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)

Recent evidence suggests a critical role for Syk in mast cell activation upon high affinity IgE receptor (FcepsilonRI) aggregation. A rat basophilic leukemia cell line, RBL-2H3, expresses similar levels of two Syk isoforms that differ with respect to the presence of a 23-amino acid insert within the "linker" region located between the second Src homology 2 and the catalytic domain. Although they exhibit comparable intrinsic enzymatic activity, functional differences between the two isoforms are unknown. Here we report that the deleted Syk isoform can mediate signal transduction in RBL-2H3 cells. Aggregation of chimeric kinase, consisting of either form of Syk fused to the transmembrane and extracellular domains of guinea pig type II IgG Fc receptor, on RBL transfectants resulted in degranulation, release of leukotrienes, and enhanced gene expression of tumor necrosis factor-alpha. The chimeras as well as phospholipase C-gamma1 and Vav became tyrosine-phosphorylated upon aggregation of chimeras. We also found that both Syk isoforms from transiently transfected COS-7 cells were capable of binding to phosphorylated FcepsilonRI, and their kinase activities were similarly up-regulated in the presence of tyrosine-phosphorylated synthetic peptides based on the sequence of the gamma subunit of FcepsilonRI. Thus, these results establish that both isoforms of Syk can mediate signal transduction in mast cells and suggest that the 23-amino acid insert in the linker region of Syk may not be obligatory for FcepsilonRI signaling.
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PMID:Evidence for involvement of two isoforms of Syk protein-tyrosine kinase in signal transduction through the high affinity IgE receptor on rat basophilic leukemia cells. 960 11

The murine T1 gene encodes a membrane-bound glycoprotein (T1M) and a soluble variant (T1S) which represents the ectodomain of the receptor-type form. T1 is an orphan receptor belonging to the interleukin-1 receptor family. Its biological function is currently unknown. We analyze the expression of the two T1 proteins in mast cells and fibroblasts by using a set of monoclonal antibodies (MAb) that specifically recognize the extracellular portion of the T1 receptor. To generate anti-T1 MAbs, we immunized Lewis rats with a eukaryotically expressed chimeric protein consisting of the T1-receptor ectodomain fused to a human immunoglobulin domain. The two MAbs DJ4 and DJ8 were shown to specifically detect the murine T1M protein on the surface of primary IL-3-dependent bone marrow-derived mast cells as shown by flow cytometry and immunohistochemistry. Both antibodies were also capable of immunoprecipitating the membrane-associated 110-120 kDa T1M protein from mast cell lysates. In serum-stimulated but not in quiescent NIH3T3 fibroblasts, DJ4 and DJ8 MAbs detected both the soluble T1S protein as a 45-65 kDa band on SDS polyacrylamide gels as well as the membrane-bound 95 kDa T1M protein. The T1M protein in fibroblasts was less abundantly expressed and exhibited a lower molecular weight than the mast cell-produced T1M, probably as a consequence of different protein glycosylation. The MAbs described here represent highly specific reagents and valuable tools that should facilitate the establishment of the murine T1 protein expression pattern thus contributing to the solution of the question of its function.
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PMID:Expression analysis of the soluble and membrane-associated forms of the interleukin-1 receptor-related T1 protein in primary mast cells and fibroblasts. 962 50

Latexin, a carboxypeptidase A inhibitor, is expressed in a cell type-specific manner in both central and peripheral nervous systems in the rat. In the neocortex, a specific subpopulation of neurons in layers V and VI expresses latexin. In the primary sensory ganglia, the expression is restricted to smaller diameter neurons. As a first step to clarify regulatory mechanisms underlying cell type-specific expression of latexin, we have determined the organization of the rat latexin gene and analyzed its regulatory elements. The latexin gene spans approximately 5.8 kb, and consists of six exons and five introns. Three transcription initiation sites were mapped. The upstream region lacks typical TATA or CAAT boxes but has several GC-rich sites. To assess promoter activity, the luciferase reporter gene fused to the 5'-flanking region (6.4 kb) of the latexin gene was transiently transfected into several cell lines. Luciferase activity was 2-8 times higher in latexin-expressing cells (PC12) than non-expressing cells (NS20 and L6). Deletion analysis with PC12 cells revealed that a core promoter is located between nucleotide positions -261 and -201 relative to the A of the initiation codon. Nerve growth factor (NGF)-responsive element(s) is located between positions -518 and -262, in which AP-1, AP-2 and NF-kappaB binding sites are found. Furthermore, we demonstrate that a 1.3 kb genomic fragment containing the first intron has transcriptional enhancing activity in PC12 cells. These results suggest that up and downstream regulatory elements are involved in the control of cell type-specific expression of latexin.
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PMID:Genomic organization and regulatory elements of the rat latexin gene, which is expressed in a cell type-specific manner in both central and peripheral nervous systems. 1035 Jun 38

A simple method for the detection of endogenous histamine in rat peritoneal mast cells was evaluated using on-line mode in-capillary derivatization high-performance capillary electrophoretic (ICD-HPCE) techniques, which were previously developed by our group [S. Oguri et al., J. Chromatogr. A, 787 (1997) 253-260]. The method involves a suspension of peritoneal mast cells (1 x 10(6) cells/ml of saline) collected from a male Wistar rat (eight weeks of age), which are directly introduced into the capillary tube from the anodic end by hydrostatic injection (at 25 cm height, for 2-20 s). When a high-voltage potential (25 kV) is applied to the capillary, which is already filled with the run buffer containing both a lysing reagent (SDS, sodium dodecyl sulfate,) and a derivatizing reagent (OPA, o-phthalaldehyde; NAC, N-acetylcysteine), histamine in the mast cells was detected at high-sensitivity level without further procedures. During ICD-HPCE, the mast cells injected in the capillary were lysed with the lysing reagent, free histamine released from the cell was labeled with the derivatizing reagent, and its derivative was electromigrated, separated and detected with a fluorescence detector (excitation wavelength at 340 nm, emission wavelength at 450 nm) in a fused-silica capillary (75 cm x effective length x 50 microm I.D.). The run buffer used was a 20 mM phosphate-borate buffer (pH 10) containing 20 mM SDS, 2 mM OPA and 2 mM NAC. This method was also examined with regard to the possibility of its use for determination of histamine at the single mast cell level.
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PMID:Direct detection of endogenous histamine in rat peritoneal mast cells by in-capillary derivatization high-performance capillary electrophoresis. 1067 7

Mast cells stimulated with adriamycin at 4 degrees C underwent a unique exocytotic reaction. Rat peritoneal cells including mast cells were stimulated in vitro with adriamycin (100 micrograms/ml) for 0, 10, 30 or 60 sec and observed by transmission electron microscopy. Early changes could be observed after 10 sec stimulation and consisted in an approximately 5-fold increase (p < 0.001) of 0.05-0.2 micron diameter cytoplasmic vesicles. The Golgi apparatus showed signs of activation and vacuolization. From 10 to 30 sec, cytoplasmic vesicles fused with the perigranular membranes and with the membranes of developing secretory channels. At 60 sec, the number of vesicles and vacuoles diminished to nearly two-fold starting levels. The exocytotic reaction characteristically resulted in the formation of enormously dilated granular cavities. The secretory process appeared incomplete; after 60 sec, in fact, maximal histamine release was 20% and exocytosis could be found in approximately 30% of mast cells. Pre-incubation with vinblastine followed by adriamycin stimulation at 37 degrees C determined a dose-dependent inhibition of histamine release which was accompanied by the ultrastructural appearance of numerous 0.05-0.5 micron cytoplasmic vesicles and by signs of inhibited exocytosis. Our results support the concept that hyperstability of the cortical cytoskeleton coupled with microtubule perturbation would be responsible for the depressed pattern of mast cell exocytosis observed at 4 degrees C. Although stimulation at 4 degrees C induces a paradoxal secretory process, we believe that this approach may represent a useful model for understanding some basic mechanisms of exocytosis in mast cells.
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PMID:Effect of low temperature on mast cell exocytosis. Early cytoplasmic vesicle formation and the role of cytoskeleton. 1068 89

The 8p11 myeloproliferative syndrome (EMS) is associated with three translocations, t(8;13)(p11;q12), t(8;9)(p11;q33), and t(6;8)(q27;p11), that fuse unrelated genes (ZNF198, CEP110, and FOP, respectively) to the entire tyrosine kinase domain of FGFR1. In all cases thus far examined (n = 10), the t(8;13) results in an identical mRNA fusion between ZNF198 exon 17 and FGFR1 exon 9. To determine if consistent fusions are also seen in the variant translocations, we performed RT-PCR on four cases and sequenced the products. For two patients with a t(8;9), we found that CEP110 exon 15 was fused to FGFR1 exon 9. For two patients with a t(6;8), we found that FOP exon 5 (n = 1) or exon 7 (n = 1) was fused to FGFR1 exon 9. To determine if FGFR1 might be involved in other myeloid disorders with translocations of 8p, we developed a two-color FISH assay using two differentially labeled PAC clones that flank FGFR1. Disruption of this gene was indicated in a patient with a t(8;17)(p11;q25) and Ph-negative chronic myeloid leukemia in association with systemic malignant mast cell disease, a patient with acute myeloid leukemia with a t(8;11)(p11;p15), and two cases with T-cell lymphoma, myeloproliferative disorder, and marrow eosinophilia with a t(8;12)(p11;q15) and ins(12;8)(p11;p11p21), respectively. For the patient with the t(8;11), the chromosome 11 breakpoint was determined to be in the vicinity of NUP98. We conclude that 1) all mRNA fusions in EMS result in splicing to FGFR1 exon 9 but breakpoints in FOP are variable, 2) two-color FISH can identify patients with EMS, and 3) the t(8;17)(p11;q25), t(8;11)(p11;p15), t(8;12)(p11;q15), and ins(12;8)(p11;p11p21) are novel karyotypic changes that most likely involve FGFR1.
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PMID:Identification of four new translocations involving FGFR1 in myeloid disorders. 1155 Feb 83

Mast cells are one of the major effector cells in the pathogenesis of allergic diseases such as contact dermatitis. In the present study, ultrastructural features of mast cells in contact dermatitis were examined. Namely, the ear of IQI/Jic mice was topically applied with picryl chloride (PCL) at 4 (1st), 11 (2nd), 18 (3rd) and 25 days (4th) after the sensitization with PCL to the abdominal skin. The changes in the ear swelling responses, total serum IgE levels and histology including mast cell numbers were similar to those of previous reports by our research group (Ikeda et al. 2000; Jung et al. 2001). Ultrastructurally, after the 1st application, a close spacial relationship between mast cells and neutrophils and phagocytosis of mast cell granules by neutrophils were observed. Mast cells generally contained non-fused swollen granules filled with altered contents with low electron density and showed an extrusion of membrane-free granules through membrane pores. In addition, interestingly, a few mast cells secreted membrane-bound granules into the dermis without leaving cell membrane damage. After the 4th application when the number of mast cells prominently increased and the total serum IgE level was greatly elevated, in addition to mast cells showing typical anaphylactic degranulation, many mast cells probably in the recovery process from degranulation and several immature mast cells characterized by well-developed Golgi apparatus, many ribosomes and a few electron-dense secretory granules in the peripheral cytoplasm were also observed at the same time. The present results clarified the ultrastructural features of mast cells in the course of PCL-induced contact dermatitis in IQI/Jic mice.
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PMID:Ultrastructural features of mast cells in picryl chloride (PCL)-induced contact dermatitis in IQI/Jic mice. 1271 Jul 8

We have examined the trafficking of synaptotagmin (Syt) I and II in the mast cell line rat basophilic leukemia (RBL-2H3). We demonstrate that both Syt I and Syt II travel through the plasma membrane and require endocytosis to reach their final intracellular localization. However, N- or C-terminal tagging of Syt II, but not of Syt I, prevents its internalization, trapping the tagged protein at the plasma membrane. Furthermore, a chimeric protein comprising a tagged luminal domain of Syt II fused with the remaining domains of Syt I also localizes to the plasma membrane, whereas a chimera consisting of tagged luminal domain of Syt I fused with Syt II colocalizes with Syt I on secretory granules. We also show that endocytosis of both Syt I and Syt II is strictly dependent on O-glycosylation processing, whereby O-glycosylation mutants of either protein fail to internalize and remain at the plasma membrane. Our results indicate that the luminal domains of Syt I and Syt II govern their internalization capacity from the plasma membrane and identify O-glycosylation as playing a crucial role in Syt trafficking in non-neuronal secretory cells.
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PMID:O-glycosylation is essential for intracellular targeting of synaptotagmins I and II in non-neuronal specialized secretory cells. 1575 99

Mast cells play an important role at the early stages of immunological response to bacterial infections and parasite infestations. One of the major mast cell proinflammatory mediators is TNF-alpha. Mast cells are considered the only cells capable of storing TNF-alpha in cytoplasmic granules and rapidly releasing it upon activation. To determine what pathway is utilized to direct TNF-alpha to cytoplasmic granules and what motifs are responsible for the sorting process, we constructed a fusion protein covering the full sequence of TNF-alpha, N-terminally fused to enhanced green fluorescent protein (EGFP). In rodent mast cells, such protein was sorted to secretory granules, and this process was inhibited by both brefeldin A and monensin. Considering the relationship between lysosomes and secretory granules and following TNF-alpha sequence analysis, it was determined whether TNF-alpha is sorted through the mannose-6-phosphate receptor (MPR)-dependent pathway. We observed that ammonium chloride and tunicamycin blocked TNF-alpha-EGFP fusion protein delivery to secretory granules. In situ mutagenesis experiments confirmed the necessity of N-linked glycosylation for efficient sorting of TNF-alpha into rodent mast cell granules. In this work we established that TNF-alpha travels from the ER to mast cell granules via a brefeldin A- and monensin-sensitive route, utilizing the MPR-dependent pathway, although this dependency does not seem to be absolute.
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PMID:Efficient sorting of TNF-alpha to rodent mast cell granules is dependent on N-linked glycosylation. 1654 68

The powerful anti-inflammatory and immunosuppressive activities of IL-10 make it attractive for supplemental therapy in translational tolerance induction protocols. This is bolstered by reports of IL-10-mediated inhibition of innate immunity, association of human stem cell and nonhuman primate (NHP) islet allograft tolerance with elevated serum IL-10, and evidence that systemic IL-10 therapy enhanced pig islets survival in mice. IL-10 has not been examined as adjunctive immunosuppression in NHP. To enable such studies, we cloned and expressed rhesus macaque (RM) IL-10 fused to a mutated hinge region of human IgG1 Fc to generate IL-10/Fc(ala-ala). RM IL-10/Fc(ala-ala) was purified to approximately 98% homogeneity by affinity chromatography and shown to be endotoxin-free (<0.008 EU/microg protein). The biological activity of IL-10/Fc(ala-ala) was demonstrated by (1) costimulation of the mouse mast cell line, MC/9 proliferation in a dose-dependent fashion, (2) suppression of LPS-induced septic shock in mice and (3) abrogation of LPS-induced secretion of proinflammatory cytokines/chemokines in vitro and in vivo in NHP. Notably, RM IL-10/Fc(ala-ala) had significantly greater potency than human IL-10/Fc(ala-ala) and exhibited a circulating half-life of approximately 14 days. The availability of this reagent will facilitate definitive studies to determine whether supplemental therapy with RM IL-10/Fc(ala-ala) can influence tolerance outcomes in NHP.
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PMID:Cloning and characterization of recombinant rhesus macaque IL-10/Fc(ala-ala) fusion protein: a potential adjunct for tolerance induction strategies. 1798 Jun 15


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