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Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ciliary neurotrophic factor (CNTF), leukemia inhibitory factor (LIF), oncostatin M (OSM), and interleukin-6 (IL6) compose a family of distantly related cytokines that initiate signaling by inducing either homodimerization of the "beta" signal transducing receptor component gp130 (in the case of IL6) or heterodimerization between gp130 and the gp130-related LIFR beta (in the case of CNTF, LIF, and OSM); dimerization of beta receptor components in turn activates members of the Jak/Tyk family of receptor-associated tyrosine kinases. Here we report that CNTF, LIF, OSM, and IL6 induce most of the same protein tyrosine phosphorylations, regardless of the cell type assayed or whether they initiate signaling by inducing homo- or heterodimerization of beta components. Although several of the protein tyrosine phosphorylations induced by the CNTF/LIF/OSM/IL6 family of factors may correspond to novel tyrosine kinase targets, we have been able to demonstrate the involvement of known signaling molecules, such as phospholipase C gamma, phosphoinositol 3-kinase, phosphotyrosine phosphatase (PTP1D), pp120, SHC, GRB2, STAT91, Raf-1, and the mitogen-activated protein kinases ERK1 and ERK2, revealing substantial convergence not only between the pathways activated by this cytokine family and other cytokines, but with pathways previously known to be activated only by factors that utilize receptor tyrosine kinases. Our data suggest the beta receptor components can form complexes with some of the signaling proteins identified and may play some role in their recruitment.
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PMID:Ciliary neurotrophic factor/leukemia inhibitory factor/interleukin 6/oncostatin M family of cytokines induces tyrosine phosphorylation of a common set of proteins overlapping those induced by other cytokines and growth factors. 751 71

IL-11 is a multifunctional cytokine biologically related to IL-6, leukemia inhibitory factor (LIF), oncostatin M (OSM) and ciliary neurotrophic factor (CNTF). It has been shown that these cytokines can utilize common signal transducer, gp130. We have demonstrated that Jak tyrosine kinases, MAP kinases and pp90rsk are highly activated by IL-11 and related cytokines. In addition, we have identified pp90rsk as one of the H7 sensitive protein kinases critical for primary response gene expression induced by IL-11. Furthermore, activation of 3CH134 (a MAP kinase phosphatase) gene by IL-11 suggested that a MAP kinase phosphatase may be involved in IL-11-mediated signal transduction. Our data also suggested that tyrosine phosphorylation of Stat91 and related transcriptional factors is involved in IL-11 signaling but is not sufficient for the activation of primary response genes such as JunB, tis11, tis8 and MAP kinase phosphatase in mouse preadipocytes. The understanding of signal transduction pathways mediated by IL-11 and related cytokines may help to define the common and unique biological properties of these growth factors.
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PMID:Interleukin (IL)-11--mediated signal transduction. 754 69

Oncostatin-M (OSM) is a potent mitogen for Kaposi's sarcoma (KS) cells. We studied signaling by the OSM receptor in three AIDS-related KS lines and show induction of tyrosine phosphorylation of 145-, 120-, 85-, and 42-kD substrates. The 42-kD substrate was identified as p42MAPK (mitogen-activated protein kinase), also known as ERK-2. This serine/threonine kinase relays mitogenic signals from receptor tyrosine protein kinases (TPKs) or receptor-associated TPKs to transcriptional activators. The OSM dose dependence for MAP kinase activation and induction of KS cell growth were almost identical, suggesting functional linkage. MAP kinase activation was dependent on tyrosine phosphorylation, and both OSM-induced MAP kinase activity and KS cell growth could be suppressed by TPK inhibitors, genistein and geldanomycin. OSM also stimulated tyrosine phosphorylation of similar substrates and MAP kinase activity in human vein endothelial cells. While it has been proposed that the OSM receptor may include the gp130 subunit of the IL-6 receptor and alpha-chain of leukemia inhibitory factor (LIF) receptor, neither LIF nor r.IL-6 induced tyrosine protein phosphorylation or p42MAPK activation in KS cells. However, r.IL-6 did stimulate tyrosine phosphorylation and p42MAPK activity in the human B cell line, AF-10, while OSM and LIF exerted no effects. Our results indicate that, although the OSM and IL-6 receptors share a common signaling pathway, this pathway is selectively activated by OSM in Kaposi's cells.
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PMID:Oncostatin-M stimulates tyrosine protein phosphorylation in parallel with the activation of p42MAPK/ERK-2 in Kaposi's cells. Evidence that this pathway is important in Kaposi cell growth. 768 64

We have previously shown that the IL-6R in a growth-responsive B cell line, AF10, induces activation of mitogen-activated protein (MAP) kinase. Here we demonstrate the activation of Raf-1 and MEK-1, which act as a MAP kinase kinase kinase and a MAP kinase kinase, respectively, in the MAP kinase cascade induced by IL-6 in AF10 cells. IL-6 also induced tyrosine phosphorylation of the signaling transducing subunit of the IL-6R in AF10 cells, along with tyrosine phosphorylation of the gp130-associated tyrosine protein kinase JAK1 and the adaptor molecule p52shc. Although induction of tyrosine phosphorylation and activation of MAP kinase by IL-6 in a differentiation-responsive B cell line, SKW 6.4, were below the limits of detection, the phorbol ester PMA did activate Raf-1, MEK-1, and MAP kinase without inducing the phosphorylation of gp130, JAKs, or p52shc. These results suggest that JAK kinase family members associated with the IL-6R may participate in the activation of MAP kinase in AF10 cells by way of an adaptor protein and Ras-dependent kinase cascade.
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PMID:Involvement of Janus kinases, p52shc, Raf-1, and MEK-1 in the IL-6-induced mitogen-activated protein kinase cascade of a growth-responsive B cell line. 796 20

Interleukin-11 is a stromal derived cytokine important in hematopoiesis. IL-11 intracellular signaling travels through cytoplasmic kinases of the Janus family. How JAKs accomplish the multiple functions of IL-11 has not been determined and until recently only a few associated downstream proteins have been identified. We present evidence here for the IL-11 induced association of PP2A, P13K, and Yes to JAK2. Reciprocal immunoprecipitations support the mutual involvement of these signaling components in IL-11 mediated signal transduction. This novel finding of JAK2/PP2A binding and release may have relevance to many serine/threonine regulated mechanisms such as P13K, Stat, and MAPK activation. These associations support a model of JAK2 as a protein kinase docking protein of IL-11 signal transduction that may be applicable to other gp130 and JAK signal transduction systems.
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PMID:Complex formation of JAK2 with PP2A, P13K, and Yes in response to the hematopoietic cytokine interleukin-11. 870 85

gp130 is a common signal transducer for the interleukin-6-related cytokines. To delineate the gp130-mediated growth signal, we established a series of pro-B cell lines expressing chimeric receptors composed of the extracellular domain of the granulocyte colony-stimulating factor receptor and the transmembrane and cytoplasmic domains of gp130. The second tyrosine (from the membrane) of gp130, which was required for the tyrosine phosphorylation of SHP-2, its association with GRB2, and activation of a MAP kinase, was essential for mitogenesis, but not for anti-apoptosis. On the other hand, the tyrosine in the YXXQ motifs essential for STAT3 activation was required for bcl-2 induction and anti-apoptosis. Furthermore, dominant-negative STAT3 inhibited anti-apoptosis. These data demonstrate that two distinct signals, mitogenesis and anti-apoptosis, are required for gp130-induced cell growth and that STAT3 is involved in anti-apoptosis.
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PMID:Two signals are necessary for cell proliferation induced by a cytokine receptor gp130: involvement of STAT3 in anti-apoptosis. 893 72

The leukemia inhibitory factor/interleukin 6 (LIF/IL6) family of cytokines promotes cell type-specific pleiotropic effects by engaging multimeric receptor complexes that share the common affinity converter/signal transducing subunit gp130. While the maintenance of embryonic stem (ES) cell self-renewal is an activity unique to this family of cytokines, the intracellular signaling events mediated by gp130 remain largely unknown. Here we show a rapid and transient increase in the specific activity of the Src-related kinase Hck as well as of the Janus kinases Jak1, Jak2, and Tyk2 following treatment of ES cells with LIF or a combination of IL6 plus a soluble form of the IL6 receptor. Within 2 min of stimulation, we also observed increased tyrosine phosphorylation of SHC, activation of the guanidine nucleotide exchange activity on p21(ras), and an electrophoretic mobility shift of MAP kinase. Functional involvement of Hck and p21(ras) activation in gp130-mediated signaling is supported by the finding that the introduction of constitutively activated Hck or v-Ha-ras partially alleviates the requirement of ES cells for LIF to remain undifferentiated. In contrast, suppression of Jak1 in ES cells by antisense technology increased the amount of LIF required to retain their pluripotentiality. These results are consistent with the notion that gp130-mediated suppression of ES cell differentiation depends on signaling through at least two cascades, namely a p21(ras)-dependent pathway that possibly involves Hck, as well as a Jak kinase-dependent pathway.
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PMID:Gp130-mediated signal transduction in embryonic stem cells involves activation of Jak and Ras/mitogen-activated protein kinase pathways. 893 63

Type I interferons (IFNs-alpha and IFN-beta) bind to a common receptor to exert strong antiproliferative activity on a broad range of cell types, including interleukin-6 (IL-6)-dependent myeloma cells. In this study, we investigated the effect of IFN-beta pretreatment on IL-6-stimulated mitogenic signaling in the human myeloma cell line U266. IL-6 induced transient tyrosine phosphorylation of the IL-6-receptor signal-transducing subunit gp130, the gp130-associated protein tyrosine kinases Jak1,Jak2, and Tyk2, the phosphotyrosine phosphatase PTP1D/Syp, the adaptor protein Shc and the mitogen-activated protein kinase Erk2, and accumulation of GTP-bound p21ras. Prior treatment of U266 cells with IFN-beta downregulated IL-6-induced tyrosine phosphorylation of gp130, Jak2, PTP1D/Syp, Shc, and Erk2, and GTP-loading of p21ras. Further analysis indicated that treatment with IFN-beta disrupted IL-6-induced binding of PTP1D/Syp to gp130 and the adaptor protein Grb2; IFN-beta pretreatment also interfered with IL-6-induced interaction of Shc with Grb2 and a 145-kD tyrosine-phosphorylated protein. These results suggest a novel mechanism whereby type I IFNs interrupt IL-6-promoted mitogenesis of myeloma cells in part by preventing the formation of essential signaling complexes leading to p21ras activation.
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PMID:Interferon-beta interrupts interleukin-6-dependent signaling events in myeloma cells. 897

IL-6 is a multifunctional cytokine involved in hemopoiesis, immune regulation, inflammation, neural development, and infection. IL-6 belongs to a family of related cytokines that includes leukemia inhibitory factor, oncostatin M, IL-11, ciliary neurotropic factor, and cardiotropin-1, all of which initiate signaling through a receptor-associated gp130. IL-6 induces homodimerization of gp130 and activates the Jak/STAT pathway of signal transduction. In addition, IL-6 stimulates the mitogen-activated protein kinases designated ERK (extracellular signal-regulated kinase)-1 and -2. Activation of ERK-1 and -2 may involve the Src homology-2 containing proteins Shc and Grb2. Here we provide evidence that Shc could function as signaling molecules for IL-6 in DeFew-IL-6R/gp130 cells, a human B lymphoma cell line engineered to express high levels of both the IL-6R (p80) and the gp130 subunit. IL-6 was shown to promote the rapid tyrosine phosphorylation of gp130, Jak2, and Shc proteins. Moreover, Shc associated both in vivo and in vitro with phosphorylated gp130 through the Shc-Src homology-2 domain. We also report that Shc bound to activated Jak2 by using the Shc amino terminal phosphotyrosine interaction domain. Following IL-6 stimulation, Shc physically associated with Grb2. Thus, the data point to Shc proteins as a functional link between the Jak2 and Ras pathways of IL-6 signal transduction.
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PMID:Shc mediates IL-6 signaling by interacting with gp130 and Jak2 kinase. 912 68

Chimeric receptors containing the entire or various cytoplasmic domains of either gp130 or leukemia inhibitory factor receptor alpha (LIFR) were used to identify signaling molecules and regions of these polypeptides required for the stimulation of mitogen-activated protein kinase (MAPK). Coexpression of dominant-negative Jak2 inhibited chimeric receptor-stimulated MAPK activity by approximately 70%, while expression of dominant-negative Ras completely blocked MAPK activation by either receptor polypeptide. Deletion analysis identified a 24-amino acid region of gp130 that was necessary for maximal stimulation of MAPK, and contained box 3 (positions 120-129) and a consensus tyrosine binding motif (Tyr-118) for the protein-tyrosine phosphatase, SHP2. Expression of receptors lacking this region or of chimeric gp130(Y118F) point mutants inhibited MAPK activity by approximately 55%, suggesting that Tyr-118, but not box 3, was required during activation of MAPK by gp130. Similarly, expression of chimeric LIFR constructs lacking box 3 maximally stimulated MAPK activity, while those lacking Tyr-115, a putative SHP2 binding site, inhibited stimulation of MAPK by this polypeptide. Our results demonstrate that gp130 and LIFR stimulate MAPK activity through box 3-independent mechanisms involving: (i) effects at Tyr-118 and Tyr-115, respectively, for maximal stimulation of MAPK activity and (ii) a Jak/Tyk-dependent pathway that, together with Tyr-118- or Tyr-115-generated signals, converges at the level of Ras during activation of MAPK by cytokine.
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PMID:Box 3-independent signaling mechanisms are involved in leukemia inhibitory factor receptor alpha- and gp130-mediated stimulation of mitogen-activated protein kinase. Evidence for participation of multiple signaling pathways which converge at Ras. 919 77


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