共查询到20条相似文献,搜索用时 0 毫秒
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Background
Human T cells play an important role in pathogen clearance, but their aberrant activation is also linked to numerous diseases. T cells are activated by the concurrent induction of the T cell receptor (TCR) and one or more costimulatory receptors. The characterization of signaling pathways induced by TCR and/or costimulatory receptor activation is critical, since these pathways are excellent targets for novel therapies for human disease. Although studies using human T cell lines have provided substantial insight into these signaling pathways, no comprehensive, direct comparison of these cell lines to activated peripheral blood T cells (APBTs) has been performed to validate their usefulness as a model of primary T cells.Methodology/Principal Findings
We used quantitative biochemical techniques to compare the activation of two widely used human T cell lines, Jurkat E6.1 and HuT78 T cells, to APBTs. We found that HuT78 cells were similar to APBTs in proximal TCR-mediated signaling events. In contrast, Jurkat E6.1 cells had significantly increased site-specific phosphorylation of Pyk2, PLCγ1, Vav1, and Erk1/Erk2 and substantially more Ca2+ flux compared to HuT78 cells and APBTs. In part, these effects appear to be due to an overexpression of Itk in Jurkat E6.1 cells compared to HuT78 cells and APBTs. Both cell lines differ from APBTs in the expression and function of costimulatory receptors and in the range of cytokines and chemokines released upon TCR and costimulatory receptor activation.Conclusions/Significance
Both Jurkat E6.1 and HuT78 T cells had distinct similarities and differences compared to APBTs. Both cell lines have advantages and disadvantages, which must be taken into account when choosing them as a model T cell line. 相似文献2.
The role of IL-7 in pre-T cell receptor (TCR) signaling during human T cell development is poorly understood. To study this, we engineered Molt3, a T cell progenitor T-acute lymphoblastic leukemia cell line, using lentiviral IL-7 receptor α (IL-7Rα) to serve as a model system. IL-7 promoted pre-TCR activation in IL-7Rαhi Molt3 as illustrated by CD25 up-regulation after anti-CD3 stimulation. Anti-CD3 treatment activated Akt and Erk1/2 signaling pathways as proven using specific inhibitors, and IL-7 further enhanced both signaling pathways. The close association of IL-7Rα with CD3ζ in the pre-TCR complex was illustrated through live imaging confocal fluorescence microscopy. These results demonstrate a direct and cooperative role of IL-7 in pre-TCR signaling. 相似文献
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Hung-Lin Chen Carey Fei Li Ani Grigorian Wenqiang Tian Michael Demetriou 《The Journal of biological chemistry》2009,284(47):32454-32461
T cell receptor (TCR) signaling enhances β1,6GlcNAc-branching in N-glycans, a phenotype that promotes growth arrest and inhibits autoimmunity by increasing surface retention of cytotoxic T lymphocyte antigen-4 (CTLA-4) via interactions with galectins. N-Acetylglucosaminyltransferase V (MGAT5) mediates β1,6GlcNAc-branching by transferring N-acetylglucosamine (GlcNAc) from UDP-GlcNAc to N-glycan substrates produced by the sequential action of Golgi α1,2-mannosidase I (MIa,b,c), MGAT1, α1,2-mannosidase II (MII, IIx), and MGAT2. Here we report that TCR signaling enhances mRNA levels of MIa,b,c and MII,IIx in parallel with MGAT5, whereas limiting levels of MGAT1 and MGAT2. Blocking the increase in MI or MII enzyme activity induced by TCR signaling with deoxymannojirimycin or swainsonine, respectively, limits β1,6GlcNAc-branching, suggesting that enhanced MI and MII activity are both required for this phenotype. MGAT1 and MGAT2 have an ∼250- and ∼20-fold higher affinity for UDP-GlcNAc than MGAT5, respectively, and increasing MGAT1 expression paradoxically inhibits β1,6GlcNAc branching by limiting UDP-GlcNAc supply to MGAT5, suggesting that restricted changes in MGAT1 and MGAT2 mRNA levels in TCR-stimulated cells serves to enhance availability of UDP-GlcNAc to MGAT5. Together, these data suggest that TCR signaling differentially regulates multiple N-glycan-processing enzymes at the mRNA level to cooperatively promote β1,6GlcNAc branching, and by extension, CTLA-4 surface expression, T cell growth arrest, and self-tolerance. 相似文献
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T cells absorb nanometric membrane vesicles, prepared from plasma membrane of antigen presenting cells, via dual receptor/ligand interactions of T cell receptor (TCR) with cognate peptide/major histocompatibility complex (MHC) plus lymphocyte function-associated antigen 1 (LFA-1) with intercellular adhesion molecule 1. TCR-mediated signaling for LFA-1 activation is also required for the vesicle absorption. Exploiting those findings, we had established a high throughput screening (HTS) platform and screened a library for isolation of small molecules inhibiting the vesicle absorption. Follow-up studies confirmed that treatments (1 hour) with various mitochondrial antagonists, including a class of anti-diabetic drugs (i.e., Metformin and Phenformin), resulted in ubiquitous inhibition of the vesicle absorption without compromising viability of T cells. Further studies revealed that the mitochondrial drug treatments caused impairment of specific membrane-proximal TCR signaling event(s). Thus, activation of Akt and PLC-γ1 and entry of extracellular Ca2+ following TCR stimulation were attenuated while polymerization of monomeric actins upon TCR triggering progressed normally after the treatments. Dynamic F-actin rearrangement concurring with the vesicle absorption was also found to be impaired by the drug treatments, implying that the inhibition by the drug treatments of downstream signaling events (and the vesicle absorption) could result from lack of directional relocation of signaling and cell surface molecules. We also assessed the potential application of mitochondrial antagonists as immune modulators by probing effects of the long-term drug treatments (24 hours) on viability of resting primary T cells and cell cycle progression of antigen-stimulated T cells. This study unveils a novel regulatory mechanism for T cell immunity in response to environmental factors having effects on mitochondrial function. 相似文献
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《Cell cycle (Georgetown, Tex.)》2013,12(3):247-249
Primordial germ cells (PGCs) give rise to sperms and eggs. Their development is crucial to species propagation and has to be precisely controlled. Studies in several model organisms have identified many genes involved in the specification and guided migration of PGCs. However, the mechanisms governing the behaviors of this unique type of cells remain to be investigated. Interestingly, PGCs share certain cellular properties with metastasizing cancer cells including proliferation, invasion of other tissues, survival, and migration. Recently we have shown that in Drosophila the receptor tyrosine kinase Torso activates both STAT and Ras during the early phase of PGC development. In later stages, activation of both STAT and Ras, likely by other molecules, is required continuously for PGC migration. The requirement for RTK suggests molecular conservation between flies and mice in PGC development and also suggests that germ cells and cancer cells share certain intracellular signaling strategies. 相似文献
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Sean Ryan Susamma Verghese Nicholas L. Cianciola Calvin U. Cotton Cathleen R. Carlin 《Molecular biology of the cell》2010,21(15):2732-2745
Sorting and maintenance of the EGF receptor on the basolateral surface of renal epithelial cells is perturbed in polycystic kidney disease and apical expression of receptors contributes to severity of disease. The goal of these studies was to understand the molecular basis for EGF receptor missorting using a well-established mouse model for the autosomal recessive form of the disease. We have discovered that multiple basolateral pathways mediate EGF receptor sorting in renal epithelial cells. The polycystic kidney disease allele in this model, Bicc1, interferes with one specific EGF receptor pathway without affecting overall cell polarity. Furthermore one of the pathways is regulated by a latent basolateral sorting signal that restores EGF receptor polarity in cystic renal epithelial cells via passage through a Rab11-positive subapical compartment. These studies give new insights to possible therapies to reconstitute EGF receptor polarity and function in order to curb disease progression. They also indicate for the first time that the Bicc1 gene that is defective in the mouse model used in these studies regulates cargo-specific protein sorting mediated by the epithelial cell specific clathrin adaptor AP-1B. 相似文献
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Caveolae orchestrate the dominant placental angiogenic growth factor fibroblast growth factor 2 (FGF2) signaling primarily via FGF receptor 1 (FGFR1) in placental artery endothelial cells; however, how the proximal FGF2/FGFR1 signaling is organized in the caveolae is obscure. We have shown in the present study that the FGFR substrate 2alpha (FRS2alpha) is physically associated with FGFR1, and both are targeted to the caveolae via interaction with caveolin-1 in ovine fetoplacental artery endothelial cells. Treatment with FGF2 rapidly stimulated time- and concentration-dependent FRS2alpha tyrosine phosphorylation and recruited the cytosolic growth factor receptor-bound protein 2 (GRB2)-GRB2-associated binding protein 1 (GAB1) complex to the caveolae, where they formed a ternary complex with FRS2alpha. Disruption of caveolae by cholesterol depletion with methyl-beta-cyclodextrin inhibited FGF2-induced FRS2alpha tyrosine phosphorylation, and it blocked the FGF2-induced recruitment of GRB2 and GAB1 to the caveolae and formation of the FRS2alpha-GRB2-GAB1 complex in the caveolae, as well as activation of the PI3K/AKT1 and MAPK1/2 pathways. Thus, these findings have demonstrated that the proximal fibroblast growth factor (FGF2/FGFR1) signaling is compartmentalized in the placental endothelial caveolae via the FGFR substrate 2α that mediates formation of a FRS2α-GRB2-GAB1 complex. 相似文献
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Christina Ketchum Heather Miller Wenxia Song Arpita Upadhyaya 《Biophysical journal》2014,106(1):26-36
Antigen binding to the B cell receptor (BCR) induces receptor clustering, cell spreading, and the formation of signaling microclusters, triggering B cell activation. Although the biochemical pathways governing early B cell signaling have been well studied, the role of the physical properties of antigens, such as antigen mobility, has not been fully examined. We study the interaction of B cells with BCR ligands coated on glass or tethered to planar lipid bilayer surfaces to investigate the differences in B cell response to immobile and mobile ligands. Using high-resolution total internal reflection fluorescence (TIRF) microscopy of live cells, we followed the movement and spatial organization of BCR clusters and the associated signaling. Although ligands on either surface were able to cross-link BCRs and induce clustering, B cells interacting with mobile ligands displayed greater signaling than those interacting with immobile ligands. Quantitative analysis revealed that mobile ligands enabled BCR clusters to move farther and merge more efficiently than immobile ligands. These differences in physical reorganization of receptor clusters were associated with differences in actin remodeling. Perturbation experiments revealed that a dynamic actin cytoskeleton actively reorganized receptor clusters. These results suggest that ligand mobility is an important parameter for regulating B cell signaling. 相似文献
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Antigen binding to the B cell receptor (BCR) induces receptor clustering, cell spreading, and the formation of signaling microclusters, triggering B cell activation. Although the biochemical pathways governing early B cell signaling have been well studied, the role of the physical properties of antigens, such as antigen mobility, has not been fully examined. We study the interaction of B cells with BCR ligands coated on glass or tethered to planar lipid bilayer surfaces to investigate the differences in B cell response to immobile and mobile ligands. Using high-resolution total internal reflection fluorescence (TIRF) microscopy of live cells, we followed the movement and spatial organization of BCR clusters and the associated signaling. Although ligands on either surface were able to cross-link BCRs and induce clustering, B cells interacting with mobile ligands displayed greater signaling than those interacting with immobile ligands. Quantitative analysis revealed that mobile ligands enabled BCR clusters to move farther and merge more efficiently than immobile ligands. These differences in physical reorganization of receptor clusters were associated with differences in actin remodeling. Perturbation experiments revealed that a dynamic actin cytoskeleton actively reorganized receptor clusters. These results suggest that ligand mobility is an important parameter for regulating B cell signaling. 相似文献
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T细胞抗原受体(T ceIl receptor,TCR)是T细胞表面关键的受体分子。TCR特异性地识别各种多肽抗原并通过胞内区ITAM磷酸化传递抗原刺激信号,进而引发T细胞的免疫效应。TCR的活性异常将会导致自身免疫病和免疫缺陷病的发生。对于TCR结构和功能的深入研究有助于我们更好地理解免疫反应的分子机理,从而为相关免疫疾病的预防和治疗提供重要的理论依据。该文对TCR的分类、基因重排机制、受体组装方式及其结构基础、TCR对抗原的识别以及活化机制等方面的研究成果进行了总结,综述了近几年来的最新研究进展。 相似文献
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Estefanía Moreno Clara Andradas Mireia Medrano María M. Caffarel Eduardo Pérez-Gómez Sandra Blasco-Benito María Gómez-Ca?as M. Ruth Pazos Andrew J. Irving Carme Lluís Enric I. Canela Javier Fernández-Ruiz Manuel Guzmán Peter J. McCormick Cristina Sánchez 《The Journal of biological chemistry》2014,289(32):21960-21972
The G protein-coupled receptors CB2 (CB2R) and GPR55 are overexpressed in cancer cells and human tumors. Because a modulation of GPR55 activity by cannabinoids has been suggested, we analyzed whether this receptor participates in cannabinoid effects on cancer cells. Here we show that CB2R and GPR55 form heteromers in cancer cells, that these structures possess unique signaling properties, and that modulation of these heteromers can modify the antitumoral activity of cannabinoids in vivo. These findings unveil the existence of previously unknown signaling platforms that help explain the complex behavior of cannabinoids and may constitute new targets for therapeutic intervention in oncology. 相似文献
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Chaohong Liu Xiaoming Bai Junfeng Wu Shruti Sharma Arpita Upadhyaya Carin I. M. Dahlberg Lisa S. Westerberg Scott B. Snapper Xiaodong Zhao Wenxia Song 《PLoS biology》2013,11(11)
Negative regulation of receptor signaling is essential for controlling cell activation and differentiation. In B-lymphocytes, the down-regulation of B-cell antigen receptor (BCR) signaling is critical for suppressing the activation of self-reactive B cells; however, the mechanism underlying the negative regulation of signaling remains elusive. Using genetically manipulated mouse models and total internal reflection fluorescence microscopy, we demonstrate that neuronal Wiskott–Aldrich syndrome protein (N-WASP), which is coexpressed with WASP in all immune cells, is a critical negative regulator of B-cell signaling. B-cell–specific N-WASP gene deletion causes enhanced and prolonged BCR signaling and elevated levels of autoantibodies in the mouse serum. The increased signaling in N-WASP knockout B cells is concurrent with increased accumulation of F-actin at the B-cell surface, enhanced B-cell spreading on the antigen-presenting membrane, delayed B-cell contraction, inhibition in the merger of signaling active BCR microclusters into signaling inactive central clusters, and a blockage of BCR internalization. Upon BCR activation, WASP is activated first, followed by N-WASP in mouse and human primary B cells. The activation of N-WASP is suppressed by Bruton''s tyrosine kinase-induced WASP activation, and is restored by the activation of SH2 domain-containing inositol 5-phosphatase that inhibits WASP activation. Our results reveal a new mechanism for the negative regulation of BCR signaling and broadly suggest an actin-mediated mechanism for signaling down-regulation. 相似文献
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M. Lia Palomba Kelly Piersanti Carly G. K. Ziegler Hugo Decker Jesse W. Cotari Kurt Bantilan Ivelise Rijo Jeff R. Gardner Mark Heaney Debra Bemis Robert Balderas Sami N. Malek Erlene Seymour Andrew D. Zelenetz Marcel R. M. van den Brink Grégoire Altan-Bonnet 《PloS one》2014,9(1)