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 replating capability of human multipotential (colony-forming unit-granulocyte-erythrocyte-macrophage-megakaryocyte [CFU-GEMM]) and erythroid (burst-forming unit-erythroid [BFU-E]) progenitors was assessed in vitro as a potential measure of self-renewal using purified, recombinant (r) human (hu) or murine (mu) mast cell growth factor (MGF), a ligand for the c-kit proto-oncogene receptor. Primary cultures of human umbilical cord blood or adult human bone marrow cells were initiated in methylcellulose with erythropoietin (Epo) alone or in combination with rhu interleukin-3 (IL-3) or MGF. Individual day 14 to 18 CFU-GEMM or BFU-E colonies were removed from primary cultures and reseeded into secondary methylcellulose cultures containing a combination of Epo, MGF, and rhu granulocyte-macrophage colony-stimulating factor (GM-CSF). The data showed a high replating efficiency of cord blood and bone marrow CFU-GEMM in response to Epo + MGF in terms of the percentage of colonies that could be replated and the number of secondary colonies formed per replated primary colony. The average number of hematopoietic colonies and clusters apparent from replated cultures of cord blood or bone marrow CFU-GEMM stimulated by Epo + MGF was greater than with Epo + rhuIL-3 or Epo alone. Replated cord blood CFU-GEMM gave rise to CFU-GEMM, BFU-E, and GM colony-forming units (CFU-GM) in secondary cultures. Replated bone marrow CFU-GEMM gave rise mainly to CFU-GM in secondary cultures. A more limited capacity for replating of cord blood and bone marrow BFU-E was observed. These studies show that CFU-GEMM responding to MGF have an enhanced replating potential, which may be promoted by MGF. These studies also support the concept that MGF acts on more primitive progenitors than IL-3.
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PMID:Mast cell growth factor (c-kit ligand) supports the growth of human multipotential progenitor cells with a high replating potential. 171 90

An evaluation of the effects of a recombinant, soluble form of the c-kit ligand alone and in combination with either granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3 (IL-3) on the regulation of human megakaryocytopoiesis was performed using a serum-depleted clonal assay system and a long-term bone marrow culture system. The effects of the c-kit ligand on the primitive megakaryocyte (MK) progenitor cell, the burst-forming unit-megakaryocyte (BFU-MK), and the more differentiated colony-forming unit-megakaryocyte (CFU-MK) were determined. The c-kit ligand alone had no megakaryocyte colony-stimulating activity (MK-CSA) but was capable of augmenting the MK-CSA of both GM-CSF and IL-3. The range of synergistic interactions of c-kit ligand varied with the class of MK progenitor cell assayed. In the case of the BFU-MK, the c-kit ligand synergistically augmented the numbers of colonies formed in the presence of IL-3, but not GM-CSF, but increased the size of BFU-MK-derived colonies cloned in the presence of both of these cytokines. However, at the level of the CFU-MK, c-kit ligand synergized with both GM-CSF and IL-3 by increasing both colony numbers and size. Although the c-kit ligand alone exhibited limited potential in sustaining long-term megakaryocytopoiesis in vitro, it synergistically augmented the ability of IL-3, but not GM-CSF, to promote long-term megakaryocytopoiesis. These data indicate that multiple cytokines are necessary to optimally stimulate the proliferation of both classes of MK progenitor cells and that the c-kit ligand plays a significant role in this process by amplifying the MK-CSA of both GM-CSF and IL-3.
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PMID:Effect of c-kit ligand on in vitro human megakaryocytopoiesis. 172 39

We tested the ability of recombinant human (rhu) mast cell growth factor (MGF), also known as c-kit ligand, to stimulate the colony formation of human bone marrow cells in semisolid medium alone and in combination with rhu erythropoietin (EPO), rhu Interleukin 3 (IL-3), rhu granulocyte colony stimulating factor (G-CSF) and rhu granulocyte-macrophage colony stimulating factor (GM-CSF). The addition of MGF to cultures containing EPO or EPO + IL-3, GM-CSF and G-CSF, resp., resulted in macroscopic erythroid burst-forming units (BFU-E). Multipotential (colony-forming unit granulocyte, erythroid, monocyte, megakaryocyte [CFU-GEMM]) progenitors were stimulated by MGF in the presence of EPO. Colony-forming unit granulocyte-macrophage (CFU-GM) were activated by MGF only in combination with GM-CSF. The combination of MGF with EPO was used for synergism studies in healthy cynomolgus monkeys. In the chosen concentration MGF alone had no effect on white blood cell (WBC) counts and on platelets, but a slight effect on reticulocytes. EPO by itself increased reticulocyte counts with no effects on WBC or platelets. The combination of both factors resulted in a significant increase of reticulocytes. No other effects were seen. These studies demonstrate the potent synergistic interaction of MGF and other hematopoietic growth factors.
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PMID:Studies on the efficacy of mast cell growth factor (c-kit ligand) in vitro as well as in vivo. 172 1

The effects of recombinant murine macrophage inflammatory protein (MIP)-1 beta and MIP-2 on the suppressive activity of MIP-1 alpha were tested using colony formation by human and murine bone marrow burst-forming unit-erythroid (BFU-E), colony-forming unit-granulocyte erythroid macrophage, megakaryocyte (CFU-GEMM), and colony-forming unit-granulocyte macrophage (CFU-GM) progenitor cells. MIP-1 beta, but not MIP-2, when added with MIP-1 alpha to cells, blocked the suppressive effects of MIP-1 alpha on both human and murine BFU-E, CFU-GEMM, and CFU-GM colony formation. Similar results were observed regardless of the early acting cytokines used: human rGM-CSF plus human rIL-3, and two recently described potent cytokines, a genetically engineered human rGM-CSF/IL-3 fusion protein and MGF, a c-kit ligand. The more potent the stimuli, the greater the suppressive activity noted. Pulse treatment of hu bone marrow cells with MIP-1 alpha at 4 degrees C for 1 h was as effective in inhibiting colony formation as continuous exposure of cells to MIP-1 alpha, and the pulsing effect with MIP-1 alpha could not be overcome by subsequent exposure of cells to MIP-1 beta. Also, pulse exposure of cells to MIP-1 beta blocked the activity of subsequently added MIP-1 alpha. For specificity, the action of a nonrelated myelosuppressive factor H-ferritin, was compared. MIP-1 alpha and H-ferritin were shown to act on similar target populations of early BFU-E, CFU-GEMM, and CFU-GM. MIP-1 beta did not block the suppressive activity of H-ferritin. Also, hemin and an inactive recombinant human H-ferritin mutein counteracted the suppressive effects of the wildtype H-ferritin molecule, but did not block the suppressive effects of MIP-1 alpha. These results show that MIP-1 beta's ability to block the action of MIP-1 alpha is specific. In addition, the results suggest that MIP-1 alpha and MIP-beta can, through rapid action, modulate early myeloid progenitor cell proliferation.
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PMID:Macrophage inflammatory protein (MIP)-1 beta abrogates the capacity of MIP-1 alpha to suppress myeloid progenitor cell growth. 191 79

We examined the effects of interleukin-3 (IL-3) and c-kit ligand (KL) on the survival of differentiated hematopoietic progenitor cells (HPC), the burst-forming unit-erythroid (BFU-E); colony-forming unit-granulocyte, erythroid, monocyte, megakaryocyte (CFU-GEMM); and CFU-granulocyte-monocyte (CFU-GM) and more primitive hematopoietic cells that give rise to these progenitor cells (pre-colony-forming cells [pre-CFC]). CD34+ HLA-DR+ cells, which are highly enriched for committed HPC, and CD34+ HLA-DR- c-kit+ cells, which contain the most primitive assayable hematopoietic cells, including long-term bone marrow culture-initiating cells, high proliferative potential-CFC, the CFU-blast, and the BFU-megakaryocyte, were suspended in serum-free medium in the presence or absence of IL-3 or KL. CD34+ HLA-DR+ cells incubated under serum-free conditions or in the presence of KL for 96 hours lost greater than 90% of assayable unilineage or multilineage HPC, whereas those cells incubated in the presence of IL-3 retained 40% of the number of HPC present at time 0. The effect of IL-3 on HPC survival was most pronounced on the BFU-E and CFU-GEMM present within CD34+ HLA-DR+ cells. Addition of IL-3, but not of KL, to CD34+ HLA-DR+ cells delayed the appearance of morphologic changes and DNA fragmentation patterns associated with cell death occurring by apoptosis. CD34+ HLA-DR-c-kit+ cells were incubated under similar serum-free conditions in the presence or absence of IL-3 or KL, and the frequency of pre-CFC was determined by limiting dilution analysis. The frequency of pre-CFC in cells incubated for 48 hours in the absence of serum was similar to that of cells incubated in the presence of IL-3 and approximately doubled when CD34+ HLA-DR- c-kit+ cells were incubated in the presence of KL. Addition of KL to serum-free suspension cultures of CD34+ HLA-DR- c-kit+ cells delayed the appearance of DNA fragmentation patterns associated with apoptosis to a greater extent than did the addition of IL-3. These studies suggests that IL-3, but not KL, promotes HPC survival, whereas KL plays a greater role than IL-3 in sustaining more primitive HPC, such as pre-CFC. The effects of both cytokines in mediating HPC and primitive hematopoietic cell survival appear to be related, in part, to their ability to suppress apoptosis.
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PMID:Effects of interleukin-3 and c-kit ligand on the survival of various classes of human hematopoietic progenitor cells. 751 Jan 43

The effect of soluble c-kit ligand (stem cell factor, SCF) on human megakaryocytopoiesis of the cells from umbilical cord blood was evaluated in a methylcellulose culture containing human plasma. SCF alone did not stimulate megakaryocyte colony formation by non-phagocytic mononuclear cells (NPMNC), but did so in combination with interleukin (IL)-3, dose-dependently. This stimulatory effect was exhibited more strongly on large megakaryocyte colonies than on small ones. The effects of SCF + IL-3 on the number and size of megakaryocyte colonies exceeded those of IL-6 + IL-3 or of IL-11 + IL-3. The synergistic interaction of SCF with IL-3 was confirmed by using CD34-positive cells. In particular, addition of SCF to the culture with optimal and suboptimal concentrations of IL-3, significantly increased mixed megakaryocyte colony formation as compared with IL-3 alone. Although SCF in combination with IL-6 or IL-11 induced megakaryocyte colonies from NPMNC, these interactions disappeared entirely in the culture using CD34-positive cells. IL-6 or IL-11 significantly increased the size and DNA content of megakaryocytes in the presence of IL-3, while SCF did not affect, or rather decreased, the DNA content. These findings suggest that SCF promotes more strongly the proliferation of primitive rather than mature megakaryocytic progenitors, but does not affect megakaryocytic maturation.
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PMID:Stem cell factor promotes proliferation of human primitive megakaryocytic progenitors, but not megakaryocytic maturation. 751 2

Stem cell factor (SCF) is a cytokine for hematopoietic progenitor cells and plays an important role in megakaryocyte proliferation. The UT-7 cell line was established from a patient with megakaryoblastic leukemia, and its growth and survival are strictly dependent on interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (Epo), or IL-6. In this study, we showed that SCF also supported the growth of UT-7 in the absence of other cytokines and downregulated the cell surface c-kit receptors. Constitutive expression of SCF by introducing SCF expression vector made UT-7 grow factor-independently in liquid medium, but not in semisolid medium. This SCF-expressing factor-independent UT-7 (UT-7scf9) expressed the membrane bound form of SCF on their surface, but did not secrete detectable amounts of soluble SCF. UT-7scf9 formed aggregates as they grew in the absence of cytokines, and this aggregation was inhibited by adding soluble SCF into the medium. UT-7 cultured with SCF and UT-7scf9 cultured without cytokines expressed GM-CSF, and anti-GM-CSF neutralizing antibody partially inhibited their growth. These results suggest that SCF stimulated UT-7 proliferation partially through the autocrine-loop of GM-CSF, and UT-7scf9 expressed SCF mostly as a membrane-bound form, which transduces its growth signal through c-kit receptor as they aggregate by cell-to-cell interaction.
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PMID:Cell-to-cell interaction of cytokine-dependent myeloblastic line constitutively expressing membrane-bound stem cell factor abrogates cytokine dependency partially through granulocyte-macrophage colony-stimulating factor production. 753 35

Nonadherent, low-density T-lymphocyte-depleted (NALT-) CD34 cells from normal human cord blood were assessed in suspension culture for the effects of recombinant cytokines on their proliferation, differentiation, and generation of myeloid progenitor cells. In this cell population, 82% of cells expressed c-kit protein as assessed by in situ hybridization, and their cloning efficiency was 85% when cells were plated at low cell numbers with combinations of growth factors. CD34 cells were sorted as 1, 5, or 10 cell(s) per well and also at 5000 cells per dish to initiate stromal-free suspension cultures in the presence of steel factor (SLF), interleukin (IL)-1 alpha, and IL-3. Forty-eight percent of the wells started with a single CD34 cell were positive for growth after 14 days, and the wells contained greater than 5 x 10(3) cells by 21-28 days. Progenitors were assayed weekly with cultures initiated with 1 or 5000 cells. While the fold expansion of nucleated cells was greater in cultures initiated with one cell per well (> 5000 compared to 791-fold expansion for 5000 cells), the fold expansion of progenitors was greater than 5000 cells were used to initiate cultures. Under optimal conditions, there was, respectively, a 160-, 164-, and 57-fold output of high proliferative potential colony-forming cells, granulocyte-macrophage colony-forming units, and erythroid burst-forming units/granulocyte erythroid macrophage megakaryocyte colony-forming units within 1-3 weeks for cultures initiated with 5000 CD34 cells compared with respective fold increases of 29, 16, and 1, for single-initiated cultures. These results demonstrate the expansion capacity of single CD34 cord blood cells and demonstrate that factors in addition to SLF, IL-1 alpha, and IL-3 are necessary for optimal expansion of progenitors from single isolated CD34 cells.
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PMID:Extensive proliferative capacity of single isolated CD34 human cord blood cells in suspension culture. 753 51

We have evaluated the effects of the flt3 receptor ligand (FL) on hematopoietic progenitors/stem cells (HPCs/HSCs) stringently purified from adult peripheral blood and grown in different culture systems. In these experiments HPCs/HSCs were treated with FL +/- kit ligand (KL) +/- monocyte colony-stimulatory factor (M-CSF). In clonogenetic HPC culture supplemented with interleukin-3 (IL-3)/granulomonocyte-CSF (GM-CSF)/erythropoietin (Epo), FL potentiates colony-forming unit (CFU)-GM proliferation in terms of colony number and size, but exerts little effect on burst-forming units-erythroid (BFU-E) and CFU-granulocyte erythroid megakaryocyte macrophage (CFU-GEMM) growth, whereas KL enhances the proliferation of all HPC types; combined FL+KL +/- M-CSF treatment causes a striking shift of CFU-GM colonies from granulocytic to monocytic differentiation. In liquid suspension HPC culture, FL alone induces differentiation along the monocytic and to a minor extent the basophilic lineages, whereas M-CSF alone stimulates prevalent monocytic differentiation but little cell proliferation: combined M-CSF+FL treatment causes both proliferation and almost exclusive monocytic differentiation (97% monocytes in fetal calf serum-rich (FCS+) culture conditions, mean value). At primitive HPC level, FL potentiates the clonogenetic capacity of colony-forming units-blast (CFU-B) and high proliferative potential colony-forming cells (HPP-CFC) in primary and secondary culture; KL exerts a similar action, and additive effects are induced by FL combined with KL. More important, addition of FL alone causes a significant amplification of the number of long-term culture-initiating cells (LTC-ICs), ie, putative repopulating HSCs, whereas this effect is not induced by KL. The FL effects correlate with flt3 mRNA expression in HPCs differentiating throught the erythroid or GM pathway in liquid suspension culture: (1) flt3 mRNA is expressed in freshly purified, resting HPCs; after growth factor stimulus the message (2) is abruptly down-modulated in HPC erythroid differentiation, but (3) is sustainedly expressed through HPC GM differentiation and abolished in GM precursor maturation. This pattern contrasts with the gradual downmodulation of c-kit through both erythroid and GM HPC differentiation. The results indicate that FL exerts a stimulatory action on primitive HPCs, including a unique expanding effect on putative stem cells, whereas its distal proliferative/differentiative action is largely restricted to CFU-GM and monocytic precursors. The latter effect is potentiated by KL and M-CSF, thus suggesting that the structural similarities of FL, KL, M-CSF, and their tyrosine kinase receptors may mediate positive interactions of these growth factors son monocytic differentiation.
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PMID:Multi-level effects of flt3 ligand on human hematopoiesis: expansion of putative stem cells and proliferation of granulomonocytic progenitors/monocytic precursors. 754 38

Cellular and molecular analysis of megakaryocytopoiesis has been hampered thus far by the lack of pure and abundant megakaryocyte (MK) cell populations. In this study, hematopoietic progenitor cells (HPCs), stringently purified from peripheral blood, were induced to megakaryocytic differentiation/maturation in serum-free liquid suspension culture treated with a growth factor cocktail (interleukin-3 [IL-3], c-kit ligand, and IL-6) and/or recombinant mpl ligand (mpIL). In particular, (1) the growth factor cocktail induced the growth of a 40% MK population, ie, 4 x 10(4) cells at day 0 generated 2 x 10(5) MK at terminal maturation; (2) further addition of mpIL increased the MK purity level to 80% with a final yield of 4 x 10(5) MKs; (3) treatment with mpIL alone resulted in a 97% to 99% MK population, with a mild increase of cell number (to 1.5 x 10(5) cells). In mpIL-supplemented culture, morphological evaluation indicated the presence of putative mononuclear MK precursors and then of mature polynucleated platelet-forming MKs, peaking at days 5 and 12, respectively. Membrane phenotype analysis showed a gradual decrease of CD34+ HPCs, coupled with an inverse increase of MK-specific antigens (eg, CD61/62/42b) starting before mature MK detection by morphology analysis. In situ hybridization showed the expression of MK-specific von Willebrand gene in both MK precursors and mature MKs. Furthermore, MKs synthesize and secrete low but significant amounts of both IL-6 and granulocyte-macrophage colony-stimulating factor. Comparative culture studies were performed on purified bone marrow CD34+/38hi or CD34+/38lo cells stimulated by mpIL alone. Both populations generated a highly enriched MK progeny (62% and 93% MKs at day 12 of culture, respectively) but showed either little or no proliferation. In conclusion, the purified peripheral blood HPC differentiation culture system allows for growth of a relatively large number of highly purified or "pure" megakaryocytic precursors and then mature MKs, thus providing an in vitro experimental tool to dissect the cellular and molecular basis of megakaryocytopoiesis.
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PMID:Unilineage megakaryocytic proliferation and differentiation of purified hematopoietic progenitors in serum-free liquid culture. 757 39


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