Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04141 (granulocyte-macrophage colony-stimulating factor)
 6,790 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A new human leukemia cell line with megakaryocytic features, designated UT-7, was established from the bone marrow of a patient with acute megakaryoblastic leukemia. Surface marker analysis revealed that the majority of the cells reacted with monoclonal antibodies against platelet glycoprotein Ib (CD42b), glycoprotein IIb/IIIa (CD41a), MY 7 (CD13), MY 9 (CD33), and glycophorin A antigens. Cytogenetic analysis showed a human male near-tetraploid karyotype with a modal chromosome number of 92-96. Flow cytometry-derived DNA histograms demonstrated that the majority of the cells spontaneously contained 4 N DNA ploidy levels. Ultrastructural study showed that platelet peroxidase activity was weakly positive but myeloperoxidase activity was negative. Ferritin and theta-granule, which have been used as ultrastructural markers for the erythroid lineage, could not be detected. In response to phorbol myristate acetate, platelet factor 4 and beta-thromboglobulin, which were specifically synthesized in the process of megakaryocyte maturation, dramatically increased in UT-7 cells. This was accompanied by an increase in cell size, ploidy level, platelet peroxidase activity, and the surface density of glycoprotein IIb/IIIa antigen. These findings suggest that UT-7 is a new leukemic cell line with megakaryocytic features and with the potential to differentiate into cells with more mature megakaryocytic properties in response to phorbol myristate acetate. This cell line showed strict dependency on interleukin 3 (IL-3), granulocyte-macrophage colony-stimulating factor, or erythropoietin. The maximal effective doses of IL-3, granulocyte-macrophage colony-stimulating factor, and erythropoietin for proliferation in liquid culture were 10 units/ml, 1 ng/ml, and 1 unit/ml, respectively. These concentrations were comparable to the doses that maximally stimulate the clonal growth of normal hemopoietic cells. IL-6 could stimulate the proliferation of UT-7 cells but not maintain the line in long-term culture. UT-7 cells may be a useful model for (a) the analysis of gene regulation of megakaryocytic maturation-associated proteins expressed in the process of megakaryocytic differentiation and (b) the study of signal transduction of hemopoietic factors associated with megakaryocytopoiesis.
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PMID:Establishment and characterization of a human leukemic cell line with megakaryocytic features: dependency on granulocyte-macrophage colony-stimulating factor, interleukin 3, or erythropoietin for growth and survival. 182 23

Developing megakaryocytes are distinguished from progenitor cells by the appearance of platelet proteins such as platelet factor 4 (PF 4). The human erythroleukemic cell line HEL can also be induced to produce PF 4 by incubation in phorbol esters. HEL cells were used here as a model system in which to study the phenomenon of inducible PF 4 production at both the mRNA and protein levels. The cytokines interleukin 1 beta (IL-1 beta), interleukin 3 (IL-3), interleukin 6 (IL-6), granulocyte-macrophage colony-stimulating factor (GM-CSF), erythropoietin (EPO), and transforming growth factor-beta (TGF-beta) were also evaluated for their effects on PF 4 mRNA induction in HEL cells.
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PMID:Platelet factor 4 mRNA expression in human erythroleukemic cells: regulation by phorbol esters and certain cytokines. 186 92

Data concerning megakaryocytopoiesis and its regulation were summarized in this report. Critical analysis of these data indicates that: (i) megakaryocytopoiesis is a complex, multiple-stage cellular and biologic process; (ii) the survival, proliferation and differentiation of progenitor cells into immature megakaryocytes are regulated mainly by interleukin-3, granulocyte-macrophage colony-stimulating factor and an as yet uncharacterized megakaryocyte colony-stimulating factor, and the maturation of immature megakaryocytes to produce platelets is regulated primarily by interleukin-6 and thrombopoietin; (iii) optimal megakaryocyte development needs adequate interactions of several growth factors with target cell population and hematopoietic microenvironment; (iv) megakaryocytopoietic inhibition is controlled essentially by megakaryocyte-platelet products such as transforming growth factor-beta, and platelet factor 4 and its related proteins; interferon-alpha and -gamma also are able to play an inhibitory role; and (v) expansion or decrease of either normal or neoplastic megakaryocyte progenitor cells, change of platelet mass and abnormalities of growth factor levels in hematopoietic tissue might result in an abnormal megakaryocytopoiesis.
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PMID:Megakaryocytopoiesis: characterization and regulation in normal and pathologic states. 195 49

Megakaryocytopoiesis is a complex, highly regulated cellular and biologic process which leads to the production of platelets. The proliferation of megakaryocyte (MK) progenitors is mainly regulated by interleukin-3, granulocyte-macrophage colony-stimulating factor and an as yet uncharacterized MK colony-stimulating factor. The maturation of MKs to produce platelets is essentially regulated by interleukin-6 and thrombopoietin. Optimal megakaryocytopoiesis is controlled by appropriate combinations of positive and negative influence. Megakaryocytopoietic inhibition is controlled by transforming growth factor beta, platelet factor 4 and its related proteins, interferon-alpha and -gamma.
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PMID:Regulation of human megakaryocytopoiesis. 210 71

We report that highly purified human platelet factor 4 (PF4) inhibits human megakaryocytopoiesis in vitro. At greater than or equal to 25 micrograms/ml, PF4 inhibited megakaryocyte colony formation approximately 80% in unstimulated cultures, and approximately 58% in cultures containing recombinant human IL 3 and granulocyte-macrophage colony-stimulating factor. Because PF4 (25 micrograms/ml) had no effect on either myeloid or erythroid colony formation lineage specificity of this effect was suggested. A synthetic COOH-terminal PF4 peptide of 24, but not 13 residues, also inhibited megakaryocyte colony formation, whereas a synthetic 18-residue beta-thromboglobulin (beta-TG) peptide and native beta-TG had no such effect when assayed at similar concentrations. The mechanism of PF4-mediated inhibition was investigated. First, we enumerated total cell number, and examined cell maturation in control colonies (n = 200) and colonies (n = 100) that arose in PF4-containing cultures. Total cells per colony did not differ dramatically in the two groups (6.1 +/- 3.0 vs. 4.2 +/- 1.6, respectively), but the numbers of mature large cells per colony was significantly decreased in the presence of PF4 when compared with controls (1.6 +/- 1.5 vs. 3.9 +/- 2.3; P less than 0.001). Second, by using the human leukemia cell line HEL as a model for primitive megakaryocytic cells, we studied the effect of PF4 on cell doubling time, on the expression of both growth-regulated (H3, p53, c-myc,and c-myb), and non-growth-regulated (beta 2-microglobulin) genes. At high concentrations of native PF4 (50 micrograms/ml), no effect on cell doubling time, or H3 or p53 expression was discerned. In contrast, c-myc and c-myb were both upregulated. These results suggested the PF4 inhibited colony formation by impeding cell maturation, as opposed to cell proliferation, perhaps by inducing expression of c-myc and c-myb. The ability of PF4 to inhibit a normal cell maturation function was then tested. Megakaryocytes were incubated in synthetic PF4, or beta-TG peptides for 18 h and effect on Factor V steady-state mRNA levels was determined in 600 individual cells by in situ hybridization. beta-TG peptide had no effect on FV mRNA levels, whereas a approximately 60% decrease in expression of Factor V mRNA was found in megakaryocytes exposed to greater than or equal 100 ng/ml synthetic COOH-terminal PF4 peptide. Accordingly, PF4 modulates megakaryocyte maturation in vitro, and may function as a negative autocrine regulator of human megakaryocytopoiesis.
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PMID:Inhibition of human megakaryocytopoiesis in vitro by platelet factor 4 (PF4) and a synthetic COOH-terminal PF4 peptide. 252 11

Stimulatory cytokines, including granulocyte-macrophage colony-stimulating factor (GM-CSF) and steel factor (SLF), act in a synergistic manner to stimulate the growth of hematopoietic progenitor cells, an effect also demonstrated for the growth factor-dependent human hematopoietic cell line MO7e. While little is known about the mechanisms responsible for mediating synergistic interactions of cytokines, Raf-1, a component of the MAP kinase signaling pathway, is thought to play a role in the stimulatory response evoked by several cytokines, including SLF and GM-CSF. Interferon-inducible protein-10 (IP-10) and macrophage inflammatory protein-1 alpha (MIP-1 alpha) are members of the chemokine family of suppressive cytokines. Prior exposure of hematopoietic cells to chemokines, including IP-10 and MIP-1 alpha, inhibits the synergistic action of growth factors on stimulating cell proliferation. We report that treatment of MO7e cells with the combination of GM-CSF and SLF directly stimulates statistically significant synergistic increases in the phosphorylation and activation of Raf-1 kinase, and in cellular protein synthesis levels. Pretreatment of MO7e cells with IP-10 or MIP-1 alpha blocked synergistic growth factor action, resulting in statistically significant suppression of cell proliferation, protein synthesis, and Raf-1 phosphorylation and activation. IP-10 and MIP-1 alpha treatment also evoked significant increases in intracellular cAMP levels. Pretreatment of cells with agents which serve to raise intracellular cAMP levels, or with cAMP analogs inhibited the synergistic actions of GM-CSF and SLF in a manner similar to IP-10 and MIP-1 alpha. In addition, treatment of cells with a potent inhibitor of cAMP-dependent protein kinase A blocked the suppressive action of MIP-1 alpha and IP-10 on Raf-1 kinase activity and on MO7e cell proliferation. The ability of IP-10 and MIP-1 alpha to antagonize the synergistic action of GM-CSF and SLF appears to involve inactivation of Raf-1 and the down-regulation of protein synthesis. Our findings suggest that both MIP-1 alpha and IP-10 mediate their suppressive effects in MO7e cells by stimulating increases in cellular cAMP levels and activating protein kinase A, a mechanism we believe to be unique to these chemokines and not one applied to all growth suppressive members of the chemokine superfamily (for example, interleukin 8 and platelet factor 4).
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PMID:Interferon-inducible protein 10 and macrophage inflammatory protein-1 alpha inhibit growth factor stimulation of Raf-1 kinase activity and protein synthesis in a human growth factor-dependent hematopoietic cell line. 1660 26

A number of cytokines have been implicated in the suppression of myeloid stem and progenitor cell proliferation. It has been suggested that some of these act directly on the stem/progenitors themselves, based on the effects of these cells, plated in culture at low seeding densities, on highly enriched populations. These studies, however, do not definitively rule out effects on accessory cells. To more rigorously evaluate direct-acting suppressive effects of cytokines, such cytokines were assessed for their effects on colony formation initiated by single bone marrow (BM) or umbilical cord blood (CB) CD34 cells sorted into single wells in the presence of a combination of growth-stimulating cytokines (erythropoietin [Epo], steel factor [SLF], granulocyte-macrophage colony-stimulating factor [GM-CSF], and interleukin-3 [IL-3]) and in the presence or absence of serum. Under these conditions, it was demonstrated that H-ferritin, transforming growth factor-beta 1 (TGF-beta 1), and members of the chemokine family (macrophage inflammatory protein-1 alpha [MIP-1 alpha], MIP-2 beta, platelet factor 4 [PF4], IL-8, and macrophage chemotactic and activating factor [MCAF]) had direct significant suppressive activities on single stem/progenitor cells from adult human BM in the presence or absence of serum. Single sorted CB cells were much less sensitive to inhibition by these cytokines. The reasons for this differential sensitivity are not known. Of possible relevance to this for cytokines, such as H-ferritin and the chemokines that have actions during S-phase of the cell cycle, CB progenitors were in slower cycle at initiation of culture than were BM progenitors.
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PMID:Comparative effects of suppressive cytokines on isolated single CD34(3+) stem/progenitor cells from human bone marrow and umbilical cord blood plated with and without serum. 769 34

The effect of a low-molecular-weight heparin, faxiparin (Nadroparin), on murine megakaryocytopoiesis in vitro and in vivo was studied in comparison with unfractionated heparin. The addition of fraxiparin at 1-20 IU/ml into plasma clot cultures but not serum-free agar culture significantly enhanced MK colony growth. Furthermore, fraxiparin was found to potentiate the stimulating activity of aplastic anaemia serum (AAS) but not stem cell factor (SCF), interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF) and erythropoietin (Epo), on MK colony growth in vitro, and to neutralize the inhibitory effect of platelet factor 4 (PF4) in vitro and in vivo. Fraxiparin also acted synergistically with heparin cofactor II and antithrombin III to promote megakaryocyte colony formation. Intraperitoneal administration of fraxiparin twice daily for 4 d at 0.1-25 IU/injection increased in mice the level of blood platelet counts and the number of single MKs and CFU-MK in bone marrow. These data demonstrate that fraxiparin is able to positively regulate megakaryocytopoiesis.
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PMID:Fraxiparin, a low-molecular-weight heparin, stimulates megakaryocytopoiesis in vitro and in vivo in mice. 781 73

We have established a novel human megakaryoblastic cell line, designated as MEG-A2, from a patient with megakaryoblastic crisis of Philadelphia (Ph) chromosome positive chronic myelogenous leukemia. MEG-A2 cells showed positive phenotypes for periodic acid Schiff and alpha-naphthylbutyrate esterase reactions, but were negative for myeloperoxidase and naphthol ASD chloroacetate esterase reactions. Flow cytometric analyses of cell surface markers revealed that MEG-A2 cells had a low level of GP IIb/IIIa expression as well as apparent expressions of CD4, CD7, CD13, CD33 and CD34 antigens, but no expression of GP Ib nor glycophorin A. Stimulation with phorbol 12-myristate 13-acetate (PMA) dramatically increased the expression of megakaryocyte-related markers such as HPL-3, J15, Pit-1, Y2/51 and AN51 in MEG-A2 cells. The PMA-stimulation also induced expression of platelet peroxidase (PPO) in MEG-A2 cells on electromicroscopic observation. Proliferative responses to granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3) or erythropoietin were observed, and the expression of GP IIb/IIIa was increased by stimulation with GM-CSF, IL-3, erythropoietin and interleukin-6 (IL-6). Protein S mRNA expression was seen in cultured cells on Northern blot analysis. Expression of platelet factor 4 mRNA was induced in PMA-stimulated cells, and a marked accumulation of protein was observed in the culture medium. In conclusion, a new cell line, MEG-A2, belongs to the relatively immature megakaryocytic lineage and has markedly increased megakaryocytic characteristics with PMA stimulation.
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PMID:Establishment and characterization of an immature human megakaryoblastic cell line, MEG-A2. 786 73

Megakaryocytes and endothelial cells, two important blood and vascular cells, share many similar antigens on their surfaces and in the cytoplasm. It is known that the two types of cells share several developmental regulators: fibroblast growth factors, granulocyte-macrophage colony-stimulating factor, heparin and heparan sulfate, platelet factor 4, transforming growth factor-beta, gamma-interferon, and thrombospondin. Recognition of these common factors and studies with them are broadening the understanding of the pathogenesis of megakaryocytic and angiogenic diseases and encouraging attempts to develop new therapeutic strategies for the future.
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PMID:Are megakaryocytes and endothelial cells sisters? 850 91


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