nef has a modulatory effect on T cell receptor (TCR) signaling, resulting in up-regulation of interleukin-2 (IL-2) production in stimulated T cells. Recent studies have shown that efficient TCR signaling requires enhanced association of TCR-signaling molecules with plasma membrane microdomains (lipid rafts) and fusion of rafts into larger structures. We utilized Jurkat T cell lines expressing wild-type Nef (Nef(wt)) and a myristoylation-deficient form of Nef (Nef(G)2(A)), from an inducible promoter, to determine the effects of Nef on the association of TCR-signaling molecules with rafts in nonstimulated T cells. In addition, the effect of Nef on raft size, before and after TCR activation by CD3 cross-linking, was also examined. Following induction, Nef(wt) was associated with both rafts and nonrafts, while Nef(G)2(A) was almost exclusively cytosolic. Induction of Nef(wt), but not Nef(G)2(A), coincided with an increased association of the src family tyrosine kinase, Lck, and TCRzeta with rafts, but not with nonrafts. Further, rafts were found to be significantly larger in CD3-activated T cells in the presence of Nef(wt) when compared to nonexpressing cells. We propose that myristoylated, raft-localized Nef primes resting T cells for activation by increasing the levels of signaling molecules within rafts, and that TCR activation is enhanced by the capacity of Nef to promote raft fusion.
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Affiliation(s)
- Julianne T Djordjevic
- Institute for Immunology and Allergy Research, Westmead Millennium Institute, NSW 2145, Australia
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45
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Rawat SS, Eaton J, Gallo SA, Martin TD, Ablan S, Ratnayake S, Viard M, KewalRamani VN, Wang JM, Blumenthal R, Puri A. Functional expression of CD4, CXCR4, and CCR5 in glycosphingolipid-deficient mouse melanoma GM95 cells and susceptibility to HIV-1 envelope glycoprotein-triggered membrane fusion. Virology 2004; 318:55-65. [PMID: 14972535 DOI: 10.1016/j.virol.2003.08.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2003] [Revised: 08/19/2003] [Accepted: 08/28/2003] [Indexed: 11/27/2022]
Abstract
We had previously reported that glycosphingolipids (GSL) support human immunodeficiency virus type 1 (HIV-1) entry. In this study, we further examined this issue by expressing HIV-1 receptors in GSL-deficient GM95 cells. GM95 cells expressing low levels of CD4 and CXCR4 or CCR5 did not support HIV-1 Env-mediated fusion. However, higher expression of these receptors rendered GM95 cells highly susceptible to fusion with cells expressing appropriate HIV-1 envelope glycoproteins (HIV-1 Envs). The GM95 cells exhibited a different fusion phenotype when compared with GSL(+) NIH3T3 cells bearing similar receptor levels. Fusion of GM95 targets expressing higher levels of CD4 and coreceptors occurred at 25 degrees C and was sensitive to cholesterol depletion or disruption of the cytoskeleton. In contrast, the fusion threshold of NIH3T3CD4X4/R5 targets was at >/=28 degrees C as previously reported and was insensitive to cholesterol depletion or cytoskeletal network disruption. On the basis of these observations, we propose that target membrane GSLs support HIV-1 Env-mediated fusion at low density of receptors by stabilizing receptor pools in natural targets.
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Affiliation(s)
- Satinder S Rawat
- Laboratory of Experimental and Computational Biology, Center for Cancer Research, NCI-Frederick, National Institutes of Health, Frederick, MD 21702-1201, USA
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46
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Meier CL, Svensson M, Kaye PM. Leishmania-induced inhibition of macrophage antigen presentation analyzed at the single-cell level. THE JOURNAL OF IMMUNOLOGY 2004; 171:6706-13. [PMID: 14662874 DOI: 10.4049/jimmunol.171.12.6706] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A number of studies have previously examined the capacity of intracellular Leishmania parasites to modulate the capacity of macrophages to process and present Ags to MHC class II-restricted CD4(+) T cells. However, the bulk culture approaches used for assessing T cell activation make interpretation of some of these studies difficult. To gain a more precise understanding of the interaction between Leishmania-infected macrophages and effector T cells, we have analyzed various parameters of T cell activation in individual macrophage-T cell conjugates. Leishmania-infected macrophages efficiently stimulate Ag-independent as well as Ag-dependent, TCR-mediated capping of cortical F-actin in DO.11 T cells. However, infected macrophages are less efficient at promoting the sustained TCR signaling necessary for reorientation of the T cell microtubule organizing center and for IFN-gamma production. A reduced ability to activate these T cell responses was not due to altered levels of surface-expressed MHC class II-peptide complexes. This study represents the first direct single-cell analysis of the impact of intracellular infection on the interaction of macrophages with T cells and serves to emphasize the subtle influence Leishmania has on APC function.
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Affiliation(s)
- Courtney L Meier
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London, United Kingdom
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47
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Pacini S, Pellegrini M, Migliaccio E, Patrussi L, Ulivieri C, Ventura A, Carraro F, Naldini A, Lanfrancone L, Pelicci P, Baldari CT. p66SHC promotes apoptosis and antagonizes mitogenic signaling in T cells. Mol Cell Biol 2004; 24:1747-57. [PMID: 14749389 PMCID: PMC344195 DOI: 10.1128/mcb.24.4.1747-1757.2004] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Of the three Shc isoforms, p66Shc is responsible for fine-tuning p52/p46Shc signaling to Ras and has been implicated in apoptotic responses to oxidative stress. Here we show that human peripheral blood lymphocytes and mouse thymocytes and splenic T cells acquire the capacity to express p66Shc in response to apoptogenic stimulation. Using a panel of T-cell transfectants and p66Shc(-/-) T cells, we show that p66Shc expression results in increased susceptibility to apoptogenic stimuli, which depends on Ser36 phosphorylation and correlates with an altered balance in apoptosis-regulating gene expression. Furthermore, p66Shc blunts mitogenic responses to T-cell receptor engagement, at least in part by transdominant inhibition of p52Shc signaling to Ras/mitogen-activated protein kinases, in an S36-dependent manner. The data highlight a novel interplay between p66Shc and p52Shc in the control of T-cell fate.
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Affiliation(s)
- Sonia Pacini
- Department of Evolutionary Biology, University of Siena, 53100 Siena, Italy
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48
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Boncristiano M, Paccani SR, Barone S, Ulivieri C, Patrussi L, Ilver D, Amedei A, D'Elios MM, Telford JL, Baldari CT. The Helicobacter pylori vacuolating toxin inhibits T cell activation by two independent mechanisms. ACTA ACUST UNITED AC 2004; 198:1887-97. [PMID: 14676300 PMCID: PMC2194151 DOI: 10.1084/jem.20030621] [Citation(s) in RCA: 209] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Helicobacter pylori toxin, VacA, damages the gastric epithelium by erosion and loosening of tight junctions. Here we report that VacA also interferes with T cell activation by two different mechanisms. Formation of anion-specific channels by VacA prevents calcium influx from the extracellular milieu. The transcription factor NF-AT thus fails to translocate to the nucleus and activate key cytokine genes. A second, channel-independent mechanism involves activation of intracellular signaling through the mitogen-activated protein kinases MKK3/6 and p38 and the Rac-specific nucleotide exchange factor, Vav. As a consequence of aberrant Rac activation, disordered actin polymerization is stimulated. The resulting defects in T cell activation may help H. pylori to prevent an effective immune response leading to chronic colonization of its gastric niche.
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Dolganiuc V, McGinnes L, Luna EJ, Morrison TG. Role of the cytoplasmic domain of the Newcastle disease virus fusion protein in association with lipid rafts. J Virol 2004; 77:12968-79. [PMID: 14645553 PMCID: PMC296069 DOI: 10.1128/jvi.77.24.12968-12979.2003] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To explore the association of the Newcastle disease virus (NDV) fusion (F) protein with cholesterol-rich membrane domains, its localization in detergent-resistant membranes (DRMs) in transfected cells was characterized. After solubilization of cells expressing the F protein with 1% Triton X-100 at 4 degrees C, ca. 40% of total, cell-associated F protein fractionated with classical DRMs with densities of 1.07 to l.14 as defined by flotation into sucrose density gradients. Association of the F protein with this cell fraction was unaffected by the cleavage of F(0) to F(1) and F(2) or by coexpression of the NDV attachment protein, the hemagglutinin-neuraminidase protein (HN). Furthermore, elimination by mutation, of potential palmitate addition sites in and near the F-protein transmembrane domain had no effect on F-protein association with DRMs. Rather, specific deletions of the cytoplasmic domain of the F protein eliminated association with classical DRMs. Comparisons of deletions that affected fusion activity of the protein and deletions that affected DRM association suggested that there is no direct link between the cell-cell fusion activity of the F protein and DRM association. Furthermore, depletion of cholesterol from cells expressing F and HN protein, while eliminating DRM association, had no effect on the ability of these cells to fuse with avian red blood cells. These results suggest that specific localization of the F protein in cholesterol-rich membrane domains is not required for cell-to-cell fusion. Paramyxovirus F-protein cytoplasmic domains have been implicated in virus assembly. The results presented here raise the possibility that the cytoplasmic domain is important in virus assembly at least in part because it directs the protein to cholesterol-rich membrane domains.
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Affiliation(s)
- V Dolganiuc
- Department of Molecular Genetics and Microbiology. Department of Cell Biology. Program in Virology and Immunology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
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50
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Tu X, Huang A, Bae D, Slaughter N, Whitelegge J, Crother T, Bickel PE, Nel A. Proteome Analysis of Lipid Rafts in Jurkat Cells Characterizes a Raft Subset That Is Involved in NF-κB Activation. J Proteome Res 2004; 3:445-54. [PMID: 15253425 DOI: 10.1021/pr0340779] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Lipid rafts are detergent-insoluble membrane domains that play a key role in signal transduction by the T-cell antigen receptor. Proteome analysis revealed the presence of amidosulfobetaine-soluble signal transducing, integral membrane, cytoskeletal, heat shock, and GTP-binding proteins in rafts prepared from Jurkat cells. Several of these proteins were recruited to rafts by CD3/CD28 costimulation. Of particular interest is the inducible association of activated IkappaB kinase complexes with raft vesicles that could be captured with anti-flotillin-1 antibodies. Following amidosulfobetaine solubilization, flotillin-beta and IKKbeta underwent reciprocal co-immunoprecipitation. Treatment of Jurkat cells with methyl-beta-cyclodextrin disrupted the assembly and activation of this raft complex and also interfered in CD3/ CD28-induced activation of a NF-kappaB response element in the IL-2 promoter.
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Affiliation(s)
- Xiaolin Tu
- Division of Clinical Immunology and Allergy, Department of Medicine, The Pasarow Mass Spectrometry Laboratory, University of California, Los Angeles, California 90095, USA
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