Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10721 (c-kit)
 6,575 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Products of the ras gene family, termed p21ras, are GTP-binding proteins that have been implicated in signal transduction via receptors encoding tyrosine kinase domains. Recent findings have defined a superfamily of hemopoietin receptors that includes receptors for a number of interleukins and colony-stimulating factors. The intracellular portions of these receptors show only restricted homologies, have no tyrosine kinase domain, and provide no clues to the mode of signal transduction. However, in most cases the factors stimulate tyrosine phosphorylation. We demonstrate here that ligand-induced activation of the interleukin (IL)-2, IL-3, IL-5, and granulocyte-macrophage colony-stimulating factor receptors resulted in activation of p21ras in various hemopoietic cell lines. The only cytokine tested that binds to a hemopoietin receptor and that did not activate p21ras was IL-4. Activation of p21ras was also observed in response to Steel factor, which stimulates the endogenous tyrosine kinase activity of the c-kit receptor, as well as with phorbol esters, which activate protein kinase C. Experiments with protein kinase inhibitors implicated tyrosine kinase activity, but not protein kinase C activity, as the upstream signal in p21ras activation via these growth factor receptors. Attempts to demonstrate tyrosine phosphorylation of the p21ras GTPase-activating protein (GAP) were negative, suggesting that phosphorylation of GAP may not be the major mechanism for regulation of p21ras activity by tyrosine kinases.
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PMID:p21ras activation via hemopoietin receptors and c-kit requires tyrosine kinase activity but not tyrosine phosphorylation of p21ras GTPase-activating protein. 137 79

The "stromal" or adherent cells of long-term murine Dexter explant bone marrow cultures provide the best in vitro model of the bone marrow microenvironment. Colony-stimulating factor-1 (CSF-1) is produced constitutively by these cells and is easily detected, but most investigators have not found constitutive production of the other hemolymphopoietic cytokines. We have previously reported the detection of granulocyte-macrophage-CSF (GM-CSF) in murine stromal cultures and its induction by the lectin Pokeweed mitogen. The present studies analyzing stromal cytokine messenger RNA (mRNA) production by standard Northern blot analysis show constitutive production of mRNAs for CSF-1, GM-CSF, granulocyte-CSF (G-CSF), c-kit ligand (KL), and interleukin-6 (IL-6), but not IL-3, IL-4, or IL-5 by 3-week irradiated or nonirradiated murine Dexter stromal cells. Exposure of stromal cells to Pokeweed mitogen or IL-1 16 hours before RNA harvest induces the messages for GM-CSF, G-CSF, KL, and IL-6, but not IL-3, IL-4, IL-5, or CSF-1. Polymerase chain reaction amplification of cDNA made with reverse transcriptase from stromal RNA using two separate sets of IL-3-specific primers shows the presence of IL-3 message in irradiated stromal cells, which is only detectable with this more sensitive technique. The factor-dependent cell lines FDC-P1 and 32D are supported by the stromal cells without the addition of exogenous growth factors, demonstrating a cytokine activity in these cultures that is inhibited by the addition of anti-IL-3 or anti-GM-CSF antibodies. These data indicate that murine Dexter stromal cells constitutively produce CSF-1, GM-CSF, G-CSF, IL-6, KL, and IL-3. This growth factor production could explain the support of granulocyte, macrophage, and megakaryocyte production and stem cell maintenance in Dexter-type long-term murine bone marrow cultures.
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PMID:Biologic significance of constitutive and subliminal growth factor production by bone marrow stroma. 137 43

The clinical symptoms of allergy are caused by cellular (IgE-triggered) responses to an allergen. Effector cells of allergy include eosinophil and basophil granulocytes, as well as tissue mast cells. Growth and accumulation, as well as IgE-dependent and independent functions of these cells are regulated by distinct proteohormones and peptides. The hemopoietic cytokines IL-3 (interleukin-3), IL-5 and GM-CSF (granulocyte-macrophage colony-stimulating factor) are involved in the regulation of basophils (and eosinophils), whereas the ligand for c-kit, SCF (stem cell factor) is a mast cell-specific agonist. Basophils and mast cells express high-affinity IgE-binding sites. Allergen binding to IgE on mast cells and basophils, and consecutive cross-linking of IgE receptors is followed by production and/or secretion of inflammatory mediator substances. Specific activation and deactivation of mast cells/basophils in vitro has been demonstrated by use of recombinant cytokines and allergens, and specific haptens or by use of novel drugs, and should lead to epitope-specific diagnosis and better management of allergic diseases in the future.
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PMID:[Effector cells in allergy: biological principles and new pharmacologic concepts]. 750 62

Activation of phosphatidylinositol (PI) 3-kinase is a common sequel to tyrosine kinase activation and appears to be essential for tyrosine kinases to induce proliferation. Since multiple hemopoietic growth factors activate tyrosine kinases, we investigated whether these growth factors activate PI 3-kinase. We show that interleukin-3 (IL-3), interleukin-4 (IL-4), interleukin-5 (IL-5), granulocyte-macrophage colony stimulating factor (GM-CSF), and steel factor (SLF) all activate PI 3-kinase. These cytokines increased the amount of PI 3-kinase activity that could be immunoprecipitated with anti-phosphotyrosine antibodies from the MC-9 mast cell line or from the hemopoietic progenitor cell line FDC-P1. Increases in this assay frequently correlate with PI 3-kinase activation in vivo. To determine directly whether these factors activate PI 3-kinase in vivo, we measured the levels of 3-phosphorylated inositol phospholipids in intact 32P-labeled MC-9 cells. IL-3, IL-4, IL-5, GM-CSF, and SLF all caused increased synthesis of the PI 3-kinase products phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate with a relative potency of SLF >> IL-3 > IL-5, GM-CSF > IL-4. In contrast, IL-4 caused the largest increase in the in vitro anti-phosphotyrosine immune complex PI 3-kinase assay. Thus, the in vitro assay does not accurately reflect in vivo activation of PI 3-kinase. Cytokine treatment did not stimulate tyrosine phosphorylation of either the 85-kDa regulatory subunit or the 110-kDa catalytic subunit of PI 3-kinase and is therefore not required for activation of PI 3-kinase by these factors. Cytokine treatment did induce PI 3-kinase to associate with other tyrosine-phosphorylated proteins in a cytokine-specific manner. PI 3-kinase associated with c-kit after SLF stimulation, a 170-kDa protein after IL-4 stimulation, and a 70-kDa protein after treatment with IL-3 or GM-CSF. Thus, multiple hemopoietic growth factors that act through different types of receptors activate PI 3-kinase in vivo and induce factor-specific interactions of PI 3-kinase with other tyrosine-phosphorylated proteins.
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PMID:Multiple cytokines activate phosphatidylinositol 3-kinase in hemopoietic cells. Association of the enzyme with various tyrosine-phosphorylated proteins. 750 38

Human tumors can constitutively express cytokines and growth factors, but the extent of this expression has not been investigated. Using 44 different probes to cytokines, growth factors, and their receptors, we tested 21 melanoma and 5 melanocyte cultures for RNA transcript expression by reverse transcriptase-polymerase chain reaction. With 30 amplification cycles, expression of the cytokines interleukin (IL)-1 beta, IL-6, leukemia inhibitory factor (LIF), IL-7, gro alpha, IL-8 and the p35 chain of IL-12 was detected in more than 60% of melanomas. Concomitant receptors for IL-6 and IL-7 were also detected. IL-1 alpha, IL-5, Rantes, IL-10, interferon (IFN)-beta, tumor-necrosis factor (TNF)-alpha, G-colony-stimulating factor (CSF) and GM-CSF were expressed at lower levels. Melanocytes showed greatly reduced cytokine RNA transcripts, and only gro alpha was consistently detected. No expression of IL-2, IL-3, IL-4, IL-9, the p40 chain of IL-12, IFN-alpha or IFN-gamma RNA transcripts was detected in melanomas or melanocytes. The growth factors expressed by melanomas and, after further signal amplification, by melanocytes were transforming growth factor (TGF)-alpha, epidermal growth factor (EGF), TGF-beta, endothelial-cell growth factor (ECGF), basic-fibroblast growth factor (bFGF), nerve growth factor (NGF) and steel. The receptors EGFR, FGFR, NGFRp70 and c-kit were also expressed by melanomas and melanocytes. These results point to new possible autocrine and paracrine pathways in melanoma biology.
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PMID:Expression of cytokine/growth factors and their receptors in human melanoma and melanocytes. 750 78

Pluripotent hematopoietic stem cells (PHSCs) were highly enriched from mouse bone marrow by counterflow centrifugal elutriation, lineage subtraction, and fluorescence-activated cell sorting based on high c-kit receptor expression (c-kitBR). We used reverse transcriptase polymerase chain reaction to assay the c-kitBR subset and the subsets expressing low (c-kitDULL) and no (c-kitNEG) c-kit receptor for expression of mRNA encoding hematopoietic growth factor receptors and transcription factors. The c-kitBR cells had approximately 3.5-fold more c-kit mRNA than unfractionated bone marrow cells. The c-kitDULL cells had 47-58% of the c-kit mRNA found in c-kitBR cells and the c-kitNEG cells had 4-9% of the c-kit mRNA present in c-kitBR cells. By comparing mRNA levels in c-kitBR cells (enriched for PHSCs) with those of unfractionated bone marrow, we demonstrated that c-kitBR cells contained low or undetectable levels of mRNA for c-fms, granulocyte colony-stimulating factor receptor, interleukin 5 receptor (IL-5R), and IL-7R. These same cells had moderate levels of mRNA for erythropoietin receptor, IL-3R subunits IL-3R alpha (SUT-1), AIC-2A, and AIC-2B, IL-6R and its partner gp-130, and the transcription factor GATA-1 and high levels of mRNA for transcription factors GATA-2, p45 NF-E2, and c-myb. We conclude from these findings that PHSCs are programmed to interact with stem cell factor, IL-3, and IL-6 but not with granulocyte or macrophage colony-stimulating factor. These findings also indicate that GATA-2, p45 NF-E2, and c-myb activities may be involved in PHSC maintenance or proliferation.
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PMID:Pluripotent hematopoietic stem cells contain high levels of mRNA for c-kit, GATA-2, p45 NF-E2, and c-myb and low levels or no mRNA for c-fms and the receptors for granulocyte colony-stimulating factor and interleukins 5 and 7. 753 77

Cross-linkage of Fc epsilon RI on human lung mast cells purified by affinity magnetic selection with monoclonal antibody YB5.B8 against c-kit (purity > 90%) expressed mRNA for multiple cytokines. There was no constitutive expression of interleukin (IL)-4 mRNA. Mast cell stimulation with anti-IgE induced IL-4 mRNA expression which appeared maximal at 2 h and waned slowly over the next 24 h. IL-5, IL-6, IL-8 and tumour necrosis factor (TNF)-alpha mRNA were constitutively expressed. Mast cell activation with anti-IgE led to an increase of IL-5 and TNF-alpha mRNA signals within 2 h and which persisted for at least 24-48 h. On the other hand, IL-6 and IL-8 mRNA expression were not affected by anti-IgE challenge.
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PMID:Multiple cytokine mRNA expression in human mast cells stimulated via Fc epsilon RI. 754 65

By using the reverse transcriptase (RT)-PCR and in situ hybridization we have studied the expression of mRNA for IL-5 and IL-4 in human lung mast cells induced by cross-linkage of high affinity Fc epsilon Rs. Lung mast cells were purified using affinity magnetic selection with mAb YB5.B8 against c-kit to achieve a final mast cell purity > 93%. Purified mast cells were precultured with stem cell factor (SCF) (10 ng/ml) and myeloma IgE (3 micrograms/ml) for 16 h before challenge with anti-IgE (1 or 10 micrograms/ml). IgE-dependent activation of lung mast cells caused expression of IL-5 mRNA, which was evident by 2 h and persisted for up to 48-72 h in all of 12 experiments, whereas IL-4 mRNA expression was of a shorter duration and was demonstrable in 6 of 13 experiments. We confirmed that mast cells, and not T cells, were the source of these cytokine messages by using reverse transcriptase-PCR in cell preparations containing known numbers of mast cells and T cells, in situ hybridization in enriched mast cell preparations, and double in situ hybridization-immunocytochemical staining. IL-5 mRNA expression did not require the pretreatment of cells with SCF, whereas expression of IL-4 mRNA seemed to require both anti-IgE and SCF. The strength of IL-5 mRNA signal was related to anti-IgE concentration. Immunoreactive IL-5 was detectable 8 h after anti-IgE challenge, and 10(6) mast cells generated a mean of 731 +/- 400 pg of IL-5 into the supernatant during 48-h culture, but no IL-4 product was detectable. These findings demonstrate the capacity of human lung mast cells to transcribe IL-4 and IL-5 after IgE-dependent activation and to synthesize and release immunoreactive IL-5.
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PMID:IgE-dependent expression of mRNA for IL-4 and IL-5 in human lung mast cells. 754 33

Leukemic cells from a patient with chronic myelocytic leukemia (CML) basophilic crisis were examined in an in vitro clonogenic assay using recombinant human hematopoietic growth factors to elucidate the proliferative and differentiative behaviors. More than 90% of the leukemic cells showed the morphologic characteristics of basophils and were positive for CD11b and CD13. The phenotype of the leukemic cells was different from that of mast cells. In the clonogenic assay using various recombinant growth factors, the leukemic cells were responsive to interleukin-3 (IL-3) and granulocyte-macrophage colony-stimulating factor (GM-CSF), but not to granulocyte-CSF (G-CSF), erythropoietin (Epo), or IL-4. IL-5 showed synergistic effects on colony formations induced by both IL-3 and GM-CSF. Transcripts of the GM-CSF receptor alpha chain gene were detected in the leukemic cells, but transcripts of the IL-4 receptor gene were not. Furthermore, c-kit and IL-7 receptor genes were expressed in the leukemic cells. Our results suggest that the differentiation pathway of basophils is different from that of mast cells, even though the receptor gene for stem cell factor (c-kit) was expressed on the basophilic leukemic cells, as it was on mast cells.
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PMID:Cellular characteristics of chronic myelocytic leukemia basophilic crisis cells: phenotype, responsiveness to and receptor gene expression for various kinds of growth factors and cytokines. 767 84

We have tested the histamine releasing properties and priming abilities of a wide range of recombinant or purified cytokines and growth factors on the basophils of 20 subjects (10 atopic and 10 nonatopic). We found that monocyte chemotactic and activating factor/monocyte chemoattractant protein-1 (MCAF/MCP-1), RANTES, human macrophage inflammatory protein-1 alpha and human inflammatory protein-1 beta, Connective tissue activating peptide III and Neutrophil Activating Peptide-2 (NAP-2) cause histamine release from basophils and are all members of the intercrine/chemokine family. MCAF/MCP-1 was as potent as anti-IgE or C5a and it is clearly the major contributor to histamine releasing factor activity. RANTES was the second major histamine releasing factor among the positive cytokines. Both MCAF/MCP-1 and RANTES are present in conditioned mononuclear cell media and can be separated using Mono Q anion exchange chromatography. We also demonstrated that RANTES has unusual chromatographic properties in spite of its isoelectric point of > 9.0 because it is largely found in peak-2 of the Mono Q column rather than peak-1 in which intercrines such as MCAF/MCP-1, IL-8, and connective tissue activating peptide III are found. All other cytokines and growth factors tested were negative, with the exception of IL-3, which caused histamine release in a subpopulation of subjects, and also primed basophils for release by anti-IgE. Other basophil primers for anti-IgE-dependent histamine release were IL-5, mast cell growth factor (c-kit ligand), and insulin-like growth factor II. Using specific neutralizing antibodies we have shown that MCAF/MCP-1, RANTES, and IL-3 contribute significantly to the activity found in mononuclear cell culture supernatants. Granulocyte-macrophage-CSF, IP-10, I-309, IL-7, IL-8, IL-9, IL-10, IL-11, IgE-binding factor, TNF-alpha, TGF-beta 1, fibroblast growth factor, epidermal growth factor, and endothelial cell growth factor were negative for direct histamine release and as primers of basophils. Our results indicate that cytokines belonging to the intercrine/chemokine family are major constituents of the activity known as "histamine releasing factor" found in MNC supernatants.
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PMID:Characterization of the human basophil response to cytokines, growth factors, and histamine releasing factors of the intercrine/chemokine family. 767 99


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