UNIPROT:P04141 - FACTA Search

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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)

Growth factor receptors play an important role in hematopoiesis. In order to further understand the mechanisms directing the expression of these key regulators of hematopoiesis, we initiated a study investigating the transcription factors activating the expression of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor alpha gene. Here, we demonstrate that the human GM-CSF receptor alpha promoter directs reporter gene activity in a tissue-specific fashion in myelomonocytic cells, which correlates with its expression pattern as analyzed by reverse transcription PCR. The GM-CSF receptor alpha promoter contains an important functional site between positions -53 and -41 as identified by deletion analysis of reporter constructs. We show that the myeloid and B cell transcription factor PU.1 binds specifically to this site. Furthermore, we demonstrate that a CCAAT site located upstream of the PU.1 site between positions -70 and -54 is involved in positive-negative regulation of the GM-CSF receptor alpha promoter activity. C/EBP alpha is the major CCAAT/enhancer-binding protein (C/EBP) form binding to this site in nuclear extracts of U937 cells. Point mutations of either the PU.1 site or the C/EBP site that abolish the binding of the respective factors result in a significant decrease of GM-CSF receptor alpha promoter activity in myelomonocytic cells only. Furthermore, we demonstrate that in myeloid and B cell extracts, PU.1 forms a novel, specific, more slowly migrating complex (PU-SF) when binding the GM-CSF receptor alpha promoter PU.1 site. This is the first demonstration of a specific interaction with PU.1 on a myeloid PU.1 binding site. The novel complex is distinct from that described previously as binding to B cell enhancer sites and can be formed by addition of PU.1 to extracts from certain nonmyeloid cell types which do not express PU.1, including T cells and epithelial cells, but not from erythroid cells. Furthermore, we demonstrate that the PU-SF complex binds to PU.1 sites found on a number of myeloid promoters, and its formation requires an intact PU.1 site adjacent to a single-stranded region. Expression of PU.1 in nonmyeloid cells can activate the GM-CSF receptor alpha promoter. Deletion of the amino-terminal region of PU.1 results in a failure to form the PU-SF complex and in a concomitant loss of transactivation, suggesting that formation of the PU-SF complex is of functional importance for the activity of the GM-CSF receptor alpha promoter. Finally, we demonstrate that C/EBP alpha can also active the GM-CSF receptor alpha promoter in nonmyeloid cells. These results suggest that PU.1 and C/EBP alpha direct the cell-type-specific expression of GM-CSF receptor alpha, further establish the role of PU.1 as a key regulator of hematopoiesis, and point to C/EBP alpha as an additional important factor in this process.
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PMID:PU.1 (Spi-1) and C/EBP alpha regulate expression of the granulocyte-macrophage colony-stimulating factor receptor alpha gene. 756 36

Macrosialin is a transmembrane glycoprotein that is highly expressed in macrophages. In the present studies, macrosialin mRNA levels are shown to be markedly up-regulated during macrophage differentiation of bone marrow progenitor cells in response to macrophage colony-stimulating factor and granulocyte-macrophage colony-stimulating factor. To investigate the mechanisms responsible for regulation of macrosialin expression, we have isolated the macrosialin gene and performed an initial analysis of its transcriptional regulatory elements. The macrosialin promoter and 7.0 kilobase pairs of 5'-flanking information direct high levels of reporter gene activity in monocyte/macrophage-like cells, but little or no expression in nonmyeloid cells. This pattern of expression is dependent on regulatory elements located between -7.0 and -2.5 kilobase pairs from the transcriptional start site that exhibit strong enhancer activity in macrophages and repressor activity in nonmyeloid cells. Analysis of the proximal macrosialin promoter indicates that combinatorial interactions between at least four classes of transcriptional activators, including PU.1/Spi-1 and members of the AP-1 family are required for basal promoter function. PU.1/Spi-1 and c-Jun act synergistically to activate the macrosialin promoter in a nonmyeloid cell line, suggesting that combinatorial interactions between these proteins are involved in regulating macrosialin expression during macrophage differentiation.
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PMID:The macrosialin promoter directs high levels of transcriptional activity in macrophages dependent on combinatorial interactions between PU.1 and c-Jun. 947

PU.1 is a unique regulatory protein required for the generation of both the innate and the adaptive immune system. It functions exclusively in a cell-intrinsic manner to control the development of granulocytes, macrophages, and B and T lymphocytes. We demonstrate that mutation of the PU.1 gene causes a severe reduction in myeloid (granulocyte/macrophage) progenitors. PU.1 -/- myeloid progenitors can proliferate in vitro in response to the multilineage cytokines interleukin-3 (IL-3), IL-6 and stem cell factor but are unresponsive to the myeloid-specific cytokines granulocyte-macrophage colony-stimulating factor (GM-CSF), G-CSF and M-CSF. The failure of PU.1 -/- progenitors to respond to G-CSF is bypassed by transient signaling with IL-3. In the presence of IL-3 and G-CSF, PU.1 -/- progenitors can differentiate into granulocytic precursors containing myeloperoxidase-positive granules. Thus PU.1 is not essential for specification of granulocytic precursors, but is required for their further differentiation. The failure of PU.1 -/- progenitors to respond to M-CSF is due to lack of c-fms gene transcription. Transduction of c-fms into PU.1 -/- myeloid progenitors bypasses the block to M-CSF-dependent proliferation but does not induce detectable macrophage differentiation. Therefore, PU. 1 appears to be essential for specification of monocytic precursors. Importantly, retroviral transduction of PU.1 into mutant progenitors restores responsiveness to myeloid-specific cytokines and development of mature granulocytes and macrophages. Thus PU.1 controls myelopoiesis by regulating both proliferation and differentiation pathways.
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PMID:PU.1 regulates both cytokine-dependent proliferation and differentiation of granulocyte/macrophage progenitors. 968 12

High-affinity receptors for interleukin-3 (IL-3), IL-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF) are composed of two distinct subunits, a ligand-specific chain and a common beta chain (betac). Whereas the mouse has two homologous beta subunits (betac and betaIL-3), in humans, only a single beta chain is identified. We describe here the isolation and characterization of the gene encoding the human IL-3/IL-5/GM-CSF receptor beta subunit. The gene spans about 25 kb and is divided into 14 exons, a structure very similar to that of the murine betac/betaIL-3 genes. Surprisingly, we also found the remnants of a second betac chain gene directly downstream of betac. We identified a functional promoter that is active in the myeloid cell lines U937 and HL-60, but not in HeLa cells. The proximal promoter region, located from -103 to +33 bp, contains two GGAA consensus binding sites for members of the Ets family. Single mutation of those sites reduces promoter activity by 70% to 90%. The 5' element specifically binds PU.1, whereas the 3' element binds a yet-unidentified protein. These findings, together with the observation that cotransfection of PU.1 and other Ets family members enhances betac promoter activity in fibroblasts, reinforce the notion that GGAA elements play an important role in myeloid-specific gene regulation.
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PMID:Cloning and characterization of the human interleukin-3 (IL-3)/IL-5/ granulocyte-macrophage colony-stimulating factor receptor betac gene: regulation by Ets family members. 980 57

We previously noted that the initial receptor by which murine osteoclast precursors bind matrix is the integrin alphav beta5 and that granulocyte-macrophage colony-stimulating factor (GM-CSF) decreases expression of this heterodimer by suppressing transcription of the beta5 gene. We herein report cloning of the beta5 integrin gene promoter and identification of a GM-CSF-responsive sequence. A 13-kilobase (kb) genomic fragment containing part of the beta5 gene was isolated by screening a mouse genomic library with a probe derived from the most 5'-end of a murine beta5 cDNA. A combination of primer extension and S1 nuclease studies identifies two transcriptional start sites, with the major one designated +1. A 1-kb subclone containing sequence -875 to + 110 is transcriptionally active in a murine myeloid cell line. This 1-kb fragment contains consensus binding sequences for basal (Sp1), lineage-specific (PU.1), and regulatable (signal transducer and activator of transcription) transcription factors. Reflecting our earlier findings, promoter activity is repressed in transfected myeloid cells treated with GM-CSF. Using deletion mutants, we localized a 109-base pair (bp) promoter region responsible for GM-CSF-inhibited beta5 transcription. We further identified a 19-bp sequence within the 109-bp region that binds GM-CSF-induced nuclear proteins by gel shift/competition assays. Mutation of the 19-bp sequence not only ablates its capacity to bind nuclear proteins from GM-CSF-treated cells, in vitro, but the same mutation, when introduced in the 1-kb promoter, abolishes its ability to respond to GM-CSF treatment. Northern analysis demonstrates that cycloheximide treatment abrogates the capacity of GM-CSF to decrease beta5 mRNA levels. In summary, we have identified a 19-bp cis-element mediating GM-CSF-induced down-regulation of beta5 by a mechanism requiring protein synthesis.
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PMID:Cloning of the murine beta5 integrin subunit promoter. Identification of a novel sequence mediating granulocyte-macrophage colony-stimulating factor-dependent repression of beta5 integrin gene transcription. 988 May 8

Mice homozygous for the disruption of the PU.1 (Spi-1) gene do not produce mature macrophages. In determining the role of PU.1 in macrophage differentiation, the present study investigated whether or not there was commitment to the monocytic lineage in the absence of PU.1. Early PU.1-/- myeloid colonies were generated from neonate liver under conditions that promote primarily macrophage and granulocyte/macrophage colonies. These PU.1-/- colonies were found to contain cells with monocytic characteristics as determined by nonspecific esterase stain and the use of monoclonal antibodies that recognize early monocyte precursors, including Moma-2, ER-MP12, ER-MP20, and ER-MP58. In addition, early myeloid cells could be grown from PU.1-/- fetal liver cultures in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF). Similar to the PU.1 null colonies, the GM-CSF-dependent cells also possessed early monocytic characteristics, including the ability to phagocytize latex beads. The ability of PU.1-/- progenitors to commit to the monocytic lineage was also verified in vivo by flow cytometry and cytochemical analysis of primary neonate liver cells. The combined data shows that PU.1 is absolutely required for macrophage development after commitment to this lineage.
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PMID:Commitment to the monocytic lineage occurs in the absence of the transcription factor PU.1. 1021 79

The ets-family transcription factor PU.1 is required for the proper development of both myeloid and lymphoid progenitors. We used PU. 1-deficient animals to examine the role of PU.1 during dendritic cell development. PU.1(-/-)animals produce lymphoid-derived dendritic cells (DC): low-density class II major histocompatibility complex [MHC-II(+)] CD11c(+) CD8alpha(+) DEC-205(+). But they lack myeloid-derived DC: low-density MHC-II(+) CD11c(+) CD8alpha(-) DEC-205(-). PU.1(-/-) embryos also lack progenitors capable of differentiating into myeloid DC in response to granulocyte-macrophage colony-stimulating factor plus interleukin-4. The appearance of lymphoid DC in developing PU.1(-/-)thymus was initially delayed, but this population recovered to wild type (WT) levels upon organ culture of isolated thymic lobes. PU. 1(-/-)lymphoid DC were functionally equivalent to WT DC for stimulating T-cell proliferation in mixed lymphocyte reactions. These results demonstrate that PU.1 is required for the development of myeloid DC but not lymphoid DC.
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PMID:PU.1 is required for myeloid-derived but not lymphoid-derived dendritic cells. 1064 99

The genes encoding Hoxa9 and Meis1 are transcriptionally coactivated in a subset of acute myeloid leukemia (AML) in mice. In marrow reconstitution experiments, coexpression of both genes produces rapid AML, while neither gene alone generates overt leukemia. Although Hoxa9 and Meis1 can bind DNA as heterodimers, both can also heterodimerize with Pbx proteins. Thus, while their coactivation may result from the necessity to bind promoters as heterodimers, it may also result from the necessity of altering independent biochemical pathways that cooperate to generate AML, either as monomers or as heterodimers with Pbx proteins. Here we demonstrate that constitutive expression of Hoxa9 in primary murine marrow immortalizes a late myelomonocytic progenitor, preventing it from executing terminal differentiation to granulocytes or monocytes in the presence of granulocyte-macrophage colony-stimulating factor (GM-CSF) or interleukin-3. This immortalized phenotype is achieved in the absence of endogenous or exogenous Meis gene expression. The Hoxa9-immortalized progenitor exhibited a promyelocytic transcriptional profile, expressing PU.1, AML1, c-Myb, C/EBP alpha, and C/EBP epsilon as well as their target genes, the receptors for GM-CSF, G-CSF, and M-CSF and the primary granule proteins myeloperoxidase and neutrophil elastase. G-CSF obviated the differentiation block of Hoxa9, inducing neutrophilic differentiation with accompanying expression of neutrophil gelatinase B and upregulation of gp91phox. M-CSF also obviated the differentiation block, inducing monocytic differentiation with accompanying expression of the macrophage acetyl-low-density lipoprotein scavenger receptor and F4/80 antigen. Versions of Hoxa9 lacking the ANWL Pbx interaction motif (PIM) also immortalized a promyelocytic progenitor with intrinsic biphenotypic differentiation potential. Therefore, Hoxa9 evokes a cytokine-selective block in differentiation by a mechanism that does not require Meis gene expression or interaction with Pbx through the PIM.
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PMID:Hoxa9 immortalizes a granulocyte-macrophage colony-stimulating factor-dependent promyelocyte capable of biphenotypic differentiation to neutrophils or macrophages, independent of enforced meis expression. 1075 11

The transcription factor PU.1 is required for normal blood cell development. PU.1 regulates the expression of a number of crucial myeloid genes, such as the macrophage colony-stimulating factor (M-CSF) receptor, the granulocyte colony-stimulating factor (G-CSF) receptor, and the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor. Myeloid cells derived from PU.1(-/-) mice are blocked at the earliest stage of myeloid differentiation, similar to the blast cells that are the hallmark of human acute myeloid leukemia (AML). These facts led us to hypothesize that molecular abnormalities involving the PU.1 gene could contribute to the development of AML. We identified 10 mutant alleles of the PU.1 gene in 9 of 126 AML patients. The PU.1 mutations comprised 5 deletions affecting the DNA-binding domain, and 5 point mutations in 1) the DNA-binding domain (2 patients), 2) the PEST domain (2 patients), and 3) the transactivation domain (one patient). DNA binding to and transactivation of the M-CSF receptor promoter, a direct PU.1 target gene, were deficient in the 7 PU.1 mutants that affected the DNA-binding domain. In addition, these mutations decreased the ability of PU.1 to synergize with PU.1-interacting proteins such as AML1 or c-Jun in the activation of PU.1 target genes. This is the first report of mutations in the PU.1 gene in human neoplasia and suggests that disruption of PU.1 function contributes to the block in differentiation found in AML patients.
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PMID:Heterozygous PU.1 mutations are associated with acute myeloid leukemia. 1459 9

Severely impaired pulmonary microbial clearance was observed in granulocyte-macrophage colony-stimulating factor (GM-CSF)-deficient mice. To determine mechanisms by which GM-CSF mediates lung host defense, FcgammaR-mediated phagocytosis (opsonophagocytosis) by alveolar macrophages (AMs) was assessed in GM-CSF-sufficient (GM(+/+)) and -deficient (GM(-/-)) mice and in GM(-/-) mice expressing GM-CSF only in the lungs from a surfactant protein C (SPC) promoter (SPC-GM(+/+)/GM(-/-)). Opsonophagocytosis by GM(-/-) AMs was severely impaired and was restored by pulmonary GM-CSF expression in vivo or by PU.1 expression in vitro. Defective opsonophagocytosis by GM(-/-) AMs was associated with decreased FcgammaR expression. Because interferon-gamma (IFN-gamma) augments macrophage FcgammaR levels, the role of GM-CSF/PU.1 in the regulation of AM FcgammaR expression by IFN-gamma was assessed during adenoviral lung infection. Adenoviral infection stimulated IFN-gamma production and augmented FcgammaR levels on AMs in GM-CSF-expressing but not GM(-/-) mice. However, IFN-gamma exposure ex vivo stimulated FcgammaR expression on GM(-/-) AMs. Because interleukin-18 (IL-18) and IL-12 stimulate IFN-gamma production during adenoviral infection, their role in GM-CSF/PU.1 regulation of IFN-gamma-augmented FcgammaR expression on AMs was assessed. Adenoviral infection stimulated IL-18 and IL-12 production in GM-CSF-expressing mice, but both were markedly reduced or absent in GM(-/-) mice. IL-18 expression by GM(-/-) AMs was severely impaired and was restored by pulmonary GM-CSF expression in vivo or by PU.1 expression in vitro. Pulmonary administration of IL-18 in GM(-/-) mice stimulated IFN-gamma production and restored FcgammaR expression on AMs. These results show that GM-CSF, via PU.1, regulates constitutive AM FcgammaR expression and opsonophagocytosis and is required for the IFN-gamma-dependent regulation of AM FcgammaR expression, enabling AMs to release IL-18/IL-12 during lung infection.
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PMID:GM-CSF, via PU.1, regulates alveolar macrophage Fcgamma R-mediated phagocytosis and the IL-18/IFN-gamma -mediated molecular connection between innate and adaptive immunity in the lung. 1239 86

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