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

Three monoclonal antibodies (MAbs) to the human c-kit receptor tyrosine kinase (P145c-kit), derived in independent laboratories, have been extensively used in studies of c-kit expression and the role of its ligand, steel factor (SLF), in hemopoiesis and mast cell differentiation and function. In this study, the relationship between the epitopes they identify, and their effects on SLF binding, receptor internalization, and signal transduction are compared. Epitope mapping studies carried out on the high P145c-kit-expressing cell line HEL-DR showed that SR-1 identifies an epitope independent of those bound by YB5.B8 and 17F11, while the latter two antibodies bound to distinct but interacting epitopes. SR-1 potently blocked the binding of SLF to P145c-kit on these cells and also on cells of the factor-dependent line MO7e. In contrast, YB5.B8 and 17F11 had minimal effects on ligand binding. Conversely, SLF partially blocked the binding of SR-1 and YB5.B8 to cells, while binding of 17F11 was actually enhanced by SLf on some target cells. Preincubation of HEL-DR and MO7e cells with MAbs prior to exposure to SLF revealed that 17F11 itself brought about partial down-regulation of P145c-kit and did not inhibit SLF-mediated down-regulation. SR-1 caused minimal down-regulation and inhibited SLF-mediated receptor internalization. YB5.B8 had minimal effects on either cell line in this assay. To determine whether the antibodies had any agonist activity, they were compared with SLF for their ability to bring about receptor phosphorylation in intact MO7e cells. All three antibodies induced detectable tyrosine phosphorylation with 17F11 being the most effective, while YB5.B8 was the least effective. Finally, the ability of the antibodies to influence the proliferation of the MO7e cells was examined. As expected, SR-1 potently inhibited the proliferative response to SLF, while 17F11 weakly inhibited and YB5.B8 had negligible effect. In the absence of SLF both 17F11 and YB5.B8 displayed very weak but reproducible agonist activity.
 ...
PMID:Epitope mapping and functional studies with three monoclonal antibodies to the c-kit receptor tyrosine kinase, YB5.B8, 17F11, and SR-1. 751 Feb 97

In this report we demonstrate that murine bone marrow cells cultured in either interleukin (IL)-3 or mast cell growth factor (MGF, also known as c-kit ligand and stem cell factor) differentially express cytokine genes. Bone marrow cells cultured in IL-3 differentiate and proliferate, taking on a mucosal mast cell-like phenotype. These cells express the IL-4 gene. Bone marrow cells cultured in MGF take on a connective tissue mast cell-like phenotype and possess transcripts for both of the subunits of the IL-12 cytokine. Bone marrow cells cultured in both IL-3 and MGF express the IL-4 gene at lower levels than that seen for the IL-3 culture alone, but do not possess IL-12 gene transcripts. The level of IL-12 subunit transcripts derived from the MGF-derived bone marrow cells was compared to that found in splenocytes and activated macrophages, the only cells in which IL-12 production has been previously documented. Both of the IL-12 subunit transcripts were found, compared to a beta-actin control, to be present within MGF-derived cells in the same if not higher quantities than the splenocyte or macrophage cultures. Mucosal mast cells have been previously implicated in the development of the T helper type 2 (TH2) T cell phenotype via their expression of IL-4. The finding that the MGF-derived connective tissue-like mast cells possess IL-12 transcripts suggests that the development of the TH1 T cell pathway may be positively influenced by this type of mast cell.
 ...
PMID:Preferential expression of interleukin-12 or interleukin-4 by murine bone marrow mast cells derived in mast cell growth factor or interleukin-3. 751 32

The c-kit receptor tyrosine kinase belongs to the PDGF/CSF-1/c-kit receptor subfamily. The kit-ligand, KL, also called steel factor, is synthesized from two alternatively spliced mRNAs as transmembrane proteins that can either be proteolytically cleaved to produce soluble forms of KL or can function as cell-associated molecules. The c-kit receptor kinase and KL are encoded at the white spotting (W) and steel (Sl) loci of the mouse, respectively. Mutations at both the W and the Sl locus cause deficiencies in gametogenesis, melanogenesis and hematopoiesis. The c-kit receptor is expressed in the cellular targets of W and Sl mutations, while KL is expressed in their microenvironment. In melanogenesis, c-kit is expressed in melanoblasts from the time they leave the neural crest and expression continues during embryonic development and in the melanocytes of postnatal animals. In gametogenesis c-kit is expressed in primordial germ cells, in spermatogonia, and in primordial and growing oocytes, implying a role at three distinct stages of gametogenesis. Many mutant alleles are known at W and Sl loci and their phenotypes vary in the degree of severity in the different cellular targets of the mutations. While many W and Sl alleles severely affect primordial germ cells (PGC), several mild Sl alleles have weak effects on PGCs and exhibit differential male or female sterility. Steel Panda (Sl(pan)) is a KL expression mutation in which KL RNA transcript levels are reduced in most tissues analyzed. In female Sl(pan)/Sl(pan) mice, ovarian follicle development is arrested at the one layered cuboidal stage as a result of reduced KL expression in follicle cells, indicating a role for c-kit in oocyte growth. Wsh is a c-kit expression mutation, which affects mast cells and melanogenesis. While the mast cell defect results from lack of c-kit expression, the pigmentation deficiency appears to stem from ectopic c-kit receptor expression in the somitic dermatome at the time of migration of melanoblasts from the neural crest to the periphery. It is proposed that the ectopic c-kit expression in Wsh mice affects early melanogenesis in a dominant fashion. The "sash" or white belt of Wsh/+ animals and some other mutant mice is explained by the varying density of melanoblasts along the body axis of wild-type embryos.
 ...
PMID:The kit-ligand (steel factor) and its receptor c-kit/W: pleiotropic roles in gametogenesis and melanogenesis. 751 81

We have previously reported a method of mast cell induction by long-term culture of mouse spleen cells without using exogenous mast cell growth factor (Z.-Q. Hu, T. Yoshida, and T. Shimamura, J. Immunol. Methods 149:173, 1992). Supernatants recovered from the long-term cultures contain endogenous interleukin 3 and soluble stem cell factor. These were assessed by the capacity of the recovered supernatants to foster the growth of a mast cell growth factor-dependent cell line and by neutralizing antibodies. Besides the soluble factors, cell-to-cell contacts mediated by membrane stem cell factor on splenic stromal cells and c-Kit receptors on mast cells also affect mast cell induction. Different lots of fetal calf serum (FCS) were examined to determine a possible trigger for cytokine production. FCS can be divided into mast cell-inducible and noninducible sera by this process. However, not all FCS lots contain mast cell growth factor. The mast cell-inducible lots contain lipopolysaccharide (LPS) confirmed by a Limulus assay. Polymyxin B can neutralize the mast cell induction activity. Non-mast cell-inducible FCS can be converted to inducible FCS by adding exogenous LPS. The results indicate that LPS as a trigger of cytokine production is responsible for mast cell induction.
 ...
PMID:Effect of lipopolysaccharide on mouse mast cell induction by a splenic cell culture system. 752 Apr 22

Mouse bone marrow (BM) was cultured in the presence of recombinant mouse (rm) interleukin-3 (IL-3), rmIL-4, rmIL-5, rmIL-7, purified mouse (m) IL-9, rmIL-10, recombinant human (rh) macrophage-colony-stimulating factors (M-CSF), rm granulocyte-macrophage colony-stimulating factors (GM-CSF) rm stem cell factor (SCF), rh interferon-alpha (IFN-alpha), rmIFN-gamma, and mNGF to determine which cytokine would give rise to mast cells in murine BM cultures. From a starting population of 1 x 10(7) cells, 1.55 x 10(7) mast cells developed within 14 days in cultures supplemented by rmIL-3. No mast cells were seen at day 14 when any of the other cytokines were present alone, except for rmSCF, which supported the growth of < 0.01% of mast cells observed in IL-3-dependent BM cultures. When rmIL-4, -5, -7, -10, mIL-9, rhM-CSF, rmGM-CSF, rmSCF, rhIFN-alpha, -gamma, or mNGF were added to BM cultures in the presence of rmIL-3, mast cell growth increased 200% with the addition of rmSCF, and 10% when rmIL-4 or IL-9 was added. However, the addition of rhM-CSF, rmGM-CSF, rmIFN-gamma, and mNGF decreased the number of mast cells. Mast cell number, as determined by metachromatic stains, generally approximated the number of Fc epsilon RI+ cells as assessed by FACS analysis. Among the cytokines, only rmIL-4 and rmSCF were able to support the survival of mast cell progenitors in the absence of obvious mast cell proliferation, similarly to rmIL-3. Only rmSCF alone, or in combination with rmIL-3 or -4, supported the growth of mast cells from mouse peripheral blood mononuclear cells (PBMC) where the number of mast cell precursors was about 90 per 10(6) PBMC. With time, mouse BM cells cultured in rmIL-3 became more responsive to rmSCF. Taken together, these data demonstrate that IL-3 is a major early mast cell growth factor, that mast cells become more dependent on SCF with time, and that the effects of IL-3 and SCF are upregulated (IL-4) or downregulated (M-CSF, GM-CSF, IFN-gamma) by both growth factors and proinflammatory cytokines.
 ...
PMID:Demonstration of differential effects of cytokines on mast cells derived from murine bone marrow and peripheral blood mononuclear cells. 752 67

The mast cell is one of the major effector cells in inflammatory reactions and can be found in most tissues throughout the body. During inflammation, an increase in the number of mast cells can be seen, e.g., in the intraepithelial cell layer after a provoked allergic reaction. Such accumulation probably requires directed migration of mature mast cells or their precursors. To study the migration of human mast cells we used as a model the human mast cell line, HMC-1, and stem cell factor-dependent (also referred to as mast cell growth factor or Kit ligand) cord blood-derived mast cells. The results show that stem cell factor is a potent chemotactic factor for human mast cells in vitro. The chemotactic response to SCF was found to be dose dependent, reaching a maximum at 50 ng/ml. The activity of SCF could be blocked by anti-SCF Abs. We also tested the effect of different intercrines, i.e., IL-8, MIP-1 alpha, MIP-1 beta, RANTES, and MCAF (also referred to as monocyte chemotactic protein 1), on human mast cell migration. Only RANTES was chemotactic for in vitro-developed mast cells. None of the tested intercrines induced migration of HMC-1 cells. For migration, the mast cells were dependent on binding to an extracellular matrix protein. Thus, coating of the filters with fibronectin was required, whereas collagen or laminin did not promote migration. Adhesion of HMC-1 cells to fibronectin could also be shown in an adhesion assay. In addition, expression of receptors for fibronectin could be detected on the surface of the mast cells. These results show that SCF is not only a growth and differentiation factor for human mast cells in vitro but also a potent chemoattractant for such cells.
 ...
PMID:Stem cell factor is a chemotactic factor for human mast cells. 752 4

Autonomous, factor-independent growth and differentiation of malignant cells in preleukemic and leukemic disease states is a well-recognized phenomenon and is often associated with a poor prognosis. Mast cells are distinct hematopoietic cells and express a unique profile of antigens. Growth and differentiation of normal mast cells is dependent on mast cell growth factor (MGF), the ligand of the c-kit protooncogene product. In this study, we screened for mast cell-lineage involvement in 52 patients suffering from myeloid leukemias, myelodysplastic syndromes (MDS), systemic mastocytosis, or other diseases by probing for mast cell-related molecules (c-kit, tryptase, histamine, and MGF) and by analyzing kit ligand/MGF-independent growth of mast cells in long-term suspension culture. Of the 52 patients tested, 2 patients with refractory anemia with excess of blast cells in transformation and 1 patient suffering from chronic myeloid leukemia blast crisis (CML-BC) were diagnosed as mastocytic disease. These patients were characterized by complex chromosomal abnormalities, splenomegaly, high percentages of circulating metachromatic cells (5% to 25%), high levels of cellular tryptase (> 10 ng/10(5) peripheral blood mononuclear cells/mL) and a tryptase/histamine (ng:ng) ratio greater than 1. The metachromatic cells expressed the mast-cell-related surface antigen c-kit, but not basophil-related antigens (CD11b, CDw17). Furthermore, in these 3 patients, spontaneous, MGF-independent growth of mast cells along with spontaneous synthesis of tryptase was demonstrable in long-term culture. No autocrine production, paracrine production, or overproduction of MGF was found. The spontaneous growth of mast cells could neither be abbrogated by addition of monoclonal antibodies (MoAbs) to c-kit nor by MoAbs against MGF (< 5% inhibition), whereas factor (MGF)-dependent differentiation of mast cells in these patients could be abbrogated by MoAbs to c-kit or MoAbs to MGF (> 70% inhibition, P < .001). In addition, serum MGF levels in these patients were within the normal range and MGF could not be detected in cell-free culture supernatants. All 3 patients showed rapid progression of disease and had a survival time of less than 1 year. In conclusion, we describe a unique form of transformation in MDS and CML-BC characterized by mast cell lineage involvement and factor-independent differentiation of mast cells. This form of leukemic transformation has to be delineated from chronic myeloid leukemia with basophilia or basophil crisis, from primary mast cell leukemia, and from monocytic leukemias and myelodysplastic disorders associated with basophilia.
 ...
PMID:Kit ligand/mast cell growth factor-independent differentiation of mast cells in myelodysplasia and chronic myeloid leukemic blast crisis. 752 72

Interaction with stromal cells is known to be crucial for growth and differentiation of hematopoietic cells. To characterize adhesion molecules involved in this interaction, we examined adhesion of a panel of lymphoid, myeloid, and mast cell lines with stromal cells. We found that very late antigen-4 (VLA-4) and vascular cell adhesion molecule 1 (VCAM-1) were major adhesion molecules in lymphoid and myeloid cells, whereas myeloma cells adhered to stromal cells through hyaluronate. We investigated regulation of VLA-4 during differentiation of myeloid cells using a neutrophil precursor cell line, L-G3. Differentiation of neutrophils induced by granulocyte colony-stimulating factor was accompanied with down-regulation of VLA-4. Induced L-G3 cells adhered to stromal cells in proportion to the expression of VLA-4. Mast cells used two mechanisms to adhere to fibroblasts and stromal cells. They adhered to fibronectin through VLA-5 when stimulated with steel factor and also directly to membrane-anchored steel factor through c-kit.
 ...
PMID:Adhesion molecules in hematopoietic cells. 752 78

It has previously been shown that mouse bone marrow-derived mast cells (BMMC) synthesize and secrete endothelin-1 (ET-1) and express ETA-type endothelin receptors (ETA-R). The study presented here was designed to elucidate the influence of different cytokine conditions for cellular differentiation and maturation on the ability of primary mouse BMMC to respond to exogenous ET-1. BMMC were grown for 2 wk in IL-3 alone and then cultured for 2 to 3 wk with kit ligand (KL) and/or IL-3 in the presence or absence of IL-4. ET-1 induced a very rapid (< or = 1 min) and dose-dependent release of histamine and serotonin from BMMC cultured in the presence of both IL-3 and IL-4. The effect of ET-1 was quantitatively comparable with IgE/Ag-induced mediator release and comprised up to 20% and 16% of total cellular histamine and serotonin, respectively. In BMMC grown with KL or KL plus IL-3, a substantial effect of ET-1 on amine release was only observed when IL-4 had been included in the culture medium. These IL-4 effects could not be observed if BMMC grown in IL-3 and/or KL were preincubated for 1 or 24 h with IL-4 before activation with ET-1, suggesting that a differentiation process rather than a functional priming effect had been initiated by IL-4. In BMMC, the histamine and serotonin release induced by ET-1 (10(-6) M) was inhibited by an ETA-R-specific antagonist (cyclic [D-Asp-Pro-D-Val-Leu-D-Trp]) in a dose-dependent manner, with complete inhibition at an antagonist concentration of 10(-8) M. ET-1 stimulated leukotriene C4 biosynthesis up to 4.5-fold in BMMC cultured in the presence of IL-4. No such ET-1 effect was observed in BMMC cultured in media containing IL-3, KL, or a combination of both cytokines. Peritoneal cells (containing 2 to 3% serosal mast cells) obtained from BALB/c mice released 87 +/- 2% of histamine within 1 min after challenge with ET-1. Our results demonstrate that ET-1 can directly act as a histamine and serotonin secretagogue and as a stimulator of leukotriene C4 production in mast cells. IL-4 appears to be critically involved in the differentiation of immature mast cell precursors to an ET-1-reactive phenotype.(ABSTRACT TRUNCATED AT 400 WORDS)
 ...
PMID:IL-4 renders mast cells functionally responsive to endothelin-1. 753 Jul 42

Mechanisms affecting mast cell and melanocyte growth and function are still poorly understood. This report summarizes the current state of knowledge on a recently described growth factor for both these cell types and for primitive haematopoietic stem cells. Stem cell factor (SCF), also named mast cell growth factor or kit-ligand, has only recently been cloned and has been shown to be encoded on human chromosome 12. It may be of specific importance in cutaneous physiology and pathology since it is produced by several cell types in the skin (e.g. fibroblasts, keratinocytes, endothelial cells) and since it affects melanocyte and mast cell growth, survival, secretion and adhesion as well as migration into tissues. Defects in the genes encoding for the SCF receptor (c-kit-protein) have been shown to be responsible for human piebaldism. A pathogenetic role in mastocytosis has recently been proposed, but remains to be proven. SCF receptor expression is decreased on cells of some malignant cell lines compared to their physiological counterparts, making it unlikely that SCF is a key factor in malignant transformation and cellular hyperproliferation. In haematopoiesis, SCF acts primarily in concert with other growth factors, and we show here that alone in serum-free culture it has no effect on mast cell growth. Furthermore, there is evidence that besides SCF, additional mast cell growth factors are secreted by fibroblasts and keratinocytes, suggesting a complex orchestration of several growth factors in the regulation of cutaneous growth and differentiation in which SCF plays only one part.
 ...
PMID:Stem cell factor, a novel cutaneous growth factor for mast cells and melanocytes. 753 33


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>