Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P15088 (mast cell)
 14,925 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The immunosuppressive drugs FK506 and cyclosporin A have an identical spectrum of activities with respect to IgE receptor (Fc epsilon RI)-mediated exocytosis from mast cells and T cell receptor-mediated transcription of IL-2. These findings suggest a common step in receptor-mediated signal transduction leading to exocytosis and transcription and imply that immunosuppressive drugs target specific signal transduction pathways, rather than specific cell types. This hypothesis is supported by studies on the effect of rapamycin on IL-3 dependent proliferation of the rodent mast cell line PT18. Rapamycin inhibits proliferation of PT18 cells, achieving a plateau of 80% inhibition at 1 nM. This inhibition is prevented in a competitive manner by FK506, a structural analogue of rapamycin. Proliferation of rat basophilic leukemia cells and WEHI-3 cells was also inhibited, at doses comparable to those shown previously to inhibit IL-2-dependent proliferation of cytotoxic T lymphocyte line (CTLL) cells. In contrast, proliferation of A-431 cells, a epidermoid cell line, was not affected by rapamycin. DNA histograms indicate that complexes formed between the rapamycin-FK506-binding protein (FKBP) and rapamycin arrest-proliferating PT18 cells in the G0/G1-phase. It is concluded that FKBP-rapamycin complexes may inhibit proliferative signals emanating from IL-3 receptors, resulting in growth arrest of cytokine-dependent, hematopoietic cells.
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PMID:The effect of the immunophilin ligands rapamycin and FK506 on proliferation of mast cells and other hematopoietic cell lines. 138 15

CD2 subserves both adhesion and signal transduction functions in T cells, thymocytes, and natural killer (NK) cells. In mature T lymphocytes, CD2-mediated signaling function apparently requires surface expression of T cell receptors (TCRs). In contrast, in CD2+ CD3- NK cells and thymocytes, signal transduction through CD2 is TCR independent. To resolve this paradox and characterize TCR-independent triggering mechanisms, we transfected a human CD2 cDNA into a murine mast cell line, C1.MC/57 (Fc epsilon RI+, Fc gamma RII+, Fc gamma RIII+), which is known to produce interleukin 6 (IL-6) as well as release histamine in response to crosslinking of Fc epsilon RI. In the CD2 transfectant, a combination of anti-T11(2) + anti-T11(3) monoclonal antibodies (mAbs) induced a rise in intracellular free calcium [( Ca2+]i), IL-6 production, and histamine release. As expected, no activation was mediated by the same mAbs in C1.MC/57. F(ab)'s fragments of the activatory combination of anti-T11(2) + anti-T11(3) mAbs induced IL-6 in the CD2-transfected mast cells, demonstrating an Fc gamma receptor ectodomain-independent triggering mechanism. In addition, either intact anti-T11(2) or anti-T11(3) IgG alone, which failed to induce [Ca2+]i mobilization in the transfectant, was able to induce IL-6 production. A mAb directed against both Fc gamma RII (previously denoted as Fc gamma RIIb) and Fc gamma RIII (previously denoted as Fc gamma RIIa) inhibits this induction. These results indicate that: (a) Ca2+ mobilization is not essential for IL-6 production; and (b) crosslinking of CD2 and Fc gamma receptors via intact anti-CD2 IgG stimulates IL-6 production. Thus, CD2-mediated IL-6 production occurs by both Fc receptor ectodomain-independent as well as Fc receptor ectodomain-dependent mechanisms in these nonlymphoid cells. Northern blot analysis demonstrates that although the mast cells do not express CD3 zeta or CD3 eta mRNA, they express Fc epsilon RI gamma mRNA. The latter is a known component of Fc gamma RIII as well as Fc epsilon RI, has significant homology to CD3 zeta/eta, and is thought to have a signal transduction function. In these mast cells, CD2 signaling machinery does not require CD3 zeta/eta and may be linked to the Fc epsilon RI gamma subunit. We predict that this subunit or a related structure may confer a TCR-independent signal transduction pathway upon CD2 in CD3- NK cells, thymocytes, and certain B lymphocytes.
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PMID:T cell receptor-independent CD2 signal transduction in FcR+ cells. 170 51

The high affinity receptor for IgE (Fc epsilon RI) found on mast cells and basophils is a tetrameric complex of a single alpha subunit, a single beta subunit, and two identical gamma subunits. The genes for the three subunits of mouse Fc epsilon RI have now been cloned from the mast cell line, PT18. When compared at the DNA level, the rat and mouse subunits are similarly conserved. However, at the protein level the homology between mouse and rat alpha is surprisingly low (71% identities) especially in the cytoplasmic regions (57% identities) which are of different length (25 and 20 residues, respectively). By contrast the beta and gamma are homogeneously conserved between mouse and rat (83 and 93% identities, respectively). The consensus amino acid sequence of the alpha subunit derived from three species (rat, mouse, and human) shows that the cytoplasmic tail diverges to the same extent as the leader peptide. Conversely, the transmembrane domain of the alpha is highly conserved and contains 10 consecutive residues that are identical. Comparisons between mouse Fc epsilon RI and other mouse proteins reveal regions of high homology between the alpha subunit and Fc gamma RIIa and between the gamma subunit and the zeta chain of the T cell receptor. Cells transfected with the alpha gene express the alpha subunit on their surface very inefficiently. Efficient expression is only achieved after co-transfection of the three rodent genes or of the human alpha gene together with the rodent gamma without apparent need for beta. The subunits are completely interchangeable upon transfection so that various chimeric mouse-rat-human receptors can be expressed.
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PMID:Complete structure of the mouse mast cell receptor for IgE (Fc epsilon RI) and surface expression of chimeric receptors (rat-mouse-human) on transfected cells. 252 50

To identify genes involved in signal transduction pathways that regulate T cell activation and development, murine fetal thymocytes were screened for expression of protein tyrosine kinase family members by the polymerase chain reaction. Using this approach, a non-receptor protein tyrosine kinase, txk, was identified and cloned. Tsk is expressed in thymocytes as early as fetal day 13.5 and its expression at the mRNA level continues throughout development. Txk transcripts are present in thymocytes, peripheral T cells and mast cell lines, but are not detectable in B cell macrophage/monocyte cell lines or in non-hematopoietic fetal or adult tissues. In both thymocytes and T cells, txk transcripts are down-regulated after activation with PMA and ionomycin, concanavalin A or T cell receptor cross-linking. Sequence analysis indicates that txk contains SH2, SH3 and kinase catalytic domains and belongs to the tec family of cytoplasmic protein tyrosine kinases which includes tec, itk and btk. Its unique N-terminus contains a proline-rich region, but unlike the other tec family members, does not contain a pleckstrin homology domain. The restricted expression pattern of txk and its regulation by T cell activation make it an excellent candidate for involvement in signal transduction during thymocyte development.
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PMID:Murine txk: a protein tyrosine kinase gene regulated by T cell activation. 754 61

The late-phase of allergic asthma is characterized by infiltration of the airway with eosinophils within 6 h of mast cell activation. Pro-eosinophilic/pro-allergic (TH2) cytokines, originally described as T-lymphocyte products, have recently been ascribed to mast cells as well. To date, however, it is unknown if TH2 cytokine gene expression by the human mast cells is subject to receptor-mediated regulation analogous to that of T-cells, and if messenger RNA (mRNA) expression results in protein secretion occurring in a temporal context consistent with the late-phase response. We examined interleukin-4 (IL-4), IL-5, and IL-6 mRNA expression induced by anti-IgE activation of human lung explants as assessed using reverse transcription/polymerase chain reaction (RT-PCR). Anti-IgE stimulation resulted in rapid and sustained upregulation of IL-5 message, but did not have analogous effects on IL-4 or IL-6. Using quantitative-competitive PCR, we demonstrated that 100 ng of total cellular RNA from human lung contained 1 fg of IL-5 mRNA; this increased to 100 fg 4 h after anti-IgE activation. The source of the anti-IgE-enhanced IL-5 mRNA is likely the mast cell itself, as anti-CD3 activation of lung led to a dissimilar array of cytokine expression. In addition, human lung mast cells purified to near homogeneity expressed IL-5 mRNA after activation, as shown by both RT-PCR and in situ hybridization. In both lung fragments and purified human lung mast cells, the modulation of IL-5 mRNA expression preceded the secretion of IL-5 protein, detected as early as 4 h after activation. Neither isolated purified mast cells nor purified peripheral blood T cells could be induced to secrete detectable amounts of IL-5 protein when activated only with antibodies against IgE or CD3-T cell receptor complex, respectively. However, mast cells (n = 4) and T cells (n = 6) cultured at comparable concentrations (4 x 10(6)/ml) activated through their respective antigen receptors in the presence of phorbol ester yielded comparable IL-5 production (253 +/- 126 pg/ml versus 183 +/- 75 pg/ml, mean +/- SE). We conclude that mast cells are analogous to T cells in the requirement of co-stimuli for the production of IL-5 protein. Moreover, the rapid kinetics of IgE-mediated IL-5 transcription and protein elaboration are consistent with a primary role for mast cell activation directly leading to late-phase airway eosinophilia.
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PMID:Human lung mast cell IL-5 gene and protein expression: temporal analysis of upregulation following IgE-mediated activation. 757 4

Members of the Immunoglobulin Superfamily (Ig) present in the surface of rodent mast cells include the high affinity IgE receptor (Fc epsilon RI), the low affinity receptors for the Fc portion of IgG, the Fc gamma RII family and Fc gamma RIII as well as the recently cloned gp49 family that includes three members gp49A, gp49B1 and gp49B2. Fc epsilon RI and Fc gamma RIII are members of the multi-chain immune recognition receptor (MIRR) family since they possess a multimeric structure in which the signal transducing chains (gamma chains) contain six acids that conform the Antigen Homology Receptor 1 Motif (ARH1M), also present in the T cell receptor (TCR) transducing chains. gp49B1, gp49B2 and the FC gamma R family are monomeric chains that also contain the partial of full AHR1M motif in their cytoplasmic domain indicating the capability for signal transduction through tyrosine phosphorylation and the possibility of cell activation with mediator (s) or cytokine (s) release. Distribution of the Fc gamma R receptors and gp49 family members varies in the different stages of mast cell differentiation and maturation.
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PMID:Surface makers for mast cell subtypes: low affinity IgG receptors and gp49 family. 803 57

We demonstrate using primary mast cell cultures derived from wild-type and CD45-deficient mice that mast cell triggering through the high-affinity immunoglobulin E (IgE) receptor requires the cell surface tyrosine phosphatase CD45. Unlike wild-type cells, cross-linking of surface-bound IgE in mast cells deficient in CD45 does not induce degranulation. Degranulation in these mutant cells does occur after treatment with the calcium ionophore A23187 indicating that the degranulation machinery is intact in these cells. We also demonstrate that the tyrosine phosphatase inhibitors orthoVanadate and perVanadate inhibit degranulation in wild-type mast cells, as does cross-linking of CD45 by anti-CD45 antibodies. Finally, we show that CD45-deficient mice are resistant to IgE-dependent systemic anaphylaxis. These results show that, like the T cell receptor and the antigen receptor on B cells, there is an absolute requirement for CD45 in signaling via the high affinity IgE receptor, expanding the number of receptors for which CD45 is an essential component.
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PMID:Leukocyte common antigen (CD45) is required for immunoglobulin E-mediated degranulation of mast cells. 804 27

The gamma subunit of immunoglobulin Fc receptors is an essential component of the high-affinity receptor for IgG (Fc gamma RIII) and is associated with the high-affinity receptor for IgG (Fc gamma RI) and the T cell receptor-CD3 complex. It is required for both receptor assembly and signal transduction. Targeted disruption of this subunit results in immunocompromised mice. Activated macrophages from gamma chain-deficient mice unexpectedly lack the ability to phagocytose antibody-coated particles, despite normal binding. Defects in NK cell-mediated antibody-dependent cytotoxicity and mast cell-mediated allergic responses are evident in these animals, establishing the indispensable role of FcRs in these responses. However, loss of gamma chain does not appear to perturb T cell development, since both thymic and peripheral T cell populations appear normal. These mice thus represent an important tool for evaluating the role of these receptors in humoral and cellular immune responses.
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PMID:FcR gamma chain deletion results in pleiotrophic effector cell defects. 831 72

Genes encoding T-cell-receptor alpha/delta chains, neutrophil cathepsin G, and lymphocyte CGL/granzymes are closely linked on chromosomal band 14q11.2. The current work identifies the human mast cell chymase gene (CMA1) as the fourth protease in this cluster and maps the gene to within 150 kb of the cathepsin G gene. The gene order is centromere-T cell receptor alpha/delta-CGL-1/granzyme B-CGL-2/granzyme H-cathepsin G-chymase. Chymase and cathepsin G genes are shown to be cotranscribed in the human mast cell line HMC-1 and in U-937 cells. Other cells transcribe cathepsin G or CGL/granzyme genes, but not chymase genes, suggesting a capacity for independent regulation. Comparison of the 5' flank of the chymase gene with those of cathepsin G and CGL/granzymes reveals little overall homology. Only short regions of the 5' flanks of the human and murine chymase gene sequenced to date are similar, suggesting that they are more distantly related than human and rodent CGL-1/granzyme B, the flanks of which are highly homologous. The expression patterns and clustering of genes provide possible clues to the presence of locus control regions that orchestrate lineage-restricted expression of leukocyte and mast cell proteases.
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PMID:The human mast cell chymase gene (CMA1): mapping to the cathepsin G/granzyme gene cluster and lineage-restricted expression. 846 56

In order to investigate the functional similarities of the high affinity receptor for IgE (Fc epsilon RI) and the T cell receptor for antigen, we have developed a high efficiency polyethylene glycol-mediated fusion method to make somatic hybrids between cells from a mast cell line (RBL-2H3) and cells from T lymphoma cell lines (Jurkat and HPB-ALL). Using flow cytometry to select for the heterologously fused cells, we demonstrated that aggregation of the T cell receptor results in the efficient secretion of [3H]5-hydroxytryptamine from RBL cell-derived granules. In addition, both receptors mediate Ca2+ mobilization in the hybrid cells that is insensitive to inhibition by the protein kinase C activator phorbol-12-myristoyl-13-acetate (PMA). In contrast, Ca2+ mobilization caused by aggregation of Fc epsilon RI in the parent RBL cells is completely inhibited by PMA. The results indicate that these two different receptors for foreign antigen can substitute for each other to trigger responses in the hybrid cells that are unique to each cell type. The methodology employed has general utility for studying signal transduction mediated by mammalian cell surface receptors.
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PMID:Fc epsilon RI and the T cell receptor for antigen activate similar signalling pathways in T cell-RBL cell hybrids. 849 25


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