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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)

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin (IL)-3, and IL-5 stimulate DNA synthesis and proliferation and inhibit apoptosis in hematopoietic cells. Multiple signal pathways are activated by binding of these ligands to their receptors, which share a common beta subunit. Janus protein kinase 2 (Jak2) binds to the membrane proximal domain of the beta chain and is phosphorylated on receptor ligation. To explore the role of Jak2 in the regulation of specific signal transduction pathways, we constructed fusion proteins with a CD16 external domain, a CD7 transmembrane region, and a Jak2 cytoplasmic domain. This cytoplasmic domain consisted either of wild type Jak2 (CD16/Jak2-W) or Jak2 mutations with deletions of (a) the amino terminus (CD16/Jak2-N), (b) kinase-like domain (CD16/Jak2-B), (c) kinase domain (CD16/Jak2-C), or (d) amino-terminal and kinase-like domains, leaving the kinase domain (CD16/Jak-K) intact. In contrast to the CD16/Jak2-W fusion protein, which requires cross-linking for activation, CD16/Jak2-N, CD16/Jak2-B, and CD16/Jak2-K were constitutively phosphorylated, and they stimulated Shc phosphorylation and increased binding of STAT to DNA in Ba/F3 cells. Cell lines derived from IL-3-dependent Ba/F3 cells stably transfected with CD16/Jak2-W, CD16/Jak2-N, or CD16/Jak2-B mammalian expression vectors died at a rate similar to that of the parental cells on IL-3 deprivation. In contrast, CD16/Jak2-K cell lines exhibited increased expression of bcl-2 and pim-1 mRNA and maintained their viability when compared with control cell lines. Thus, activation of tyrosine phosphorylation by creating a CD16/Jak2-K fusion is sufficient to activate pathways that prevent cell death.
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PMID:The kinase domain of Jak2 mediates induction of bcl-2 and delays cell death in hematopoietic cells. 913 79

The human cell line, TF-1, was used to compare responses to interleukin 3 (IL-3), IL-5 and granulocyte-macrophage colony-stimulating factor (GM-CSF). TF-1 cells grew well in the presence of any one of the cytokines in early passages. However, the level of tyrosine phosphorylation was minimal in response to IL-5, and detection of a tyrosine phosphorylation signal required high concentrations of IL-5. When grown for longer periods of time in the presence of one of the cytokines, there were dramatic difference in the cells' responses. IL-3 or GM-CSF-grown cells showed only half of the original bioassay response to IL-5. However, cells grown in IL-5 alone kept the same response, and all cells showed the same response to IL-3 and GM-CSF. IL-5-grown cells also had an increased tyrosine phosphorylation signal, along with increased sensitivity to IL-5, yet there was no difference in an IL-5 bioassay. The relative level of detection of tyrosine phosphorylated JAK-2, STAT-5, SHC, and other substrates corresponded to the overall tyrosine phosphorylation signal. IL-5-grown cells had approximately 10-fold more IL-5 receptor alpha subunit message compared to IL-3-grown. These results suggest that response of TF-1 cells to IL-5 may be deceiving in that a good response in a bioassay can be observed with relatively little tyrosine phosphorylation, but an increase in tyrosine phosphorylation can be correlated with an increase in the expression of IL-5 receptor alpha subunit.
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PMID:Lack of correlation between growth of TF-1 cells and tyrosine phosphorylation signals in response to IL-3, IL-5 and GM-CSF. 932 13

Cytokine-mediated signaling pathways were studied in mouse dendritic cells (DC) by analysis of the activation pattern of STAT factors. Electrophoretic mobility shift assays were performed to detect STAT isoform-specific complexes. Granulocyte-macrophage colony-stimulating factor (GM-CSF) simultaneously induced complexes containing STAT1, STAT3, STAT5A, STAT5B and STAT6. In non-DC, a similar broad activation pattern of STAT factors by GM-CSF or other cytokines has not been observed so far. By comparison, in peritoneal macrophages, GM-CSF induced a complex with the properties of a truncated form of STAT5. Other cytokines tested on DC either failed to induce STAT factors [interleukin (IL)-1 beta, IL-2, IL-15], or activated the same STAT factors as observed in peritoneal macrophages (IL-4, IFN-gamma). Our results implicate a specific effect of GM-CSF on STAT signaling in DC which might account for the cell type-specific effect of this cytokine on development and function.
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PMID:Granulocyte-macrophage colony-stimulating factor induces a unique set of STAT factors in murine dendritic cells. 936 34

The granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor (GMR) is a heterodimeric receptor expressed by myeloid lineage cells. Binding of GM-CSF activates at least one receptor-associated tyrosine kinase, JAK2, and rapidly induces tyrosine phosphorylation of the GMR betac-chain (GMRbeta), but not the GMR alpha-chain (GMRalpha). To examine the role of GMRbeta tyrosine phosphorylaiton, each of the 8 tyrosine residues in the cytoplasmic domain of the human GMRbeta was mutated to phenylalanine (GMRbeta-F8), and this mutant receptor was expressed with wild-type GMRalpha in the interleukin-3-dependent murine hematopoietic cell line, Ba/F3. GM-CSF induced tyrosine phosphorylation of multiple cellular proteins in cells expressing GMRbeta-F8 , including JAK2 and STAT5. However, GM-CSF-induced tyrosine phosphorylation of both SHP2 and SHC was reduced or absent compared with wild-type. Next, a series of 8 receptors were generated, each containing only a single, restored, tyrosine residue. Tyrosine 577 was found to be sufficient to regenerate GM-CSF-dependent phosphorylation of SHC, and any of Y577, Y612, or Y695 was sufficient to regenerate GM-CSF-inducible phosphorylation of SHP2. Despite the signaling defect to SHC and SHP2, Ba/F3 cells expressing GMRbeta-F8 were still able to proliferate in response to 10 ng/mL of human GM-CSF, although mitogenesis was impaired compared with wild-type GMRbeta, and this effect was even more prominent at lower concentrations of GM-CSF (1 ng/mL). Overall, these results indicate that GMRbeta tyrosine residues are not necessary for activation of the JAK/STAT pathway or for proliferation, viability, or adhesion signaling in Ba/F3 cells, although tyrosine residues significantly affect the magnitude of the response. However, specific tyrosine residues are needed for activation of SHC and SHP2.
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PMID:Signaling functions of the tyrosine residues in the betac chain of the granulocyte-macrophage colony-stimulating factor receptor. 938 92

Cytokine-mediated inhibition of eosinophil apoptosis is a mechanism causing tissue eosinophilia. Previously published work suggested that activation of the Lyn-Ras-Raf-1-MAP kinase pathway is obligatory for prevention of eosinophil apoptosis by eosinophil hematopoietins. We demonstrate herein that activation of freshly isolated human blood eosinophils by granulocyte-macrophage colony-stimulating factor (GM-CSF) is associated with increased tyrosine phosphorylation of Jak2. The tyrosine kinase blocker, tyrphostin B42, prevented activation of Jak2 but not Lyn, suggesting that Jak2 is the specific target for tyrphostin B42 in eosinophils. In addition, since Lyn remained unaffected by tyrphostin B42, it is unlikely that Jak2 is required for Lyn activation in this model. To test whether tyrosine phosphorylation of Jak2 is linked to GM-CSF-mediated prolonged eosinophil survival, we determined the effect of tyrphostin B42 on eosinophil viability and apoptosis. Prevention of Jak2 activation by tyrphostin B42 was associated with the inability of GM-CSF to prevent eosinophil apoptosis. These data suggest that disruption of not only the Lyn-Ras-Raf-1-MAP kinase but also the Jak-STAT pathway blocks the ability of eosinophil survival factors to prevent apoptosis in eosinophils.
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PMID:Anti-apoptotic signals of granulocyte-macrophage colony-stimulating factor are transduced via Jak2 tyrosine kinase in eosinophils. 946 45

Granulocyte-macrophage colony-stimulating factor (GM-CSF) induces the proliferation and maturation of immature myeloid progenitor cells and primes mature cell function in phagocytes. To investigate whether the biochemical events following the binding of GM-CSF to its receptor are differentiation dependent we analysed GM-CSF mediated activation of the JAK 2-STAT 5 and MAP kinase pathways in undifferentiated HL-60 cells and HL-60 cells induced to differentiate with dimethyl sulphoxide (DMSO) or retinoic acid (RA). GM-CSF stimulated MAP kinase activation in both the undifferentiated and differentiated HL-60 cells. Activation of MAP kinase (expressed as a proportion of total cellular MAP kinase) was maximal at 5 min and of similar magnitude in both cell types. There was, however, a marked difference in the later kinetics of activation, with the response being transient in the undifferentiated cells and disappearing within 15 min, whereas it was prolonged and persisted for at least 60 min in the differentiated cells. GM-CSF mediated activation of STAT 5 was markedly increased (15-20-fold) after differentiation of HL-60 cells but the kinetics of activation did not change. The increase in STAT 5 activation was not due to a change in total cellular STAT 5 expression but correlated with increased JAK-2 protein levels. These data show that in the HL-60 cell model, differentiation modulates the activation of signalling molecules downstream of the GM-CSF receptor.
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PMID:Differentiation-linked changes in granulocyte-macrophage colony-stimulating factor receptor mediated signalling in the HL-60 promyelocytic cell line. 957 87

Cytokines manifest their function through regulation of gene expression. We searched for immediate-early cytokine responsive genes by the mRNA differential display technique using interleukin-3 (IL-3)-dependent OTT-1 cells, and have isolated a novel cDNA which encodes 210 amino acids and shows 87% amino acid identity to human SNAP-23 (synaptosomal-associated protein of 23 kD). The message for this protein (mouse SNAP-23) was induced in OTT-1 cells by IL-3, granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-5. The experiment using C-terminal deletion mutants of the common beta subunit (betac) of IL-3/GM-CSF/IL-5 receptors showed that expression of SNAP-23 was associated with the Ras-Raf-MAPK pathway, but not with the JAK-STAT pathway. Moreover, SNAP-23 was induced in response to a wide variety of cytokines, including IL-2, IL-3, IL-5, IL-10, stem cell factor, G-CSF, GM-CSF, leukemia inhibitory factor, and erythropoietin. Constitutive expression of SNAP-23 was seen in various tissues, including heart, lung, kidney, liver, spleen, and small intestine. Possible involvement of SNAP-23 in cytokine signal transduction is discussed.
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PMID:Induction of synaptosomal-associated protein-23 kD (SNAP-23) by various cytokines. 963 8

The high-affinity human granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor (GMR) consists of an alpha (GMRalpha) and a common beta (betac) subunit. The intracellular domain of betac has been extensively characterized and has been shown to be critical for the activation of both the JAK/STAT and MAP kinase pathways. The function of the intracellular domain of GMRalpha, however, is not as well characterized. To determine the role of this domain in GMR signaling, an extensive structure-function analysis was performed. Truncation mutants alpha362, alpha371, and alpha375 were generated, as well as the site-directed mutants alphaVQVQ and alphaVVVV. Although alpha375beta, alphaVQNQbeta, and alphaVVVVbeta stimulated proliferation in response to human GM-CSF, the truncation mutants alpha362beta and alpha371beta were incapable of transducing a proliferative signal. In addition, both alpha371 and alphaVVVV were expressed at markedly reduced levels, indicating the importance of residues 372 to 374 for proper protein expression. More importantly, we show that GMRalpha plays a direct role in the activation of the JAK/STAT pathway, and electrophoretic mobility shift assays (EMSA) indicate that both GMRalpha and betac play a role in determining the STAT5 DNA binding complex activated by the GMR. Thus, the intracellular domain of the human GMRalpha is important for activation of the JAK/STAT pathway and protein stabilization.
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PMID:Characterization of the role of the human granulocyte-macrophage colony-stimulating factor receptor alpha subunit in the activation of JAK2 and STAT5. 968 Mar 54

The high-affinity receptors for human granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are heterodimeric complexes consisting of cytokine-specific alpha subunits and a common signal-transducing beta subunit (hbetac). We have previously demonstrated the oncogenic potential of this group of receptors by identifying constitutively activating point mutations in the extracellular and transmembrane domains of hbetac. We report here a comprehensive screen of the entire hbetac molecule that has led to the identification of additional constitutive point mutations by virtue of their ability to confer factor independence on murine FDC-P1 cells. These mutations were clustered exclusively in a central region of hbetac that encompasses the extracellular membrane-proximal domain, transmembrane domain, and membrane-proximal region of the cytoplasmic domain. Interestingly, most hbetac mutants exhibited cell type-specific constitutive activity, with only two transmembrane domain mutants able to confer factor independence on both murine FDC-P1 and BAF-B03 cells. Examination of the biochemical properties of these mutants in FDC-P1 cells indicated that MAP kinase (ERK1/2), STAT, and JAK2 signaling molecules were constitutively activated. In contrast, only some of the mutant beta subunits were constitutively tyrosine phosphorylated. Taken together, these results highlight key regions involved in hbetac activation, dissociate hbetac tyrosine phosphorylation from MAP kinase and STAT activation, and suggest the involvement of distinct mechanisms by which proliferative signals can be generated by hbetac.
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PMID:Saturation mutagenesis of the beta subunit of the human granulocyte-macrophage colony-stimulating factor receptor shows clustering of constitutive mutations, activation of ERK MAP kinase and STAT pathways, and differential beta subunit tyrosine phosphorylation. 973 Oct 57

CrkL is an adapter protein comprising Src homology (SH) 2 and SH3 domains. We investigated the molecule(s) associated with CrkL in factor-dependent cell lines. In the granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent cell lines TF-1 and UT-7, an approximately 95-kDa tyrosine-phosphorylated protein was precipitated along with CrkL after GM-CSF stimulation. The same protein was also observed when we used the erythropoietin (EPO)-dependent cell line UT-7/EPO, in an EPO stimulation-dependent manner. We identified it as STAT5 (signal transducer and activator of transcription 5, 96 kDa) by STAT5-specific antibodies. The direct binding of the SH2 domain of CrkL to STAT5 was demonstrated in far Western blotting and pull-down experiments using the glutathione S-transferase (GST) fusion construct CrkL-SH2. The addition of the oligopeptide containing phosphotyrosine 694 in STAT5A impaired the association between GST-CrkL-SH2 and STAT5. Furthermore, in a gel shift assay using prolactin-inducible element (PIE) as the probe, the DNA binding activity of STAT5 was inhibited by the interaction with GST-CrkL-SH2 in vitro. Finally, we found that STAT5 associated with CrkL did not bind to PIE sequence. These results suggest that CrkL participates in the Janus kinase (JAK)-STAT pathway by direct association with STAT5.
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PMID:Association of CrkL with STAT5 in hematopoietic cells stimulated by granulocyte-macrophage colony-stimulating factor or erythropoietin. 983 84


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