Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

Stimulation of hemopoietic cells with IL-3, IL-4, IL-5, granulocyte-macrophage-CSF and Steel factor-(SLF) induced tyrosine phosphorylation of a number of protein substrates. Two of these proteins, designated p42 and p44, were tyrosine phosphorylated rapidly in response to treatment with IL-3, IL-5, granulocyte-macrophage-CSF and SLF, but not IL-4. We demonstrate that these common substrates are members of the mitogen-activated protein kinase (MAP kinase) family of protein serine/threonine kinases. Ion-exchange chromatography yielded a peak of MAP kinase activity eluting at 0.3 to 0.32 M NaCl. Immunoblotting of column fractions with antiphosphotyrosine antibodies showed coelution of the peak of MAP kinase enzyme activity with the p42 and p44 tyrosine phosphorylated species, and with two proteins of 42 and 44 kDa which were immunoreactive with anti-MAP kinase antibodies. Moreover, a characteristic shift in mobility of the p42 and p44 species was observed after factor treatment. Time-course analyses and subsequent ion-exchange chromatography demonstrated SLF activation of MAP kinase activity was maximal after 2 min of factor treatment and decreased to basal levels after 30 min stimulation. By contrast, activation of MAP kinase after IL-5 treatment was not as rapid. Maximal activity was observed 15 min after stimulation and remained elevated for up to 60 min after IL-5 addition. Investigation of the role of protein kinase C in the mechanism of activation by these growth factors demonstrated that specific inhibition of protein kinase C led to a reduction, but not ablation, of the SLF and IL-3 induced stimulation of MAP kinase activity. The use of synthetic peptide substrates confirmed SLF and IL-5 activate isoforms of MAP kinases. These results demonstrate that members of the MAP kinase family are involved in common signal transduction events elicited by IL-3, IL-5, granulocyte-macrophage-CSF and Steel factor, but not those involving IL-4.
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PMID:Multiple hemopoietic growth factors stimulate activation of mitogen-activated protein kinase family members. 138 May 36

Apoptosis of haemopoietic cells can be inhibited by various cytokines, but the specific signalling pathways involved are not well defined. Interleukin (IL)-4 has unique actions since it is unable to activate p21ras or mitogen-activated protein kinase, but can activate PtdIns 3-OH-kinase (PtdIns 3-kinase), the latter effect being shared with most other cytokines. In many cases, IL-4 is able to maintain cell viability by inhibiting apoptosis, but is unable to stimulate continuous proliferation of cells. This led us to investigate the role of PtdIns 3-kinase in inhibition of apoptosis. Two potent inhibitors of PtdIns 3-kinase, wortmannin and LY294002, rapidly induced apoptosis in cells incubated in the presence of IL-4, at concentrations consistent with their ability to inhibit PtdIns 3-kinase activity in whole cells. Interestingly, the same effect was seen in cells in the presence of IL-3 and Steel factor, while cells incubated in the presence of granulocyte-macrophage colony stimulating factor, and to a lesser extent, IL-5 could bypass the effect of wortmannin or LY294002. Therefore, this study suggests that PtdIns 3-kinase activity provides an important, although not a unique signal, required to inhibit apoptosis in haemopoietic cells.
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PMID:Role of phosphatidylinositol 3-OH-kinase activity in the inhibition of apoptosis in haemopoietic cells: phosphatidylinositol 3-OH-kinase inhibitors reveal a difference in signalling between interleukin-3 and granulocyte-macrophage colony stimulating factor. 749 6

Insulin receptor substrate 1 (IRS-1) mediates the activation of a variety of signaling pathways by the insulin and insulin-like growth factor 1 receptors by serving as a docking protein for signaling molecules with SH2 domains. We and others have shown that in response to insulin stimulation IRS-1 binds GRB2/Sos and have proposed that this interaction is important in mediating Ras activation by the insulin receptor. Recently, it has been shown that the interleukin (IL)-4 receptor also phosphorylates IRS-1 and an IRS-1-related molecule, 4PS. Unlike insulin, however, IL-4 fails to activate Ras, extracellular signal-regulated kinases (ERKs), or mitogen-activated protein kinases. We have reconstituted the IL-4 receptor into an insulin-responsive L6 myoblast cell line and have shown that IRS-1 is tyrosine phosphorylated to similar degrees in response to insulin and IL-4 stimulation in this cell line. In agreement with previous findings, IL-4 failed to activate the ERKs in this cell line or to stimulate DNA synthesis, whereas the same responses were activated by insulin. Surprisingly, IL-4's failure to activate ERKs was not due to a failure to stimulate the association of tyrosine-phosphorylated IRS-1 with GRB2/Sos; the amounts of GRB2/Sos associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. Moreover, the amounts of phosphatidylinositol 3-kinase activity associated with IRS-1 were similar in insulin- and IL-4-stimulated cells. In contrast to insulin, however, IL-4 failed to induce tyrosine phosphorylation of Shc or association of Shc with GRB2. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Thus, ERK activation correlates with Shc tyrosine phosphorylation and formation of an Shc/GRB2 complex. Previous studies have indicated that activation of ERks in this cell line is dependent upon Ras since a dominant-negative Ras (Asn-17) blocks ERK activation by insulin. Our findings, taken in the context of previous work, suggest that binding of GRB2/Sos to Shc may be the predominant mechanism whereby insulin as well as cytokine receptors activate Ras.
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PMID:Association between GRB2/Sos and insulin receptor substrate 1 is not sufficient for activation of extracellular signal-regulated kinases by interleukin-4: implications for Ras activation by insulin. 786 67

Insulin Receptor Substrate-1 (IRS-1) is an endogenous cellular protein that is tyrosine phosphorylated during stimulation of cells with insulin, IGF-1, and interleukin 4 (IL-4). Phosphorylated IRS-1 regulates multiple regulatory pathways by recruiting signaling molecules containing Src homology 2 domains (SH2 proteins). The 32D myeloid progenitor cell line contains few insulin receptors and no detectable IRS-1. Expression of the insulin receptor alone partially mediates insulin-stimulated microtubule-associated protein (MAP) kinase activation, and the addition of IRS-1 enhances this effect (Myers, M. G., Jr., Wang, L.-M., Sun, X. J., Zhang, Y., Yenush, L. P., Schlessinger, J., Pierce, J. H., and White, M. F. (1994) Mol. Cell. Biol. 14, 3577-3587). Alone, insulin receptors mediate phosphatidylinositol (PI) 3'-kinase and p70S6k activation poorly if at all during insulin stimulation. Expression of IRS-1 alone in 32D cells mediates the stimulation of p70S6k by insulin, IGF-1, or IL-4; addition of insulin receptor to these cells increases the sensitivity of the insulin response. In contrast, full insulin stimulation of PI 3'-kinase requires both the insulin receptor and IRS-1, suggesting that a high level of IRS-1 phosphorylation is required for insulin-stimulated PI 3'-kinase activation, whereas a low level of IRS-1 tyrosine phosphorylation transmits an essential signal to p70S6k. Both insulin receptors and IRS-1 are required for mitogenic signaling in 32D cells suggesting that MAP kinase or p70S6k alone are not sufficient, and that both or additional unknown IRS-1-mediated signals are necessary.
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PMID:Insulin receptor substrate-1 mediates phosphatidylinositol 3'-kinase and p70S6k signaling during insulin, insulin-like growth factor-1, and interleukin-4 stimulation. 796 33

IRS-1 has been found to relay the signals from the receptors for insulin, insulin-like growth factor-1, growth hormone, and many cytokines for the downstream effects in the various cell types tested. For interleukin 4 signaling, most studies were performed on hematopoietic cells and cell lines transfected with rat liver IRS-1 cDNA. In a liver cell lineage, IRS-1 expression has been found to be increased in hepatoma cells and hepatocytes in regenerating liver. To elucidate the possible function and the signal transduction pathway for interleukin 4, in comparison with insulin, in liver cells, we used the Hep 3B hepatoma cell line as a model system. Following insulin and interleukin 4 stimulation, rapid tyrosyl phosphorylation of IRS-1 occurred. Interleukin 4, but not insulin, stimulated the tyrosine phosphorylation of JAK1 and, to a lesser extent, JAK2. In contrast to the other cell types, the association of IRS-1 and Grb2 through the SH2 of Grb2 was demonstrated after IL-4 and insulin stimulation of the Hep3B hepatoma cells. Both insulin and interleukin 4 stimulated tyrosine phosphorylation and the enzyme activity of Erk1 kinase. Our results indicate that interleukin 4 and insulin might modulate hepatic cell growth and differentiation through many different or common pathways for the activation of JAK kinases and the usage of IRS-1 as a docking protein. The binding of IRS-1 with Grb2 after IL-4 as well as insulin stimulation may lead to MAP kinase activation, probably through the Grb2/sos/p21ras pathway.
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PMID:Signal transduction pathways for interleukin 4 and insulin in human hepatoma cells. 886 52

Stimulation of T cells via the T cell receptor (TCR) activates a number of signaling pathways that are potentially involved in the elicitation of physiological responses, such as the production of cytokines. The extracellular signal-regulated kinases (ERK) are a group of molecules activated in response to TCR ligation, whose role in T cell cytokine production is controversial. In this study, we have asked whether ERK activation is coupled to the production of a number of T cell-derived cytokines, and whether particular cytokines are differentially affected by ERK activation. To address these questions, we have utilized a constitutively active version of the immediate upstream activator of both ERK1 and ERK2, mitogen-activated/extracellular signal-regulated kinase 1 (MEK1), to activate ERK signaling selectively in the absence of other TCR-activated signaling pathways. The effect of constitutive MEK/ERK activation on T cell cytokine production was measured by transiently co-transfecting newly activated mouse T cells with DNA encoding constitutively active MEK1 (CA-MEK1) and the human interleukin-2 (IL-2) receptor alpha chain (hCD25), purifying hCD25+ transfectants by flow-cytometric cell sorting, and measuring the production of IL-3, IL-4, interferon (IFN)-gamma and granulocyte/macrophage-colony-stimulating factor (GM-CSF) either in the presence or absence of ionomycin stimulation. Newly activated T cells were used in these experiments as they more closely resemble T cells activated in vivo than do transformed T cells or long-term established T cell clones. CA-MEK1 expression led to constitutive ERK activation, which acted synergystically with ionomycin treatment to stimulate cytokine production. Furthermore, these experiments revealed a hierarchy of cytokine responsiveness to MEK/ERK activation, such that the production of IL-3 was most affected, followed by GM-CSF, IFN-gamma, and IL-4.
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PMID:Differential activation of T cell cytokine production by the extracellular signal-regulated kinase (ERK) signaling pathway. 889 34

The stress-activated protein/c-Jun N-terminal kinases (SAPK/JNK) have been shown to be activated by pro-inflammatory cytokines, as well as physical and chemical stresses. We now show that a variety of hematopoietic growth factors, including Steel locus factor (SLF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukin-3 (IL-3), all of which promote the growth and survival of various lineages of hematopoietic cells, activate the stress-activated protein kinases in the factor-dependent cell line MC/9. These hematopoietic growth factors activated both 46- and 55-kD isoforms of both SAPK gamma and SAPK alpha. Furthermore, we demonstrate that SAPK activation correlated with the phosphorylation of SAPK/ERK kinase-1 (SEK1) after treatment with SLF or GM-CSF. Interestingly, IL-4, a cytokine with distinctive and important effects on the immune system, was the exception among the hematopoietic growth factors we examined in failing to induce activation of SAPK gamma, SAPK alpha, or SEK1. These findings show that activation of SAPK is involved, not only in responses to stresses, but also in signaling by growth factors that regulate the normal development and function of cells of the immune system.
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PMID:Activation of the stress-activated protein kinases by multiple hematopoietic growth factors with the exception of interleukin-4. 912 10

We previously showed that T cells from the mediastinal lymph nodes (MLN) and lung parenchyma of influenza virus-infected mice were functionally remarkably different. Here we demonstrate that the differences in cytokine production are due to differences in the frequencies of T cells within the activated pool able to produce cytokines after TCR stimulation. FACS analysis of T cells from MLN and lung tissue demonstrated that T cells expressing any of the activation markers tested (LFA-1, CD25, CD44, CD45RB, CD49d, CD62L) always expressed high levels of CD44 and LFA-1. These double-high T cells produced >99% of all anti-CD3 mAb-induced IL-4 and IFN-gamma. Separation of T cells employing mAb against the other activation markers in combination with anti-CD44 mAb did not enable further fractionation into cytokine producers and nonproducers. Despite their similar phenotype, purified double-high lung parenchyma T cells produced markedly higher levels of IL-2, IL-4, and IFN-gamma, and contained a higher frequency of cytokine producers than their MLN counterparts. Activation of the extracellular signal-regulated kinase (ERK)-2 in response to TCR cross-linking was detected in double-high T cells from lung tissue but not MLN. The requirement for ERK signaling for maximal IFN-gamma synthesis could nevertheless be demonstrated in both populations by blockade with the inhibitor PD98509. Collectively, the data suggest that inductive and effector sites differ in the frequency of activated T cells able to induce ERK-2-regulated cytokine production after TCR ligation.
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PMID:Activated T cells from draining lymph nodes and an effector site differ in their responses to TCR stimulation. 923 12

The dual specific kinase SAPK/ERK1 kinase (SEK1; mitogen-activated protein kinase kinase 4/Jun NH2 terminal kinase [ JNK] kinase) is a direct activator of stress-activated protein kinases ([SAPKs]/JNKs) in response to CD28 costimulation, CD40 signaling, or activation of the germinal center kinase. Here we show that SEK1(-/-) recombination-activating gene (RAG)2(-/-) chimeric mice have a partial block in B cell maturation. However, peripheral B cells displayed normal responses to IL-4, IgM, and CD40 cross-linking. SEK1(-/-) peripheral T cells showed decreased proliferation and IL-2 production after CD28 costimulation and PMA/Ca2+ ionophore activation. Although CD28 expression was absolutely crucial to generate vesicular stomatitis virus (VSV)-specific germinal centers, SEK1(-/-)RAG2(-/-) chimeras mounted a protective antiviral B cell response, exhibited normal IgG class switching, and made germinal centers in response to VSV. Interestingly, PMA/Ca2+ ionophore stimulation, which mimics TCR-CD3 and CD28-mediated signal transduction, induced SAPK/JNK activation in peripheral T cells, but not in thymocytes, from SEK1(-/-) mice. These results show that signaling pathways for SAPK activation are developmentally regulated in T cells. Although SEK1(-/-) thymocytes failed to induce SAPK/JNK in response to PMA/Ca2+ ionophore, SEK1(-/-)RAG2(-/-) thymocytes proliferated and made IL-2 after PMA/Ca2+ ionophore and CD3/CD28 stimulation, albeit at significantly lower levels compared to SEK1(+/+)RAG2(-/-) thymocytes, implying that CD28 costimulation and PMA/Ca2+ ionophore-triggered signaling pathways exist that can mediate proliferation and IL-2 production independently of SAPK activation. Our data provide the first genetic evidence that SEK1 is an important effector molecule that relays CD28 signaling to IL-2 production and T cell proliferation.
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PMID:Impaired CD28-mediated interleukin 2 production and proliferation in stress kinase SAPK/ERK1 kinase (SEK1)/mitogen-activated protein kinase kinase 4 (MKK4)-deficient T lymphocytes. 929 48

Activation and recruitment of eosinophils in allergic inflammation is in part mediated by chemoattractants and T-helper 2 (Th2)-derived cytokines. However, little is known concerning the signal transduction mechanisms by which this activation occurs. We have investigated tyrosine kinase-mediated activation of phosphatidylinositol 3-kinase (PI3K) and compared this with the activation of the p21ras-ERK signaling pathway in human eosinophils. The related cytokines interleukin-3 (IL-3), IL-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF), all induced PI3K activity detected in antiphosphotyrosine immunoprecipitates. Furthermore, the chemoattractants platelet-activating factor (PAF), RANTES, and C5a were also able to induce phosphotyrosine-associated PI3K activity. Protein kinase B (PKB) is a downstream target of PI3K activation by growth factors. Induction of PKB phosphorylation in human eosinophils was transiently induced on activation with the cytokines IL-4 and IL-5, as well as the chemoattractants PAF, C5a, and RANTES showing a broad activation profile. Surprisingly, analysis of the activation of the mitogen-activated protein (MAP) kinases p44(ERK1) and p42(ERK2), showed that ERK2, but not ERK1, was transiently activated in human eosinophils after stimulation with IL-5 or PAF. Activation kinetics correlated with activation of p21ras by both cytokines and chemoattractants as measured by a novel assay for guanosine triphosphate (GTP)-loading. Finally, using specific inhibitors of both the p21ras-ERK and PI3K signaling pathways, a role was demonstrated for PI3K, but not p21ras-ERK, in activation of the serum-treated zymosan (STZ)-mediated respiratory burst in IL-5 and PAF-primed eosinophils. In summary, these data show that in human eosinophils, Th2-derived cytokines differentially activate both PI3K and MAP kinase signal transduction pathways with distinct functional consequences showing complex regulation of eosinophil effector functions.
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PMID:Analysis of signal transduction pathways in human eosinophils activated by chemoattractants and the T-helper 2-derived cytokines interleukin-4 and interleukin-5. 951 56


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