Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The serum-free mouse embryo (SFME) cell line, derived in serum-free medium from 16-day-old mouse embryos, exhibits unique properties. SFME cells grow indefinitely in culture without senescence, require epidermal growth factor (EGF) or fibroblast growth factor (FGF) for survival and are growth-inhibited by serum. The cell line expresses glial fibrillary acidic protein (GFAP) in response to transforming growth factor beta or serum and cells with similar properties can be isolated directly from brain. Culture of SFME cells with leukemia inhibitory factor (LIF), a peptide implicated in neural tissue development, also resulted in expression of GFAP. Other peptides that share signal transduction mechanisms with LIF--ciliary neurotropic factor, oncostatin M and interleukin-6--also caused expression of GFAP in these cells. These effects were inhibited by concentrations of EGF or FGF that promoted rapid cell growth.
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PMID:Regulation of glial fibrillary acidic protein in serum-free mouse embryo (SFME) cells by leukemia inhibitory factor and related peptides. 829 24

A sensitive and specific enzyme immunoassay was developed for detecting oncostatin M (OM) in human plasma and serum. The assay utilizes three anti-OM monoclonal antibodies that recognize mutually exclusive epitopes, including a neutralizing epitope. A sensitivity of 24 pg/ml was routinely obtainable. The assay showed no cross-reactivity with leukemia inhibitory factor (LIF) or interleukin-6 (IL-6), other members of the cytokine family that includes OM. The utility of the enzyme immunoassay (EIA) was demonstrated by detecting the time-dependent accumulation of OM in plasma from lipopolysaccharide (LPS)-treated human whole blood. The concentration of OM in human sera from normal donors was generally below the detection limits of the assay. However, concentrations of OM greater than 25 pg/ml were found in 17 of 212 serum samples from apparently normal donors. The detection of OM in human plasma and serum demonstrates that the EIA could be a useful tool in examining the role of OM in physiologic and pathologic states.
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PMID:Detection of oncostatin M in human plasma and serum by a sensitive enzyme immunoassay. 834 66

Leukemia inhibitory factor (LIF) is a pluripotent cytokine of importance in the regulation of immune and inflammatory responses. This cytokine may play an important role in neuronal development and bone metabolism. We have examined the ability of freshly isolated rat mast cells and mast cell lines to produce LIF at both the mRNA and bioactivity levels. Initial experiments demonstrated that two mucosal mast cell-like cell lines RBL.2H3 and RCMC9 endogenously produced low levels of LIF bioactivity. The production of this cytokine was examined using a hepatocyte-stimulating factor activity assay and confirmed by the use of neutralizing antibodies specific for LIF. This production was enhanced by treatment with the calcium ionophore A23187. No interleukin-6 production was observed by these cells either endogenously or following ionophore activation. Freshly isolated highly purified rat peritoneal mast cells also expressed mRNA for LIF. These results could have important implications for the role of mast cells in neuronal development, hematopoiesis bone metabolism and the acute-phase response.
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PMID:Leukemia inhibitory factor production by rat mast cells. 837 Mar 94

Ciliary neurotrophic factor (CNTF) and leukemia inhibitory factor (LIF) are cytokines that give rise to an identical set of tyrosine-phosphorylated proteins upon addition to responsive cells. One of these proteins is the interleukin-6 signal-transducing molecule gp130, which is required for signal transduction by both CNTF and LIF. Here we identify another prominent tyrosine-phosphorylated protein as LIF receptor (LIFR) beta, which was originally cloned as a LIF-binding protein. Cross-linking experiments with iodinated factors were carried out on a cell line responsive to CNTF and LIF, as well as on COS cells that were cotransfected with various combinations of gp130, LIFR beta, and CNTF receptor (CNTFR) alpha, the previously cloned CNTF-binding protein. These experiments reveal that LIF cross-links to LIFR beta alone, as well as to gp130 when it is coexpressed with LIFR beta. However, cross-linking of CNTF to LIFR beta and gp130 is only observed in the presence of CNTFR alpha. These and other data show that the two known LIF receptor components are recruited by CNTF and CNTFR alpha to form a trimeric CNTF receptor complex.
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PMID:Cross-linking identifies leukemia inhibitory factor-binding protein as a ciliary neurotrophic factor receptor component. 838 13

The ciliary neurotrophic factor (CNTF) receptor complex is shown here to include the CNTF binding protein (CNTFR alpha) as well as the components of the leukemia inhibitory factor (LIF) receptor, LIFR beta (the LIF binding protein) and gp130 [the signal transducer of interleukin-6 (IL-6)]. Thus, the conversion of a bipartite LIF receptor into a tripartite CNTF receptor apparently occurs by the addition of the specificity-conferring element CNTFR alpha. Both CNTF and LIF trigger the association of initially separate receptor components, which in turn results in tyrosine phosphorylation of receptor subunits. Unlike the IL-6 receptor complex in which homodimerization of gp130 appears to be critical for signal initiation, signaling by the CNTF and LIF receptor complexes depends on the heterodimerization of gp130 with LIFR beta. Ligand-induced dimerization of signal-transducing receptor components, also seen with receptor tyrosine kinases, may provide a general mechanism for the transmission of a signal across the cell membrane.
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PMID:LIFR beta and gp130 as heterodimerizing signal transducers of the tripartite CNTF receptor. 839 97

The biological functions of interleukin-6 (IL-6) are mediated through a signal-transducing component of the IL-6 receptor, gp130, which is associated with the ligand-occupied IL-6 receptor (IL-6R) protein. Binding of IL-6 to IL-6R induced disulfide-linked homodimerization of gp130. Tyrosine kinase activity was associated with dimerized but not monomeric gp130 protein. Substitution of serine for proline residues 656 and 658 in the cytoplasmic motif abolished tyrosine kinase activation and cellular responses but not homodimerization of gp130. The IL-6-induced gp130 homodimer appears to be similar in function to the heterodimer formed between the leukemia inhibitory factor (LIF) receptor (LIFR) and gp130 in response to the LIF or ciliary neurotrophic factor (CNTF). Thus, a general first step in IL-6-related cytokine signaling may be the dimerization of signal-transducing molecules and activation of associated tyrosine kinases.
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PMID:IL-6-induced homodimerization of gp130 and associated activation of a tyrosine kinase. 851 89

Human cytomegalovirus (CMV) infection is often associated with myelosuppression and acute inflammatory reaction in immunocompromised patients. We have previously documented that CMV exposure of bone marrow (BM) stromal cells reduces the capacity of these cells to support hematopoiesis because of a decreased production of colony-stimulating factors. This study examines the potential role of CMV on constitutive and lipopolysaccharide (LPS)-stimulated production of cytokines involved in inflammatory reaction, interleukin-6 (IL-6) and leukemia inhibitory factor (LIF) by BM stromal cells. The release of IL-6 was already detectable 2 hours post CMV-infection (2.5-fold increase in production) and the cumulative production of IL-6 after 5 days of infection was 23 +/- 1.2 ng/mL (ninefold increase in production). CMV was also able to induce a time-dependent production of LIF that was maximal 8 hours after CMV infection (2.5-fold increase in production). Concomitantly, there was no detectable release of granulocyte colony-stimulating factor (G-CSF) and granulocyte-macrophage CSF (GM-CSF) by CMV-infected stromal cells. The similar IL-6 and LIF production in the presence of polymyxin B ruled out the possibility that this increase could be caused by contamination of the viral stock by endotoxin. In addition, ultraviolet-inactivated virus behaved similarly to live virus and caused the release of IL-6 and LIF. However, heat-inactivated CMV was unable to induce IL-6 and LIF secretion by BM stromal cells. The production of IL-6 and LIF was also evaluated after stimulation by LPS. After 5 days of CMV exposure, the LPS-stimulated production of IL-6 and LIF was significantly lower than uninfected controls. This LPS-induced release of cytokine production was found to be dependent of viral replication. The experiments have shown that CMV is a potent inducer of IL-6 and LIF with differential effect on constitutive and LPS-stimulated cytokine production by stromal cells; we suggest that CMV induction of IL-6 and LIF during the first hours of infection could play a role in CMV-induced inflammatory reaction. Moreover, our results show that human CMV can disturb the balanced cytokine network involved in the regulation of hematopoiesis.
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PMID:Human cytomegalovirus increases constitutive production of interleukin-6 and leukemia inhibitory factor by bone marrow stromal cells. 854 77

The functional receptor complexes assembled in response to interleukin-6 and -11 (IL-6 and IL-11), leukemia inhibitory factor (LIF), oncostatin M (OSM), and ciliary neurotrophic factor (CNTF), all involve the signal transducer gp130: IL-6 and IL-11 induce homodimerization of gp130, while the rest heterodimerize gp130 with other gp130-related beta subunits. Some of these cytokines (IL-6, IL-11, and CNTF) also require a specificity-determining alpha subunit not directly involved in signaling. We have searched for functional receptor complexes for these cytokines in cells of the bone marrow stromal/osteoblastic lineage, using tyrosine phosphorylation of the beta subunits as a detection assay. Collectively, murine calvaria cells, bone marrow-derived murine cell lines (+/+LDA11 and MBA13.2), as well as murine (MC3T3-E1) and human (MG-63) osteoblast-like cell lines displayed all the previously recognized alpha and beta subunits of this family of receptors. However, individual cell types had different constellations of alpha and beta subunits. In addition and in difference to the other cell types examined, MC3T3-E1 cells expressed a heretofore unrecognized form of gp130; and MG-63 displayed an alternative form (type II) of the OSM receptor. These findings establish that stromal/osteoblastic cells are targets for the actions of all the members of the cytokine subfamily that shares the gp130 signal transducer; and suggest that different receptor repertoires may be expressed at different stages of differentiation of this lineage.
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PMID:Detection of receptors for interleukin-6, interleukin-11, leukemia inhibitory factor, oncostatin M, and ciliary neurotrophic factor in bone marrow stromal/osteoblastic cells. 856 64

Ciliary neurotrophic factor (CNTF) is a trophic protein that promotes survival and/or differentiation of a variety of neuronal cell types including sensory, sympathetic, and motor neurons. CNTF, leukemia inhibitory factor (LIF), interleukin-6 (IL-6) and oncostatin M (OSM) share a predicted common helical framework and partially identical receptor components. In this study, we present the preparation and structure--functional analysis of recombinant human CNTF. The human CNTF gene was expressed under the control of the PL promoter in Escherichia coli, and the mutants were constructed by insertion, deletion and site-directed mutagenesis. The recombinant proteins were purified from bacteria via DEAE A-50 and Sephacryl S-200 chromatography, and their survival promoting activities were determined using cultures of embryonic chick dorsal root ganglion (DRG) neurons. Insertion at position 23 with APGL, or at position 79 with PRGA, or substitution of 162L163Q for PIDG resulted in proteins with no neurotrophic activity. However, insertion at position 186 with PRGI did not alter human CNTF activity. Deletion of the carboxy-terminal amino acid 186-200 did not reduce the biological activity, but elimination of the amino acid 162-186 abolished the activity. The mutant substituting of 17 Cys for Ser was found to display a biological activity equivalent to that of the wild type. Our data provided experimental confirmation for the structural prediction of CNTF.
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PMID:Preparation and a structure-function analysis of human ciliary neurotrophic factor. 860 71

We have recently demonstrated that 50% of primitive human long-term culture-initiating cells (LTC-IC) are maintained for up to 8 weeks in stroma-dependent cultures in which progenitor-stroma contact is prevented (stroma noncontact), or when progenitors are cultured in medium conditioned by stromal feeders. This indicates that factors responsible for LTC-IC maintenance are present in soluble form in stromal supernatant (SN). Although the picogram concentrations of cytokines present in stromal SN can induce the differentiation of CD34+/HLA-DR- (DR-) cells to clonogenic cells (colony forming cells; CFC), they maintain only 10% of LTC-IC for 5 weeks, suggesting that factors other than these cytokines are required for LTC-IC maintenance. To characterize the factor(s) in stromal SN responsible for LTC-IC maintenance, we purified glycoproteins and proteoglycans (PG) from the SN of the LTC-IC supportive murine marrow stromal fibroblast cell line M2-10B4 by ion exchange high performance liquid chromatography (HPLC). Culture of DR- cells in a combination of M2-10B4-derived PG, but not glycoproteins and picogram concentrations of recombinant human interleukin-6 (IL-6), granulocyte colony-stimulating factor (G-CSF), stem cell factor (SCF), leukemia inhibitory factor (LIF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and macrophage inflammatory protein-1alpha (MIP-1alpha) resulted in the recovery of 96% +/- 8% of LTC-IC maintained in cultures supplemented with unfractionated stromal SN. LTC-IC maintenance was largely retained after digestion of the PG-rich fraction with proteinase K and after dissociative gel filtration chromatography, but was completely abolished following treatment with nitrous acid, which digests heparan sulfate glycosaminoglycans (HS GAG). As for M2-10B4-derived HS GAG, high concentrations of bovine kidney HS GAG, but not bovine tracheal chondroitin sulfate, significantly improved cytokine-mediated LTC-IC maintenance. Maintenance of LTC-IC by these nonmarrow-derived HS GAG was, however, significantly lower than that seen with M2-10B4-derived HS. These studies demonstrate a role for marrow stroma-derived HS GAG in the long-term in vitro maintenance of human LTC-IC. Further structure-function analysis of these HS GAG may have important implications for ex vivo stem cell expansion and gene transfer into hematopoietic progenitors.
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PMID:Stromal fibroblast heparan sulfate is required for cytokine-mediated ex vivo maintenance of human long-term culture-initiating cells. 860 38


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