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)

The cDNA for canine stem cell factor (cSCF, c-kit ligand) was cloned and expressed in Escherichia coli. The recombinant protein (rcSCF), 165 amino acids in length, is very similar structurally to the soluble form of previously cloned and sequenced rodent and human SCFs. The biological effects of rcSCF were studied in a day-10 granulocyte-macrophage colony-forming unit (CFU-GM) clonogenic assay and in long-term liquid bone marrow culture of non-adherent hematopoietic cells in the absence of a stromal underlayer. Synergism in the stimulation of growth of CFU-GM was demonstrated between rcSCF and both recombinant human (rh) granulocyte-macrophage colony-stimulating factor (GM-CSF) and naturally occurring colony-stimulating activity present in the serum of a neutropenic dog. Alone, rcSCF was nonstimulatory for committed marrow precursors in methylcellulose cultures and had minimal effect on hematopoietic progenitor cell survival in stromaless, liquid cultures. When rcSCF was combined with phytohemagglutinin-stimulated canine lymphocyte-conditioned medium (PHA-LCM) or rh interleukin 6 (IL-6), with or without rhGM-CSF, CFU-GM survived for up to 5 weeks. The combination of rcSCF and rhGM-CSF, without rhIL-6, led to an early increase in CFU-GM in liquid cultures that declined more rapidly than in flasks that included rhIL-6. Survival of progenitor cells was negligible beyond 1 week in flasks with growth factor combinations lacking rcSCF. Sustained production of nonadherent cells in long-term cultures also was dependent on rcSCF in combination with canine PHA-LCM or recombinant human growth factors. It appears that rcSCF, like that from rodent and primate species, has the ability to influence the survival and proliferation of CFU-GM, and perhaps earlier progenitor cells, in hematopoietic tissues. In a long-term liquid culture system in which growth factor production by stromal cells is limited, rcSCF possesses a unique ability to maintain the viability of progenitor cells for up to 5 weeks.
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PMID:Canine stem cell factor (c-kit ligand) supports the survival of hematopoietic progenitors in long-term canine marrow culture. 128 86

Stem cell factor (SCF) stimulates the growth of burst-forming unit-erythroid (BFU-E) and colony-forming unit granulocyte-macrophage (CFU-GM) by binding to a specific cell surface receptor. The receptor for SCF is encoded by the protooncogene c-kit. After immunizing mice with the human erythroleukemia cell line OCIM1, we obtained a monoclonal antibody (MoAb) that recognizes the human c-kit receptor. This MoAb, designated SR-1, blocks binding of 125I-human SCF to the c-kit receptor, and neutralizes the biologic effects of SCF in hematopoietic colony assays. With few exceptions, c-kit expression was identified on all hematopoietic and lymphoid cell lines tested by indirect immunofluorescent analysis using SR-1 and by binding studies with 125I-SCF. SR-1 recognizes a small fraction of normal bone marrow mononuclear cells, and these cells have the morphologic appearance of blasts. Colony assays show that BFU-E and CFU-GM display the c-kit receptor. SR-1 does not cross-react with murine c-kit protein, indicating that the binding epitopes of the human and murine c-kit receptors are antigenically distinct. This MoAb may be useful to characterize the spectrum of cells that display the c-kit receptor and to further define the role of SCF in hematopoiesis.
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PMID:Isolation and characterization of a monoclonal antibody that recognizes the human c-kit receptor. 137 Mar 84

A mouse antihuman monoclonal IgG2a antibody, termed stem cell receptor-1 (SR-1), specific for a determinant of the c-kit ligand receptor (KR), was used as an immunologic probe to analyze KR expression by human bone marrow hematopoietic progenitor cells. Monoclonal antibodies to CD34 and HLA-DR were used in a multicolor staining protocol in conjunction with SR-1 to further define the phenotypes of various classes of hematopoietic progenitor cells. Expression of KR (SR-1+) on hematopoietic progenitor cells identified subpopulations of cells expressing CD34 (CD34+). While one-half of the CD34- and HLA-DR-expressing cells (CD34+ HLA-DR+) expressed the KR (SR-1+), one-third of the CD34+ cells that lacked HLA-DR expression (CD34+ HLA-DR-) were SR-1+. The CD34+ HLA-DR+ SR-1+ cell population contained the vast majority of the more differentiated progenitor cells, including the colony-forming unit (CFU) granulocyte-macrophage; burst-forming unit-erythrocyte; CFU-granulocyte, erythrocyte, macrophage, megakaryocyte; and the CFU-megakaryocyte. The overall progenitor cell cloning efficiency of this subpopulation was greater than 31%. By contrast, the CD34+ HLA-DR- SR-1+ cell population contained fewer of these more differentiated progenitor cells but exclusively contained the more primitive progenitor cells, the BFU-megakaryocyte, high proliferative potential-colony-forming cell, and long-term bone marrow culture-initiating cell. The overall progenitor cell cloning efficiency of this subpopulation was greater than 7%. Both the CD34+ HLA-DR- and CD34+ HLA-DR+ cell subpopulations lacking KR expression contained few assayable hematopoietic progenitor cells. Long-term bone marrow cultures initiated with CD34+ HLA-DR- SR-1+ but not CD34+ HLA-DR- SR-1- cells, which were repeatedly supplemented with c-kit ligand (KL) and interleukin-3, generated assayable progenitor cells of at least 2 lineages for 10 weeks. These experiments demonstrate the expression of the KR throughout the hierarchy of human hematopoietic progenitor cell development. We conclude from our data that the KL and KR play a pivotal role in cytokine regulation of both the primitive and more differentiated human hematopoietic progenitor cells.
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PMID:Further phenotypic characterization and isolation of human hematopoietic progenitor cells using a monoclonal antibody to the c-kit receptor. 137 42

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 aim of this study was to evaluate the effect of stem cell factor (SCF) on the in vitro growth of bone marrow hematopoietic progenitors from patients with acquired severe aplastic anemia (AA) or Fanconi's anemia (FA). For this purpose, we studied 11 patients with acquired AA (5 at diagnosis, 6 after ALG treatment), 12 patients with FA, and nine normal controls. Bone marrow cells were plated in vitro for colony-forming unit granulocyte-macrophage (CFU-GM) (in the presence of granulocyte-macrophage colony-stimulating factor [GM-CSF]), and for burst-forming unit-erythroid (BFU-E) and CFU-granulocyte, erythroid, monocyte, megakaryocyte (CFU-GEMM) colonies (in the presence of erythropoietin and interleukin-3 [IL-3]), with or without 20 ng/mL of SCF. In normal controls, SCF enhanced the growth of CFU-GM colonies from 103 to 263 (median), of BFU-E from 168 to 352, and of GEMM colonies from 6 to 38/10(5) cells plated. In patients with acquired AA, SCF induced a significant enhancement of BFU-E growth (8 to 29; P = .01) and allowed the formation of GEMM colonies that were not scored in baseline culture conditions (0 to 8; P = .01). CFU-GM growth was enhanced (4 to 20), but not significantly (P = .3). This was true both for patients at diagnosis and after antilymphocyte globulin treatment. By contrast, 10 of 12 FA patients grew no CFU-GM, BFU-E, or CFU-GEMM colonies, with or without SCF. In two FA patients (one transfusion-dependent and one transfusion-independent), an enhancement of CFU-GM and/or BFU-E was observed. The lack of response of hematopoietic progenitor cells from FA patients to GM-CSF+SCF or IL-3+SCF was not dependent on a defective expression of cytokine receptor messenger RNAs. Northern blot analysis showed in marrow cells from acquired AA and FA patients the presence of normal transcripts for alpha- and beta-chains of GM-CSF/IL-3 receptor and for c-kit protein. In conclusion, SCF promotes the in vitro growth of hematopoietic progenitors in patients with acquired AA, but not in patients with FA, pointing out the intrinsic nature of the defect in the latter disorder.
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PMID:Effect of stem cell factor on colony growth from acquired and constitutional (Fanconi) aplastic anemia. 137 17

The high levels of hematopoietic growth factors required for in vitro and in vivo activity raise questions as to their role in normal hematopoietic maintenance. We hypothesize that the use of combinations of cytokines to stimulate hematopoietic progenitors might allow individual factors to exert their influence at lower, more physiologically relevant concentrations. Growth factor combinations were assessed by their ability to stimulate both total colonies and high proliferative potential colony-forming cells (HPP-CFC), an early murine hematopoietic progenitor, in double-layer agar cultures. Very-low-level combinations of colony-stimulating factor (CSF)-1, granulocyte CSF (G-CSF), granulocyte-macrophage CSF (GM-CSF), interleukin (IL)-1 alpha, and IL-3 had little or no clonogenic capacity. Plateau levels of rr stem cell factor (rrSCF), a c-kit ligand, used alone also had negligible clonogenic capacity, but when combined with the low-level combination of the other five factors produced total colony and HPP-CFC growth approaching that produced by all factors at plateau levels. Delayed addition experiments suggest that this effect may represent sequential activity of SCF and the other factors. We propose a model of the normal hematopoietic microenvironment in which SCF at locally high concentration on the stromal cell surface "anchors" the hematopoietic stem cell's response to multiple other cytokines at physiologically relevant levels.
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PMID:Stem cell factor induction of in vitro murine hematopoietic colony formation by "subliminal" cytokine combinations: the role of "anchor factors". 137 85

The effects of recombinant rat stem cell factor (SCF/c-kit ligand) on murine megakaryocytopoiesis were studied using partially purified bone marrow cells derived from normal and 5-fluorouracil (5-FU)-treated mice in a serum-free culture system. SCF alone did not support the formation of megakaryocyte (M) and granulocyte-macrophage-megakaryocyte (GMM) colonies. However, the addition of SCF to cultures containing interleukin-3 (IL-3) resulted in a significant increase in the number of M and GMM colonies formed by bone marrow cells from normal mice, whereas IL-6 augmented only M colony growth. The stimulatory effect of SCF was approximately three to four times as high as that of IL-6 on the primitive progenitors capable of megakaryocytic-lineage expression derived from 5-FU-treated mice. In addition, SCF, but not IL-6, significantly increased the number of constituent cells in the individual M colonies supported by IL-3. On the other hand, SCF did not exert any effect on the size and DNA content of megakaryocytes in IL-3-dependent M and GMM colonies, whereas IL-6 enhanced the maturation of megakaryocytes. These results suggest that SCF stimulates the proliferative process in megakaryocytic progenitors and that the main activity of IL-6 is the promotion of megakaryocyte maturation.
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PMID:Stem cell factor enhances proliferation, but not maturation, of murine megakaryocytic progenitors in serum-free culture. 138 2

The effects of the c-kit ligand (stem cell factor [SCF]) on the development of a highly enriched population of granulocyte-macrophage colony-forming cells (GM-CFC) were assessed. In soft agar assays, both in serum-containing and in serum-deprived cultures, SCF promoted the formation of colonies that contained predominantly granulocytic cells with some blast cells also present. The size of these colonies was far smaller than observed in the presence of interleukin-3 (IL-3). In serum-deprived conditions, no colonies were formed in the presence of macrophage colony-stimulating factor (M-CSF), but when M-CSF was combined with SCF, a marked change was noted in that large colonies were produced containing predominantly macrophages. When GM-CFC were cultured in the presence of IL-3 and SCF, colonies were formed that contained blast cells, granulocytes, and macrophages. A synergistic interaction was also seen using a combination of G-CSF plus SCF in either serum-containing or serum-deprived cultures. The addition of SCF to colony-forming assays markedly reduced the concentration of IL-3 or G-CSF required for optimal levels of colony formation. Furthermore, SCF was capable of promoting the survival of GM-CFC for several days, after which large colonies containing mature cells were formed upon the addition of a secondary growth factor such as G-CSF or IL-3. Thus, SCF can directly act on highly enriched committed progenitor cells in serum-deprived conditions to promote survival, proliferation, and development.
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PMID:Stem cell factor directly stimulates the development of enriched granulocyte-macrophage colony-forming cells and promotes the effects of other colony-stimulating factors. 138 98

Purified natural and recombinant murine mast cell growth factor (MGF, a c-kit ligand) were evaluated alone and in combination with other cytokines for effects in vitro on colony formation by multipotential (CFU-GEMM), erythroid (BFU-E) and granulocyte-macrophage (CFU-GM) progenitor cells from BDF1 mouse bone marrow. Both preparations stimulated Epo-dependent CFU-GEMM and enhanced Epo-dependent BFU-E colony numbers and size. MGF had some stimulating activity for CFU-GM. When used in combination with plateau concentrations of pokeweed mitogen mouse spleen cell conditioned medium or granulocyte-macrophage colony stimulating factor (CSF), MGF enhanced in greater than additive fashion colony formation by CFU-GM. MGF also enhanced the size of colonies formed, an enhancement greatest for colonies containing granulocytes and macrophages. MGF did not enhance Macrophage-CSF stimulated colony numbers or size. MGF seems to be an early acting cytokine with preferential effects on the growth of more immature hematopoietic progenitor cells.
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PMID:Influence of murine mast cell growth factor (c-kit ligand) on colony formation by mouse marrow hematopoietic progenitor cells. 170 68

Purified natural (n) and recombinant (r) murine (mu) mast cell growth factor (MGF, a c-kit ligand) were evaluated alone and in combination with r human (hu) erythropoietin (Epo), rhu granulocyte-macrophage colony-stimulating factor (rhuGM-CSF), rhuG-CSF, and/or rhuM-CSF for effects in vitro on colony formation by multipotential (colony-forming unit-granulocyte, erythroid, monocyte, megakaryocyte [CFU-GEMM]), erythroid (burst-forming unit erythroid [BFU-E]) and granulocyte-macrophage (CFU-GM) progenitor cells from normal human bone marrow. MGF was a potent enhancing cytokine for Epo-dependent CFU-GEMM and BFU-E colony formation, stimulating more colonies and of a larger size than either rhu interleukin-3 (rhuIL-3) or rhuGM-CSF. MGF, especially at lower concentrations, also acted with rhuIL-3 or rhuGM-CSF to enhance Epo-dependent CFU-GEMM and BFU-E colony formation. MGF had little stimulating activity for CFU-GM colonies by itself, but in combination with suboptimal to optimal amounts of rhuGM-CSF enhanced the numbers and the size of CFU-GM colonies in an additive to greater than additive manner. While we did not detect an effect of MGF on CFU-G colony numbers stimulated by maximal concentrations of rhuG-CSF, MGF did enhance the size of CFU-G-derived colonies. MGF did not enhance the activity of rhuM-CSF. In a comparative assay, maximal concentrations of rmu and rhuMGF were equally effective in the enhancement of human bone marrow colony formation, but rhuMGF, in contrast to rmuMGF, did not at the concentrations tested enhance colony formation by mouse bone marrow cells. MGF effects on BFU-E, CFU-GM, and CFU-GEMM may be direct acting ones as MGF-enhanced colony formation by these cells in highly enriched progenitor cell populations of CD34 HLA-DR+ and CD34 HLA-DR+CD33- sorted cells in which greater than or equal to 1 of 2 cells was a BFU-E plus CFU-GM plus CFU-GEMM. MGF appears to be an early acting cytokine that preferentially stimulates the growth of immature hematopoietic progenitor cells.
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PMID:Effect of murine mast cell growth factor (c-kit proto-oncogene ligand) on colony formation by human marrow hematopoietic progenitor cells. 170 71


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