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)

The kinetics of 5-lipoxygenase (5-LO) activation in human neutrophils was compared with that of arachidonic acid (AA) release and leukotriene (LT) B4 synthesis, and the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on these processes was examined. The soluble agonists N-formyl-Met-Leu-Phe and platelet-activating factor stimulated 5-LO activity, which peaked within 10 s and then rapidly declined. At all time points investigated, 5-LO activity was greater in GM-CSF-treated neutrophils. The release of AA was detectable only in GM-CSF-treated neutrophils and peaked 1 min after the agonist stimulation. Accordingly, synthesis of LTB4 was detected only in GM-CSF-treated neutrophils. By comparison, 100 nM of ionomycin induced a greater and sustained activation of 5-LO, resulting in a greater synthesis of LTB4. These results show that 5-LO activation is immediate and transient in response to soluble agonists and that temporal dissociation with the release of AA limits LTB4 synthesis.
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PMID:Kinetics of 5-lipoxygenase activation, arachidonic acid release, and leukotriene synthesis in human neutrophils: effects of granulocyte-macrophage colony-stimulating factor. 802 23

High-affinity receptors for granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin 3, and interleukin 5 consist of ligand-specific alpha chains (low-affinity subunits) and a common beta chain (beta c) that converts each complex to a high-affinity form. Although beta c alone has no detectable cytokine-binding activity, amino acid substitutions for Glu-21 of human GM-CSF significantly reduce high-affinity but not low-affinity binding, implying that beta c interacts directly with GM-CSF during formation of the high-affinity receptor but only in the presence of the alpha chain. A potential GM-CSF-binding determinant was identified in the second hemopoietin domain of beta c, and the role of individual residues within this region was investigated by determining the ability of mutated beta c chains to confer high-affinity binding when coexpressed with the alpha subunit of the GM-CSF receptor in COS cells. Substitutions involving Met-363, Arg-364, Tyr-365, and Glu-366 did not affect high-affinity binding. However, substitution of His-367 by lysine or glutamine abolished high-affinity binding, suggesting that this residue may form an important part of the high-affinity GM-CSF-binding determinant. Consistent with the loss of high-affinity binding, higher concentrations of human GM-CSF were required to stimulate proliferation of CTLL-2 cell lines transfected with cDNAs for GM-CSF receptor alpha chain and His-367 beta c mutant than those expressing GM-CSF receptor alpha subunit and beta c wild type.
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PMID:Histidine-367 of the human common beta chain of the receptor is critical for high-affinity binding of human granulocyte-macrophage colony-stimulating factor. 827 75

Neutrophil apoptosis leads to macrophage ingestion of intact senescent neutrophils. This may represent a neutrophil removal mechanism that is important both in the control of inflammatory tissue injury and for the normal resolution processes of inflammation. Because apoptosis is likely to be a key control process in cell and tissue homeostasis, a number of inflammatory mediators were tested for their ability to modulate the rate of apoptosis in populations of neutrophils aging in culture. Endotoxic lipopolysaccharide, human recombinant complement factor 5a, and human recombinant granulocyte-macrophage colony-stimulating factor all markedly inhibited the rate of neutrophil apoptosis in a concentration-dependent fashion, without inducing necrosis (as assessed by trypan blue exclusion). This inhibitory effect on the rate of neutrophil apoptosis was shown by morphological criteria and confirmed by gel electrophoresis of extracted DNA. Inhibition of apoptosis of aging neutrophil populations was associated with prolongation of the functional life span of the population as assessed by the ability of neutrophils to spread on glass surfaces, to polarize in response to deliberate stimulation with N-formyl-Met-Leu-Phe (fMLP), and to release the granule enzyme marker myeloperoxidase on fMLP stimulation. These observations show that inflammatory mediators prolong the functional life span of neutrophils through modulation of apoptosis. Further elucidation of these mechanisms will lead to a better understanding of the processes controlling neutrophil residence and function in inflamed tissues and may provide further insights into the molecular mechanisms of apoptosis, which is of widespread importance in tissue biology.
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PMID:Inhibition of apoptosis and prolongation of neutrophil functional longevity by inflammatory mediators. 840 50

Recombinant human granulocyte-macrophage colony-stimulating factor (GM-CSF) can be expressed in yeast, bacteria, or mammalian cells. Expression in each system results in a protein that differs, to a varying extent, from native GM-CSF. Like the native protein, yeast-expressed GM-CSF is glycosylated and has 127 amino acids, but differs from native GM-CSF in molecular mass and in the substitution of leucine for proline at position 23. GM-CSF expressed in Escherichia coli bacteria is not glycosylated, has six fewer amino acids than the native protein, and an extra methionine at position 1. A review of laboratory studies shows that these differences in physiochemical properties result in variations in the pharmacokinetics, biologic activity, and immunogenicity of GM-CSF expressed in different host cells. These variations may lead to an increased clinical toxicity with GM-CSF expressed in E coli versus that produced in yeast. A total of 32 clinical trials were reviewed to determine the relative frequency of adverse events in patients treated with GM-CSF expressed in E coli versus that expressed in yeast. In general, the median reported frequency of adverse events was higher in patients treated with E coli-derived GM-CSF. The median frequencies of fluid retention, dyspnea, fever, myalgias/bone pain/joint pain, and rash were 8.3%, 13.4%, 21.7%, 16%, and 14.3%, respectively, in patients receiving GM-CSF expressed in yeast, versus 18.4%, 55.2%, 40.7%, 28.5%, and 12.5%, respectively, in patients treated with GM-CSF expressed in E coli. Thus data in the literature support the view that the GM-CSF expression system influences the pharmacokinetic properties, biologic activity, and clinical toxicity of GM-CSF.
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PMID:Clinical properties of yeast-derived versus Escherichia coli-derived granulocyte-macrophage colony-stimulating factor. 845 48

Interleukin 6 is a 184-aa polypeptide postulated to belong to the class of helical cytokines. We built a three-dimensional model of human interleukin 6 based on the similarity of its hydrophobicity pattern with that of other cytokines and on the x-ray structure of growth hormone, interleukin 2, interleukin 4, interferon beta, and granulocyte-macrophage colony-stimulating factor. The resulting model is a bundle of four alpha-helices and suggests possible alternative conformations for the 9 C-terminal amino acids; in this region, the importance of Arg-182 and Met-184 for biological activity has been demonstrated [Lutticken, C., Kruttgen, A., Moller, C., Heinrich, P.C. & Rose-John, S. (1991) FEBS Lett. 282, 265-267]. Therefore, we generated a large collection of single-amino acid variants in residues 175-181. Analysis of their biological activity in two systems and the receptor binding properties of a subset of the mutants indicates that the entire region is involved in forming the receptor binding surface and supports the hypothesis that this region does not assume an alpha-helical conformation. Remarkably, we also found a mutant with receptor affinity and biological activity much higher than wild type; the potential therapeutical value of this finding is discussed.
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PMID:Saturation mutagenesis of the human interleukin 6 receptor-binding site: implications for its three-dimensional structure. 848 22

Bone marrow (BM) stromal cells are required for normal hematopoiesis. A number of soluble factors secreted by these cells that mediate hematopoiesis have been characterized. However, the mechanism of hematopoiesis cannot be explained solely by these known factors, and the existence of other, still unknown stromal factors has been postulated. We showed that hepatocyte growth factor (HGF) is one such cytokine produced by human BM stromal cells. BM stromal cells were shown to constitutively produce HGF and also to express the c-MET/HGF receptor. The production of HGF was enhanced by addition of heparin and phorbol ester. Dexamethasone and tumor growth factor-beta (TGF-beta) inhibited the production of HGF. Interleukin-1 alpha (IL-1 alpha) tumor necrosis factor-alpha (TNF-alpha), and N6,2'-o-dibutyryl-adenosine-3':5'-cyclic monophosphate (dbc-AMP) showed no obvious influence on HGF production. Western blot analysis of HGF derived from BM stromal cells showed two bands at 85 and 28 kD corresponding to native and variant HGF, respectively. Addition of recombinant HGF significantly promoted the formation of burst-forming unit-erythroid (BFU-E) and colony-forming unit-granulocyte erythroid macrophage (CFU-GEM) by BM mononuclear cells in the presence of erythropoietin and granulocyte-macrophage colony-stimulating factor (GM-CSF), but the formation of CFU-GM was not modified. However, HGF had no effects on colony formation by purified CD34+ cells. Within BM mononuclear cells, c-MET was expressed on a proportion of cells (CD34-, CD33+, CD13+, CD14+, and CD15+), but was not found on CD34+ cells. We conclude that HGF is constitutively produced by BM stromal cells and that it enhances hematopoiesis. In addition, expression of c-MET on the stromal cells suggests the presence of an autocrine mechanism, operating through HGF, among stromal cells.
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PMID:Hepatocyte growth factor is constitutively produced by human bone marrow stromal cells and indirectly promotes hematopoiesis. 905 37

Granulocyte apoptosis is an important mechanism underlying the removal of redundant neutrophils from an inflammatory focus. The ability of many proinflammatory agents to impede this event suggests that such agents act not only in a priming or secretagogue capacity but also increase neutrophil longevity by delaying apoptosis. We have examined whether this hypothesis holds true for all neutrophil priming agents, in particular tumor necrosis factor-alpha (TNF-alpha), which has been variably reported to either induce, delay, or have no effect on neutrophil apoptosis. After 20 hours coincubation TNF-alpha inhibited neutrophil apoptosis; however, more detailed analysis demonstrated its ability to promote apoptosis in a subpopulation of cells at earlier (2 to 8 hours) times. Formyl-Met-Leu-Phe, platelet-activating factor, inositol hexakisphosphate, lipopolysaccharide, leukotriene B4, and granulocyte-macrophage colony-stimulating factor all inhibited apoptosis at 6 and 20 hours. The early proapoptotic effect of TNF-alpha was concentration-dependent (EC50 2.8 ng/mL), abolished by TNF-alpha neutralizing antibody, and was not associated with any change in cell viability or recovery. Of relevance to the inflamed site, the ability of TNF-alpha to accelerate apoptosis was lost if neutrophils were primed with 1 micromol/L PAF or aged for 6 hours before TNF-alpha addition. The TNFR55-selective TNF-alpha mutants (E146K, R32W-S86T) induced neutrophil apoptosis but with a potency 14-fold lower than wild-type TNF-alpha. Although the TNFR75-selective mutant (D143F) did not induce apoptosis, blocking antibodies to both receptor subtypes abolished TNF-alpha-stimulated apoptosis. Hence, TNF-alpha has the unique ability to induce apoptosis in human neutrophils via a mechanism where TNFR75 facilitates the dominant TNFR55 death effect. This may be an important mechanism controlling neutrophil longevity and clearance in vivo.
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PMID:Regulation of neutrophil apoptosis by tumor necrosis factor-alpha: requirement for TNFR55 and TNFR75 for induction of apoptosis in vitro. 932 45

Tumor necrosis factor-alpha (TNF-alpha) induces a rapid increase in polymorphonuclear leukocyte (PMN) polyamine content which appears to be required for optimal priming of the respiratory burst. The objective of the present study was to determine whether inhibition of polyamine biosynthesis modifies PMN responses to lipopolysaccharide (LPS), granulocyte-macrophage colony-stimulating factor (GM-CSF), or granulocyte colony-stimulating factor (G-CSF). Treatment with alpha-difluoromethylornithine (DFMO), a selective inhibitor of the rate-limiting biosynthetic enzyme ornithine decarboxylase, produced dose-dependent inhibition of the respiratory burst in PMNs that were primed by these agents and subsequently activated by formyl-Met-Leu-Phe (fMLP). However, DFMO did not significantly inhibit fMLP-stimulated superoxide generation or alter the induction of PMN adhesion and interleukin-1 beta (IL-1 beta) mRNA expression by LPS or GM-CSF. Antagonism of priming by DFMO correlated with a dose-dependent attenuation of fMLP-induced intracellular Ca2+ mobilization (r > or = 0.96). Since Ca2+ plays an important role in modulating the respiratory burst in primed PMNs, this could, in part, account for the selective effects of DFMO.
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PMID:An inhibitor of ornithine decarboxylase antagonizes superoxide generation by primed human polymorphonuclear leukocytes. 936 91

PIXY321, a human cytokine analog genetically engineered by the fusion of granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3), was expressed in yeast under the control of the alcohol dehydrogenase 2 (ADH2) promoter and the alpha-mating factor expression system. To provide the material necessary for the evaluation of PIXY321 in clinical trials, the production was scaled up to the 1200-1 scale and the PIXY321 molecule isolated by four successive steps of ion-exchange chromatography. Multiple heterogeneities, due to the presence of different patterns of glycosylation as well as multiple amino acid sequences at both N and C termini, were characterized on the purified molecule using complementary analytical techniques including electrophoresis, liquid chromatography and electrospray mass spectrometry. Four different N-terminal sequences were identified but simplified to a reproducible ratio of two sequences, the mature form and a form starting at Ala3, by adjustment of the process conditions. Molecules lacking 1-6 residues at the C-terminus were identified and their relative frequencies quantified. Amino acid modifications, such as three oxidized Met residues at positions 79, 141 and 187 and one deamidated Asn residue at position 176, were detected at low level. Microheterogeneities in glycosylation were characterized on four different sites, one located in the GM-CSF portion and three in the IL-3 portion of the molecule. The sites were shown to be differentially occupied and to carry 0-10 mannose residues according to their location in the sequence. Precise measurement of the heterogeneities at the molecular level were used to tune the process conditions and ensure reproducibility of the clinical product between lots.
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PMID:Characterization of the microheterogeneities of PIXY321, a genetically engineered granulocyte-macrophage colony-stimulating factor/interleukin-3 fusion protein expressed in yeast. 949 56

It was recently reported that transgenic expression in the liver of truncated human Met renders hepatocytes constitutively resistant to apoptosis and reproducibly permits their immortalization. The derived stable cell lines (MMH from Met murine hepatocyte) are highly differentiated and nontransformed. In this report, the capacity of MMHs to support in vitro hematopoiesis is characterized. By reverse-transcription polymerase chain reaction, the expression by MMHs of cytokines involved in the survival and self-renewal of early progenitor cells (stem cell factor and FLT3 ligand) as well as those acting at different stages of progenitor differentiation (interleukin [IL] 1beta, IL-3, leukemia inhibitory factor, IL-6, granulocyte-macrophage colony-stimulating factor, granulocyte colony-stimulating factor, macrophage colony-stimulating factor, and thrombopoietin) was shown. A ribonuclease protection assay further substantiated the presence of at least six cytokine transcripts in MMH lines. Cocultures between MMH layers and progenitor-enriched fetal liver hematopoietic cells resulted in a 40-fold to 80-fold expansion of total hematopoietic cells and in a 2.5-fold expansion of clonogenic progenitors after 1 to 2 weeks. Hematopoiesis was maintained for up to 6 weeks with formation of typical cobblestone cell areas and continuous differentiation of precursor into cells at various degrees of maturation. At 5 weeks of coculture, clonogenic progenitors were maintained at 20% of the input level in coculture with embryonic-derived hepatocytes, showing the ability of hepatocyte feeder layer to support survival and possibly self-renewal of clonogenic progenitors. Therefore, the data emphasize a direct role of the hepatocyte in sustaining hematopoietic cell proliferation and differentiation.
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PMID:Hematopoietic support and cytokine expression of murine-stable hepatocyte cell lines (MMH). 982 30


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