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)

Investigations of mast cell biology have often used immortalized cultured cells which are continuously proliferating. In vivo, however, only 2% or fewer tissue mast cells are actively dividing. We used aphidicolin, an inhibitor of DNA polymerase to induce a proliferative arrest of murine mast cells characterized by an inhibition of cell division and thymidine incorporation, with accumulation of cells in G1 and early S phase of the cell cycle. Uridine incorporation and cell viability were not significantly impaired. DNA synthesis and cell division both resumed rapidly upon removal of the drug. Morphometric analysis demonstrated that cell size, granule size, and number of granules per cell were all increased in aphidicolin-treated cells. Proliferative arrest also produced a 14-fold increase in cellular histamine content, but did not alter the proteoglycans synthesized by the cell. The level of c-myc mRNA was reduced in aphidicolin-arrested cells, but returned to the level observed in untreated cells within 1 hr of removal of the drug. In contrast, the constitutive steady-state RNA levels of tumour necrosis factor-alpha (TNF-alpha), B2-microglobulin, actin, and the c-Ha-ras and c-fes protooncogenes were not altered. Aphidicolin-induced proliferative arrest did not prevent the induction of TNF-alpha, interleukin-6 (IL-6) and c-fos genes in response to calcium ionophore. Both the magnitude and induction kinetics of these messages were similar in aphidicolin-treated and untreated cells. We conclude that proliferative arrest results in morphological and biochemical changes suggestive of cellular maturation, but inhibition of cell division alone is not sufficient to alter mast cell phenotype. Although optimal c-myc expression appears to require active proliferation, cytokine gene induction can occur in non-dividing cells. These data suggest that the proliferative quiescence of in vivo mast cells should not preclude their involvement in biological events via elaboration of multi-functional cytokines.
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PMID:Aphidicolin-induced proliferative arrest of murine mast cells: morphological and biochemical changes are not accompanied by alterations in cytokine gene induction. 138 41

Interleukin 3 (IL-3) is a T cell-derived lymphokine that supports the growth and development of hematopoietic cells. Tyrosine phosphorylation has been suggested to play an important role in IL-3-dependent cell proliferation. To test whether a growth factor receptor carrying a tyrosine kinase can be functional in IL-3 dependent cells, we used a retroviral vector to introduce the human EGF receptor into a murine IL-3-dependent pre-mast cell line, IC2. The EGF receptors expressed on the infected clones bind EGF with both high and low affinities. EGF stimulates the infected cells for a short term growth response. In the presence of IL-3 and EGF, infected clones differentiate into more mature mast cells characterized by increases in intracellular granulation and histamine content. This differentiation is reversible when EGF is removed. EGF induces tyrosine phosphorylation of several cellular proteins and the expression of oncogenes c-fos and c-myc, in a manner analogous to IL-3 stimulation. These results indicate that the EGF receptor is functional in the pre-mast IC2 cells; EGF can support short-term proliferation and activates the signals that induce cell differentiation. Thus, EGF receptor-expressing IC2 cells provide a unique cellular system for in vitro study of mast cell differentiation.
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PMID:EGF induces differentiation of an IL-3-dependent cell line expressing the EGF receptor. 253 Oct 81

We have constructed a transgenic mouse strain in which a mammary tumor virus LTR/c-myc fusion gene is anomalously expressed in a wide variety of tissues. The deregulated c-myc transgene, now glucocorticoid inducible, contributes to an increased incidence of a variety of tumors, including those of testicular, breast, lymphocytic (B cell and T cell), and mast cell origin. The deregulated gene does not, however, otherwise disturb cell proliferation, nor does it interfere with normal development in these animals. Moreover, since not all tissues that express the transgene develop neoplasms, these results begin to define the transforming spectrum of the c-myc oncogene. They also extend to several organ systems the notion that elements in addition to an activated c-myc gene are required to induce malignancy in the living organism.
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PMID:Consequences of widespread deregulation of the c-myc gene in transgenic mice: multiple neoplasms and normal development. 301 Dec 71

Using Northern blot analysis the expression of several proto-oncogenes was studied in established lines of mast cell precursors. Upon removal of interleukin-3 (IL-3) from the culture medium, factor-dependent cells stop dividing. During the first 7 h, however, normal amounts of total cellular mRNAs are maintained, and this is reflected in unchanged levels of several transcripts, such as actin, c-Ha-ras and c-fes. In contrast, within 1.5 h of IL-3 removal, the levels of c-myc and c-fos mRNAs decrease drastically and addition of IL-3 at that stage quickly induces back the levels found in actively growing cultures. In factor-independent cells, which proliferate actively even in the absence of IL-3, high levels of c-myc and c-fos transcripts are maintained in the absence of growth factor. In cells arrested by serum starvation, addition of 10% serum induces massive amounts of c-fos transcripts, but not of c-myc, and cell proliferation is not restored. The data suggest that the c-myc and c-fos proto-oncogenes play an important role in mediating the multiple effects of IL-3 on hemopoietic progenitor cells.
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PMID:Interleukin-3-dependent expression of the c-myc and c-fos proto-oncogenes in hemopoietic cell lines. 308 85

An interleukin-3 (IL-3) dependent mast cell line (MC) was infected with a recombinant retrovirus expressing the proto-oncogene c-myc and the drug selectable marker neo. Cells containing the transcriptionally activated c-myc gene displayed an increased growth rate in liquid culture and a higher cloning efficiency in soft agar when compared to control virus infected cells. All infected cells remained absolutely dependent on IL-3 for growth and were not tumorigenic in nude mice. Similar results were obtained with two additional IL-3 dependent cell lines, the mast cell 32D and the pre-B-cell Ea3. Thus, while constitutive expression of c-myc potentiates the response of mast cells to IL-3, it is not sufficient to eliminate their requirement for growth factors.
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PMID:Constitutive c-myc expression enhances the response of murine mast cells to IL-3, but does not eliminate their requirement for growth factors. 328 Oct 92

Five tumours, which arose in cats naturally or experimentally infected with feline immunodeficiency virus (FIV), were examined with molecular probes to establish tumour cell lineage and to screen for integrated viral sequences. Three of the tumours were classed as B-cell lymphomas on the basis of morphology, immunocytochemistry, rearrangement of immunoglobulin heavy chain genes and lack of rearrangement of T-cell receptor (TCR) beta-chain genes. Two of these B-cell tumours arose in specific pathogen-free (SPF) cats experimentally infected with FIV. One case of multi-centric lymphosarcoma came from a cat naturally infected with both FIV and feline leukaemia virus (FeLV). This tumour contained integrated FeLV proviral sequences and was judged to be of T-cell origin on the basis of TCR gene rearrangement. The fifth case was a mast cell tumour. Rearrangement of the c-myc locus was not found in any of the FIV-associated tumours but was shown to be present in a rare immunoblastic B-cell lymphoma which arose in an uninfected SPF cat. None of the FIV-associated tumours showed evidence of integrated FIV sequences by Southern blot hybridisation, despite isolation of infectious virus from in vitro cultures of tumour cells in I case. These results confirm that FIV-associated tumours can occur in the absence of FeLV and suggest that the role of FIV in lymphomagenesis is generally indirect.
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PMID:Molecular analysis of tumours from feline immunodeficiency virus (FIV)-infected cats: an indirect role for FIV? 770 53

Stem cell factor (SCF) and interleukin-3 (IL-3) both act on several target hematopoietic populations, including mast cells. We have isolated a unique murine mast cell line, B6M, that is phenotypically similar to immature mast cells. For B6M cells, IL-3 is a survival factor and alone does not stimulate proliferation. SCF can stimulate proliferation of B6M cells, and together IL-3 and SCF synergize to stimulate optimal proliferation and long-term growth. A sustained induction of c-myc is observed only in the presence of SCF (with or without IL-3). In B6M cells, both IL-3 and SCF stimulate phosphorylation of Shc and activation of the Ras, Raf-1, MAPK pathway. Interestingly, IL-3 plus SCF synergistically activate MAPK. IL-3, but not SCF, leads to activation of Jak 2 and Stat 5 and induces pim-1 expression. From these data, we suggest that the induction of pim-1 and c-myc is independently regulated. Furthermore, IL-3-stimulated activation of the Jak 2/Stat 5 pathway, induction of pim-1, and activation of the Ras/MAPK pathway are insufficient to mediate proliferation of B6M cells. The unusual IL-3 response of B6M cells provides a useful model to dissect signals required for IL-3-stimulated survival and proliferation.
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PMID:Signaling pathways activated in a unique mast cell line where interleukin-3 supports survival and stem cell factor is required for a proliferative response. 861 90

Mast cells develop when spleen cells of mice are cultured in the medium containing interleukin (IL)-3. Cultured mast cells (CMCs) show apoptosis when they are incubated in the medium without IL-3. We obtained CMCs from tg/tg mice that did not express the transcription factor encoded by the mi gene (MITF) due to the integration of a transgene at its 5' flanking region. MITF is a member of the basic-helix-loop-helix-leucine zipper (bHLH-Zip) protein family of transcription factors. We investigated the effect of MITF on the apoptosis of CMCs after removal of IL-3. When cDNA encoding normal MITF ((+)-MITF) was introduced into tg/tg CMCs with the retroviral vector, the apoptosis of tg/tg CMCs was significantly accelerated. The mutant mi allele represents a deletion of an arginine at the basic domain of MITF. The apoptosis of tg/tg CMCs was not accelerated by the introduction of cDNA encoding mi-MITF. The overexpression of (+)-MITF was not prerequisite to the acceleration of the apoptosis, as the apoptotic process proceeded faster in +/+ CMCs than in mi/mi CMCs. The Ba/F3 lymphoid cell line is also dependent on IL-3, and Ba/F3 cells show apoptosis after removal of IL-3. The c-myc gene encodes another transcription factor of the bHLH-Zip family, and the overexpression of the c-myc gene accelerated the apoptosis of Ba/F3 cells. However, the overexpression of (+)-MITF did not accelerate the apoptosis of Ba/F3 cells. The (+)-MITF appeared to play some roles for the acceleration of the apoptosis specifically in the mast cell lineage.
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PMID:Involvement of transcription factor encoded by the mouse mi locus (MITF) in apoptosis of cultured mast cells induced by removal of interleukin-3. 932 38

Translation is regulated predominantly by an interplay between cis elements at the 3' and 5' ends of mRNAs and trans-acting proteins. Cyclosporin A (CsA), a calcineurin antagonist and blocker of interleukin-2 (IL-2) transcription in T cells, was found to inhibit translation of IL-3 mRNA in autocrine mast cell tumor lines. The mechanism involved ribosome-associated poly(A) shortening and required an intact AU-rich element in the 3' untranslated region. FK506, another calcineurin inhibitor, shared the effect. The translational inhibition by CsA was specific to oncogenically induced lymphokines IL-3 and IL-4 but not to IL-6, c-jun, and c-myc, which are expressed in the nonmalignant precursor cells. Furthermore, no translational down-regulation of the mRNA was observed in IL-3-transfected precursor cells. These data suggest that translational silencing is associated with the tumor phenotype.
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PMID:Cyclosporin A promotes translational silencing of autocrine interleukin-3 via ribosome-associated deadenylation. 985 12

Gain-of-function mutations in the proto-oncogene c-kit that induce constitutive kinase activity of its product, KIT protein, are characteristic of human mast cell disease and are believed to play a central role in mast cell leukemia oncogenesis, proliferation and survival. Nuclear overexpression of the Wnt effector beta-catenin and deregulated beta-catenin nuclear signaling can promote malignant transformation in solid tumors and hematologic malignancies. However, a role for beta-catenin in mast cell leukemia has not been described. Nuclear accumulation of beta-catenin is upregulated by its tyrosine phosphorylation, a process that can be exacerbated by deregulated expression of oncogenic tyrosine kinases. Here, we investigated the relationship between activated KIT and beta-catenin signaling in mast cell leukemia. Beta-catenin was tyrosine-phosphorylated in cells with KIT activated by either gain-of-function mutation or incubation with the KIT ligand stem cell factor. Beta-catenin tyrosine phosphorylation depended on KIT activity but not on PI3K-AKT activation. Tyrosine phosphorylation of beta-catenin was associated with its nuclear localization and enhanced transcription of target genes c-myc and cyclin D1. Endogenous KIT and beta-catenin were found to associate in mast cell leukemia cells, and in vitro kinase assay demonstrated that active KIT phosphorylates tyrosine residues of beta-catenin directly. Aberrant beta-catenin-driven transcription caused by deregulated KIT may represent a significant new target for treatment of mast cell leukemia.
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PMID:KIT regulates tyrosine phosphorylation and nuclear localization of beta-catenin in mast cell leukemia. 1794 10


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