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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)

Gamma irradiation of plateau-phase clonal bone marrow stromal cell lines produces factor-independent growth of cocultivated clonal interleukin-3/granulocyte-macrophage colony-stimulating factor-dependent hematopoietic progenitor cell lines. The process is associated with three biologic changes including: (i) adherence of hematopoietic cells to stromal cells forming 'cobblestone islands'; (ii) an intermediate stage [during which the cells show proliferation in suspension in the presence in leukemogenic stromal factor (LSF), a factor similar to macrophage colony-stimulating factor (M-CSF) released by irradiated stromal cells, and transient hematopoietic cell surface expression of MAC-1, and c-fms (M-CSF receptor)]; and (iii) a third stage of factor-independence. A monoclonal antibody to M-CSF receptor inhibited proliferation of intermediate stage but not all factor-independent cell subclones. In the present studies, a subclonal factor-independent malignant subline of FDC-P1JL26 derived by cocultivation with gamma-irradiated stromal cells as well as the parent clone and intermediate stage cells were shown to express significant levels of M-CSF polyA+ mRNA and M-CSF of at least two sizes (23 and 15 kDa) as detected by 35S-methionine labelling and immunoprecipitation with polyclonal anti-M-CSF antiserum. There was no significant difference in intracellular M-CSF protein size between cells at each of the three stages of biologic change. This M-CSF was not detected on the cell surface by fluorescence-activated cell sorting (FACS). In contrast, c-fms expression at the cell surface was detected by FACS analysis and c-fms polyA+ mRNA was only detected during the intermediate stage of induction of factor-independence. FDC-P1JL26 parent cells, the subclone stimulated by LSF, and the factor-independent subclone, showed little or no detectable autophosphorylation of the c-fms receptor at tyrosine. There was no detectable rearrangement of the M-CSF or c-fms genes by Southern analysis between clonal lines during the three stages. While we cannot rule out an autocrine mechanism or mutated c-fms receptor mechanism, the data also suggest that evolution of hemopoietic cell factor-independence during cocultivation with irradiated stromal cells may involve a mechanism distal to the c-fms receptor/M-CSF interaction.
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PMID:Expression of M-CSF and its receptor (C-FMS) during factor-independent cell line evolution from hematopoietic progenitor cells cocultivated with gamma irradiated marrow stromal cell lines. 138 39

Platelet-activating factor (PAF; 1-alkyl-2-acetyl-sn-glycero-3- phosphocholine) is a mediator involved in the pathogenesis of inflammatory diseases associated with tissue eosinophil infiltration. Previous studies utilizing bioassay or assaying enzymes associated with PAF biosynthesis have suggested that human eosinophils produce PAF. The present study has extended these initial studies by identifying and quantifying the different PAF molecular species and analogues synthesized by human eosinophils in response to A23187 and f-Met-Leu-Phe (FMLP). Gas chromatography-mass spectrometric analysis indicated that A23187-stimulated eosinophils produce at least three molecular species of PAF. The predominant species is 1-hexadecyl-2-acetyl-GPC (16:0) followed by 1-octadecyl-2-acetyl-GPC (18:0) and 1-octadecyl-2-acetyl-GPC (18:1). Eosinophils stimulated with FMLP produce approximately 100-fold smaller quantities of PAF relative to those produced in response to A23187 and only the 16:0 molecular species could be measured. A small percentage (comprising between 2 and 5%) of the 2-acetylated phospholipids produced by eosinophils was the 1-acyl analogue of PAF. Long-term (72 hr) incubation with granulocyte-macrophage colony-stimulating factor (GM-CSF) resulted in a three- to fourfold increase in PAF synthesis from eosinophils stimulated with FMLP, without changes in the profile of PAF molecular species or in the percentage of the 1-acyl analogue of PAF. These data indicate that human eosinophils can produce various molecular species of PAF and that this process can be quantitatively enhanced by GM-CSF.
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PMID:Characterization of platelet-activating factor synthesized by normal and granulocyte-macrophage colony-stimulating factor-primed human eosinophils. 149 22

1. The addition of 2 x 10(8) human platelets to 8 x 10(6) polymorphonuclear leucocytes (PMNL) incubated in presence of 2.5 u ml-1 thrombin and 0.1 microM N-formyl-Met-Leu-Phe (FMLP) (or C5a or PAF) led to enhancement of leukotriene B4 (LTB4) synthesis by the PMNL (measured by h.p.l.c. as 20-hydroxy- and 20-carboxy-LTB4) from 4 +/- 1 pmol (in absence of platelets) to 26 +/- 4 pmol (mean +/- s.e.mean, n = 9). Platelets and thrombin were both essential for the enhancement of LTB4 synthesis. 2. Platelets also caused enhancement of LTB4 synthesis from (30 +/- 12 to 134 +/- 25 pmol, n = 6) when PMNL pretreated with granulocyte-macrophage colony-stimulating factor were used in similar experiments. 3. Enhancement of LTB4 synthesis was also observed (from 5 +/- 1.5 to 26.5 +/- 5 pmol, n = 9) when the supernatants of thrombin-activated platelet suspensions were added to FMLP-stimulated PMNL. 4. Supernatants of platelet suspensions activated by thrombin in presence of cyclo-oxygenase and 12-lipoxygenase inhibitors led to greater enhancement (from 5 +/- 3 to 153.5 +/- 27.5 pmol, n = 3) of LTB4 synthesis by FMLP-stimulated PMNL, suggesting that arachidonic acid itself, rather than its metabolites was responsible for the effects of platelets. 5. Addition of arachidonic acid to FMLP-stimulated PMNL at a concentration comparable to that measured in thrombin-activated platelet supernatants (0.2 +/- 0.025 microM, n = 6) mimicked the effect of platelets or platelet supernatants on LTB4 synthesis in FMLP-activated PMNL. 6. The present data indicate that under conditions of cell activation by physiological agonists, platelets can significantly increase the formation of the proinflammatory compound LTB4 in PMNL by providing arachidonic acid. These data lend support to the concept that platelet-PMNL interactions could modulate the inflammatory process.
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PMID:Thrombin-activated platelets promote leukotriene B4 synthesis in polymorphonuclear leucocytes stimulated by physiological agonists. 165 46

Human granulocyte colony-stimulating factor (G-CSF) is a regulatory glycoprotein that stimulates the production of neutrophilic granulocytes from committed hematopoietic progenitor cells both in vitro and in vivo. In this report, we show that biosynthetic (recombinant) human G-CSF enhances colony formation by normal human bone marrow and the human myeloid leukemic cell lines, HL-60 and KG-1, as well as nonhematopoietic small cell lung cancer lines, H128 and H69. G-CSF also modulates multiple differentiated functions of human neutrophils, including enhanced oxidative metabolism in response to f-Met-Leu-Phe (f-MLP), increased antibody-dependent cell-mediated cytotoxicity (ADCC), and augmented arachidonic acid release in response to ionophore and chemotactic agents. These effects are all maximal at a concentration of 100 to 500 pmol/L. Using 125I-labeled recombinant human G-CSF, high affinity binding sites were identified on human neutrophils, the myeloid leukemia cell lines KG-1 and HL-60, and the small cell carcinoma cell lines, H128 and H69. G-CSF receptor numbers ranged between 138 and 285 sites per cell with a kd of 77 to 140 pmol/L, consistent with the concentrations of G-CSF that elicit biologic responses in vitro. Decreased specific binding of 125l-G-CSF by human neutrophils was consistently observed in the presence of excess unlabeled human granulocyte-macrophage colony-stimulating factor (GM-CSF), suggesting competition or down modulation by GM-CSF of the G-CSF receptor.
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PMID:Human granulocyte colony-stimulating factor: biologic activities and receptor characterization on hematopoietic cells and small cell lung cancer cell lines. 168 90

Recombinant interleukin 4 (IL4) down-regulates the expression of CD14 on normal human monocytes, as assessed by flow cytometry, binding assays with radiolabeled anti-CD14 monoclonal antibody (mAb), and immunoprecipitation of 125I-labeled monocytes with anti-CD14 mAb. In parallel, CD23 expression on monocytes was strongly increased by IL4 stimulation, as assessed by both flow cytometry and immunoprecipitation. Down-regulation of surface CD14 was first detectable after 24-36 h of incubation with rIL4, and was almost complete after 4 days of culture. None of the other recombinant lymphokines tested (IL1, IL2, IL3, IL5, IL6, interferon-gamma, tumor necrosis factor alpha and beta, granulocyte-macrophage colony-stimulating factor) decreased CD14 expression. Metabolic labeling studies with [35S]methionine showed that both the membrane-associated and the soluble form of CD14 are decreased by IL4 stimulation. Northern blot analysis showed that incubation of monocytes with IL4 induced a marked decrease in CD14 mRNA. Nuclear run-off assays revealed that the IL4-dependent down-regulation of CD14 resulted from decreased transcription. Thus, IL4 exerts specific and opposite effects on the expression of monocytic antigens.
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PMID:Interleukin 4 down-regulates the expression of CD14 in normal human monocytes. 170 91

Erythrocyte development in mammals depends in part upon the interaction of the glycopeptide hormone erythropoietin (EPO) with cell surface receptors on committed erythroid progenitor cells. Both this factor and an EPO receptor polypeptide previously have been cloned, yet little is presently understood concerning molecular mechanisms of receptor activation and signal transduction. To identify cytosolic receptor domains necessary for signaling, we have compared the activities of a series of deletionally mutated EPO receptor constructs by their expression in interleukin 3-dependent, myeloid FDC-P1 cells. EPO-induced growth was transduced efficiently in these cells by the full-length receptor (507 amino acids), and no measurable loss in activity resulted from the deletion of up to 111 carboxyl-terminal residues. In contrast, the deletion of 44 additional residues led to a dramatic loss (86.3% +/- 7.8%; mean +/- SD) in the ability of this receptor to mediate EPO-induced growth, thus indicating that residues between Gly-352 and Met-396 constitute a functionally critical cytosolic subdomain. Interestingly, the expression of full-length EPO receptors in FDC-P1 cells also led to a selective inhibition of normal proliferative responsiveness to the alternative hematopoietic factor granulocyte-macrophage colony-stimulating factor. Moreover, this inhibition was progressively reversed in forms of the EPO receptor in which distal cytosolic residues were sequentially deleted. These results suggest that EPO receptors normally may trans-modulate components in the pathway of granulocyte-macrophage colony-stimulating factor-induced proliferation and that this down-modulation, as exerted by intact EPO receptors, may play a role in promoting erythroid commitment during myeloid blood cell development.
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PMID:Localized cytosolic domains of the erythropoietin receptor regulate growth signaling and down-modulate responsiveness to granulocyte-macrophage colony-stimulating factor. 171 Dec 11

Tumor necrosis factor (TNF) acts as a potent enhancer of granulocyte-macrophage colony-stimulating factor (GM-CSF)- and interleukin-3 (IL-3)-induced human acute myeloid leukemia (AML) growth in vitro. We have analyzed the effects of TNF alpha on the expression of GM-CSF and IL-3 receptors on AML cells. Incubation of blasts from seven patients with AML in serum-free medium with TNF (10(3) U/mL) and subsequent binding studies using 125I-GM-CSF and 125I-IL-3 show that TNF increases the specific binding of GM-CSF (30% to 280%) and IL-3 (40% to 600%) in all cases. From Scatchard plot analysis it appears that TNF upregulates (1) low-affinity GM-CSF binding sites, (2) common high-affinity IL-3/GM-CSF binding sites, and (3) unique (non-GM-CSF binding) IL-3 binding sites. The effect of TNF is dose dependent and is half maximal at a concentration of 100 U/mL, and becomes evident at 18 hours of incubation with TNF at 37 degrees C, but not at 0 degree C. The GM-CSF dose-response curve of AML-colony-forming units plateaus at a higher level in the presence of TNF, which indicates that additional numbers of cells become responsive to GM-CSF. Incubation of AML blasts with the phorbol ester 12-0-tetradecanoylphorbol-13-acetate or formyl-Met-Leu-Phe (protein kinase C activators) does not influence GM-CSF receptor expression, suggesting that receptor upregulation by TNF is not mediated through activation of protein kinase C. On the other hand, the protein synthesis inhibitor cycloheximide abrogates receptor upregulation induced by TNF. In contrast to these findings in AML, TNF does not upregulate GM-CSF receptor numbers on blood granulocytes or monocytes. We conclude that TNF exerts positive effects on growth factor receptor expression of hematopoietic cells.
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PMID:Tumor necrosis factor regulates the expression of granulocyte-macrophage colony-stimulating factor and interleukin-3 receptors on human acute myeloid leukemia cells. 182 89

Segments critical to the activity of human granulocyte-macrophage colony-stimulating factor (GM-CSF) were identified by scanning deletion analysis and compared with the critical regions previously identified in the homologous mouse GM-CSF protein. Three of the four critical regions thus identified are in equivalent positions in their respective polypeptides, while a fourth critical region of each is uniquely located. To investigate whether unique critical regions are responsible for the observed species specificity of human and mouse GM-CSF, all critical regions were substituted into their opposite homologue. This identified one specific, but different, critical region in each homologue that could not be replaced. Further characterization of the nature of the species specificity of these two proteins was accomplished by the generation of a series of human/mouse GM-CSF hybrids. Each hybrid protein was assayed for specific activity on human- and mouse GM-CSF-dependent cell lines. Significant differences in the specific activity of these hybrids was observed, suggesting that different segments of each molecule interact with their respective receptors. Based on these two approaches, individual amino acids were identified that could provide, at least in part, the interactions between these protein ligands and their respective receptors. These residues are Thr-78 and Met-80 in human GM-CSF and Asp-92, Thr-98, and Asp-102 in mouse GM-CSF.
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PMID:Identification of critical amino acid residues in human and mouse granulocyte-macrophage colony-stimulating factor and their involvement in species specificity. 185 12

Polymorphonuclear leukocytes (PMN) constitutively synthesize various plasma membrane proteins including CR1(3) (CD35), CR3 (or Mac-1) alpha-chain (CD11b) and MHC class I. PMN are also able to up-regulate rapidly the expression of CR1 and CR3 to the plasma membrane in response to agonists such as FMLP. To determine whether constitutive PMN translation was static or up-regulatable, PMN were cultured in the presence or absence of the cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) for 8 h. CR1, CR3 and class I proteins immunoprecipitated from lysates of 35S-methionine pulse-labeled PMN were resolved by SDS-PAGE, fluorographed and quantified by densitometry. GM-CSF-treated PMN synthesized 4.5-fold more class I protein, 3.7-fold more CR1, 2.4-fold more CD11b and 3.4-fold more CR3 beta-chain (CD18), compared with untreated control cells. Actinomycin D treatment of replicate samples of PMN decreased the amount of these proteins synthesized by each group of PMN from 30 to 90%, implying that continued translation was required for the increases in protein synthesis. Nascent CR and class I proteins were inserted into the plasma membrane of PMN, thereby supplementing the molecules already expressed on the cell surface. In addition to these longer term effects of GM-CSF, we observed its acute up-regulatory effects on PMN. GM-CSF induced a five- to 12-fold increase in the expression of CR1 and CR3 on the PMN cell surface within 30 min. These increases were both dose- and time-dependent with maximum up-regulation occurring at 25 pM and at 30 min. In contrast to the long term biosynthetic events, this rapid up-regulation was not dependent on protein synthesis but was due instead to mobilization of CR from intracellular compartments similar to those up-regulated by FMLP. These results demonstrate that PMN can respond to microenvironmental stimuli such as GM-CSF both by rapidly up-regulating and increasing translation and expression of functionally important plasma membrane proteins.
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PMID:Granulocyte-macrophage colony-stimulating factor increases synthesis and expression of CR1 and CR3 by human peripheral blood neutrophils. 197 99

Colony-stimulating factors (CSFs) have important effects on mature myeloid cells in addition to their regulatory role in haemopoiesis. Exposure of neutrophils to granulocyte macrophage-CSF (GM-CSF) increases chemotaxis, phagocytosis and cytotoxicity and primes the cells for enhanced oxidative metabolism in response to stimuli, such as formylated oligopeptides derived from bacteria (f-Met-Leu-Phe) and endogenous activated complement components (C5a). GM-CSF induces time-dependent changes in neutrophil f-Met-Leu-Phe receptor number and affinity that correspond to changes in functional activity. The neutrophil IgA Fc receptor is also modulated by GM-CSF such that it develops a high affinity state and transduces a phagocytic signal. The ability to regulate the number and activity of mature myeloid effector cells in vivo establishes unique therapeutic opportunities in the area of infectious disease, cancer treatment, bone marrow transplantation and augmentation of host defence in immunodeficient patients.
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PMID:Responses of neutrophils to myeloid growth factors. 218 Jun 50


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