Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.24 (mitogen-activated protein kinase)
 95,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Internal tandem duplication (ITD) in the juxtamembrane portion of Fms-like tyrosine kinase 3 (FLT3), a type III receptor tyrosine kinase (RTK), is the most common molecular defect associated with acute myeloid leukemia (AML). The high prevalence of this activating mutation makes it a potential target for molecularly based therapy. Indolinone tyrosine kinase inhibitors have known activity against KIT, another member of the type III RTK family. Given the conserved homology between members of this family, we postulated that the activity of some KIT inhibitors would extend to FLT3. We used various leukemic cell lines (BaF3, MV 4-11, RS 4;11) to test the activity of indolinone compounds against the FLT3 kinase activity of both wild-type (WT) and ITD isoforms. Both SU5416 and SU5614 were capable of inhibiting autophosphorylation of ITD and WT FLT3 (SU5416 concentration that inhibits 50% [IC(50)], 100 nM; and SU5614 IC(50) 10 nM). FLT3-dependent activation of the downstream signaling proteins mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 5 (STAT5) was also inhibited by treatment in the same concentration ranges. FLT3 inhibition by SU5416 and SU5614 resulted in reduced proliferation (IC(50), 250 nM and 100 nM, respectively) and induction of apoptosis of FLT3 ITD-positive leukemic cell lines. Treatment of these cells with an alternative growth factor (granulocyte-macrophage colony-stimulating factor [GM-CSF]) restored MAPK signaling and cellular proliferation, demonstrating specificity of the observed inhibitory effects. We conclude that SU5416 and SU5614 are potent inhibitors of FLT3. Our finding that inhibition of FLT3 induces apoptosis of leukemic cells supports the feasibility of targeting FLT3 as a novel treatment strategy for AML.
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PMID:SU5416 and SU5614 inhibit kinase activity of wild-type and mutant FLT3 receptor tyrosine kinase. 1235 6

Environmental pollutants, including ambient particulate matter (PM), increase respiratory morbidity. Studies of model PM particles, including residual oil fly ash and freshly generated diesel exhaust particles, have demonstrated that PM affects inflammatory airway responses. Neither of these particles completely represents ambient PM, and therefore questions remain about ambient particulates. We hypothesized that ambient PM of different size fractions collected from an urban environment (New York City air), would activate primary culture human bronchial epithelial cells (HBECs). Because of the importance of granulocyte-macrophage colony-stimulating factor (GM-CSF) on inflammatory and immunomodulatory processes, we focused our studies on this cytokine. We demonstrated that the smallest size fraction (ultrafine/fine; < 0.18 micro m) of ambient PM (11 micro g/cm(2)), upregulated GM-CSF production (2-fold increase). The absence of effect of carbon particles of similar size, and the day-to-day variation in response, suggested that the chemical composition, but not the particle itself, was necessary for GM-CSF induction. Activation of the extracellular signal-regulated kinase and the p38 mitogen-activated protein kinase was associated with, and necessary for, GM-CSF release. These studies serve to corroborate and extend those on model particles. Moreover, they emphasize the role of the smallest size ambient particles in airway epithelial cell responses.
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PMID:Size fractions of ambient particulate matter induce granulocyte macrophage colony-stimulating factor in human bronchial epithelial cells by mitogen-activated protein kinase pathways. 1235 79

Interleukin-3 (IL-3)-induced activation of endogenous Rac-1, Rac-2, and Cdc42. Rac-1 was also activated by colony-stimulating factor-1 (CSF-1), Steel locus factor (SLF), granulocyte-macrophage colony-stimulating factor (GM-CSF), and IL-5 or by cross-linking the B-lymphocyte receptor for antigen (BCR). The activation of Rac-1 induced by cross-linking the BCR or by IL-3 stimulation was blocked only partially by Ly294002, with about 25% to 30% of Rac-1 activation still occurring in the absence of detectable increases in phosphatidyl-inositol-3 kinase (PI-3K) activity. Overexpression of constitutively active mutants of H-Ras, N-Ras, or M-Ras resulted in activation of coexpressed Rac-1 through an Ly29402-resistant, PI-3K-independent mechanism. Overexpression of constitutively active mutants of p21 Ras, or Rac-1, but not of PI-3K, was sufficient for activation of p38 mitogen-activated protein kinase (MAPK) in cells of hemopoietic origin. Inhibition of increases in PI-3K activity by Ly294002 had no effect on the IL-3-induced activation of p38 MAPK. In contrast, Ly294002 partially inhibited the activation of p38 MAPK induced by cross-linking of the BCR, although some p38 MAPK activation occurred in the absence of increases in the activity of Rac-1 or PI-3K. The activation of Rac-1, Rac-2, and Cdc42 by IL-3 and other hemopoietic growth factors is likely to be an important component of their actions in promoting growth, survival, and function.
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PMID:Activation of Rac-1, Rac-2, and Cdc42 by hemopoietic growth factors or cross-linking of the B-lymphocyte receptor for antigen. 1238 16

Human immunodeficiency virus type-1 (HIV-1) gene expression is known to be affected by numerous cytokines or growth factors. However, the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) on long terminal repeat (LTR)-mediated transcription of HIV-1 still remains unknown. By transient transfection experiments with HIV-1 LTR reporter constructs, we showed that strong LTR-mediated activation was induced by GM-CSF in mouse Ba/F3 cells expressing human GM-CSF receptors (GM-CSFR). Mutational analysis of the HIV-1 LTR reporters revealed that both NF-kappaB and Sp1 binding sites play important roles as positive regulatory elements. Analysis of various mutants of the cytoplasmic region of GM-CSFR indicated that both the conserved membrane proximal region and tyrosine residues located in the distal part of the beta subunit were required for HIV-1 LTR activation. Possible involvement of MAPK and PI3-K signalling pathways was suggested by the partial inhibition by wortmannin, a specific inhibitor of the PI3-K pathway, and enhancement by constitutively active MEK1, of HIV-1 LTR activation. However, the MEK1 pathway is not essential since MEK1 inhibitor PD98059 did not suppress GM-CSF-induced HIV-1-LTR activation. Further analyses of GM-CSFR mutants suggested that some other unknown signalling pathway also participates in GM-CSF-induced HIV-1 LTR activation. Taken together, the data suggest that GM-CSF could upregulate the LTR-driven transcription of HIV-1 through modulation of NF-kappaB and SP1 by multiple signalling pathways.
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PMID:Human GM-CSF induces HIV-1 LTR by multiple signalling pathways. 1245 35

We investigated the intracellular signaling mechanisms for cytokine interleukin (IL)-3, IL-5, or granulocyte-macrophage colony-stimulating factor (GM-CSF)-induced expression of adhesion molecules including very late antigen 4 (CD49 d), macrophage antigen-1 (CD11b), leukocyte function-associated antigen-1 (CD11a/CD18), intercellular adhesion molecule (ICAM)-1, and ICAM-3 on eosinophils. The expression of adhesion molecules and nuclear factor (NF)-kappaB pathway was measured by flow cytometry and cDNA expression array, respectively. The phosphorylation of inhibitor kappaB-alpha and p38 mitogen-activated protein kinase (MAPK) was detected by Western blot, whereas NF-kappaB activity was measured by electrophoretic mobility shift assay. IL-3, IL-5, and GM-CSF could enhance p38 MAPK and NF-kappaB activity and induce ICAM-1, CD11b, and CD18 expressions on eosinophils. They could suppress ICAM-3 expression, but had no effect on CD49 d expression. Either SB 203580 or MG-132 was able to offset the cytokine-induced expression of ICAM-1. Only SB 203580 could reverse the effect on CD11b, CD18, and ICAM-3 expressions. Therefore, the expression of ICAM-1 might involve both p38 MAPK and NF-kappaB activities, whereas the regulation of CD11b, CD18, and ICAM-3 expressions might be mediated through p38 MAPK but not NF-kappaB. These cytokines therefore play a crucial role, via the p38 MAPK and NF-kappaB pathways, in the expression of important adhesion molecules on eosinophils in allergic inflammation.
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PMID:Interleukin-3, -5, and granulocyte macrophage colony-stimulating factor-induced adhesion molecule expression on eosinophils by p38 mitogen-activated protein kinase and nuclear factor-[kappa] B. 1260 Aug 15

In 16HBE14o- human bronchial epithelial cells, maximal tumor necrosis factor (TNF)-alpha-induced interleukin (IL)-8 expression depends on the activation of two distinct signaling pathways, one constituted in part by activator protein (AP)-1 and the other by nuclear factor (NF)-kappaB. We examined the upstream signaling intermediates responsible for IL-8 and granulocyte-macrophage colony-stimulating factor (GM-CSF) expression in this system, hypothesizing that p21 Ras and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase kinase (MEKK)-1 function as common upstream activators of both the AP-1 and NF-kappaB pathways. TNF-alpha treatment induced both Ras and MEKK1 activation. Dominant-negative forms of Ras (N17Ras) and MEKK1 (MEKK1-KM) each inhibited TNF-alpha-induced transcription from IL-8 and GM-CSF promoters. Ras was required for maximal activation of extracellular signal-regulated kinase (ERK) and Jun amino terminal kinase (JNK) as well as AP-1 and NF-kappaB transcriptional activities, but not for activation of IkappaB kinase (IKK)-beta, an upstream activator of NF-kappaB. MEKK1 was required for maximal activation of ERK, JNK, and IKK, as well as for maximal AP-1 and NF-kappaB transcriptional activities. We conclude that Ras regulates TNF-alpha-induced chemokine expression by activating the AP-1 pathway and enhancing transcriptional function of NF-kappaB, whereas MEKK1 activates both the AP-1 and NF-kappaB pathways.
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PMID:Ras and mitogen-activated protein kinase kinase kinase-1 coregulate activator protein-1- and nuclear factor-kappaB-mediated gene expression in airway epithelial cells. 1260 Aug 18

Survival and proliferation of cells of a human myelo-erythroid CD34+ leukemia cell line (TF-1) depend on the presence of granulocyte-macrophage colony-stimulating factor or interleukin-3. Upon hormone withdrawal these cells stop proliferating and undergo apoptotic process. In this report we demonstrate that a controlled increase in [Ca2+]i induces hormone-independent survival and proliferation of TF-1 cells. We found that moderate elevation of [Ca2+]i by the addition of cyclopiasonic-acid protected TF1 cells from apoptosis. Furthermore, a higher, but transient elevation of [Ca2+]i by ionomycin treatment induced cell proliferation. In both cases caspase-3 activity was reduced, and Bcl-2 was up-regulated. Higher elevation of [Ca2+]i by ionomycin induced MEK-dependent biphasic ERK1/2 activation, sufficient to move the cells from G0/G1 to S/M phases. Meanwhile, activation of ERK1/2, phosphorylation of the Elk-1 transcription factor, and, consequently, a substantial elevation of Egr-1 and c-Fos levels and AP-1 DNA binding were observed. Moderate elevation of [Ca2+]i, on the other hand, caused a delayed monophasic activation of ERK1/2 and Elk-1 that was accompanied with only a small increase of Egr-1 and c-Fos levels and AP-1 DNA binding. The specific MEK-1 kinase inhibitor, PD98059, inhibited all the effects of increasing [Ca2+]i, indicating that the MAPK/ERK pathway activation is essential for TF-1 cell survival and proliferation. Based on these results we suggest that the elevation of the [Ca2+]i may influence the cytokine dependence of hemopoietic progenitors and may contribute to pathological hematopoiesis.
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PMID:Calcium induces cell survival and proliferation through the activation of the MAPK pathway in a human hormone-dependent leukemia cell line, TF-1. 1264 64

Juvenile myelomonocytic leukemia is an aggressive neoplasia of early childhood. Only allogeneic stem cell transplantation (SCT) offers a long-term cure. In the absence of an HLA-matched family donor, early SCT from an unrelated donor will be the treatment of choice for most children. With clear evidence of a graft-versus-leukemia effect and a high post-transplant relapse rate, outcome of SCT will depend, in part, on the management of immunosuppression during the procedure. The impact of pretransplant cytoreductive treatment, such as intensive chemotherapy, splenectomy, or 13-cis retinoic acid, is unclear. Hypersensitivity for granulocyte-macrophage colony-stimulating factor and pathologic activation of the Ras/MAPK pathway play an important role in the pathophysiology of juvenile myelomonocytic leukemia and will provide the opportunity for several novel therapy approaches.
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PMID:Juvenile myelomonocytic leukemia. 1271 97

Stimulation of human neutrophils with granulocyte-macrophage colony-stimulating factor (GM-CSF) or tumor necrosis factor-alpha (TNF) results in increased superoxide (O2-) release and adherence. O2- release and adherence are dependent on activation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). Possible participation of serine proteases in GM-CSF- or TNF-induced activation of human neutrophils was explored with various serine protease inhibitors, including phenylmethylsulfonyl fluoride, L-1-tosylamido-2-phenylethyl-chloromethyl ketone and N-alpha-p-tosyl-L-lysine-chloromethyl ketone. GM-CSF- or TNF-induced O2- release and adherence were inhibited in parallel by pretreatment of neutrophils with these inhibitors. On the other hand, GM-CSF- or TNF-induced phosphorylation of ERK and p38 MAPK was unaffected by these inhibitors at the concentrations effective for the inhibition of O2- release and adherence. These findings suggest that serine proteases are involved in GM-CSF- and TNF-induced O2- release and adherence in human neutrophils and that serine proteases function downstream or independently of the activation of ERK and p38 MAPK.
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PMID:Serine protease inhibitors inhibit superoxide release and adherence in human neutrophils stimulated by granulocyte-macrophage colony-stimulating factor and tumor necrosis factor-alpha. 1273 68

Phagocytosis of complement-opsonized targets is a primary function of neutrophils at sites of inflammation, and the clearance of neutrophils that have phagocytosed microbes is important for the resolution of inflammation. Our previous work suggests that phagocytosis leads to rapid neutrophil apoptosis that is inhibited by antibody to the beta2 integrin, Mac-1, and requires NADPH oxidase-derived reactive oxygen species (ROS) generated during phagocytosis. Here we report that phagocytosis-induced cell death (PICD) does not occur in Mac-1-deficient murine neutrophils, suggesting that PICD proceeds through a bona fide Mac-1-dependent pathway. A sustained, intracellular oxidative burst is associated with PICD. Furthermore, PICD does not require traditional death receptors, Fas, or tumor necrosis factor (TNF) receptor. TNF but not Fas synergizes with phagocytosis to enhance significantly PICD by increasing the oxidative burst, and this is Mac-1-dependent. Phagocytosis-induced ROS promote cleavage/activation of caspases 8 and 3, key players in most extrinsic ("death receptor") mediated pathways of apoptosis, and caspases 8 and 3 but not caspase 9/mitochondria, are required for PICD. This suggests that ROS target the extrinsic versus the intrinsic ("stress stimulus") apoptotic pathway. Phagocytosis also triggers a competing MAPK/ERK-dependent survival pathway that provides resistance to PICD likely by down-regulating caspase 8 activation. The anti-apoptotic factor granulocyte-macrophage colony-stimulating factor (GM-CSF) significantly enhances ROS generation associated with phagocytosis. Despite this, it completely suppresses PICD by sustaining ERK activation and inhibiting caspase 8 activation in phagocytosing neutrophils. Together, these studies suggest that Mac-1-mediated phagocytosis promotes apoptosis through a caspase 8/3-dependent pathway that is modulated by NADPH oxidase-generated ROS and MAPK/ERK. Moreover, TNF and GM-CSF, likely encountered by phagocytosing neutrophils at inflammatory sites, exploit pro-(ROS) and anti-apoptotic (ERK) signals triggered by phagocytosis to promote or suppress PICD, respectively, and thus modulate the fate of phagocytosing neutrophils.
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PMID:Elucidation of molecular events leading to neutrophil apoptosis following phagocytosis: cross-talk between caspase 8, reactive oxygen species, and MAPK/ERK activation. 1273 63


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