Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P51812 (mitogen-activated protein)
 10,636 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Background- Mechanical unloading of the heart with a left ventricular assist device (LVAD) leads to favorable changes in the biology of the failing cardiac myocyte. To determine a potential mechanism for these improvements, we examined the regulation of mitogen-activated protein kinases (MAPKs) in the failing heart in the presence and absence of LVAD support. Methods and Results- We examined the degree of activation (ie, phosphorylation) of p44/42 extracellularly regulated kinase, p38 kinase, and c-Jun N-terminal kinase (JNK1/2), and the corresponding activity levels of these MAPKs in myocardial samples obtained from 11 patients with LVAD support and in 11 patients without LVAD support. MAPK activity was also examined in an additional 6 patients from whom paired samples were obtained before and after LVAD support. The activity of p44/42 and JNK1/2 were reduced significantly, whereas p38 activity levels were significantly increased after LVAD support. We examined functional parameters that are linked to MAPK activation, namely cardiac myocyte hypertrophy and apoptosis. Both cardiac myocyte cell size and the incidence of cardiac myocyte apoptosis were significantly reduced after LVAD support. Conclusions- Mechanical unloading of the failing heart leads to differential regulation of MAPKs. These changes in MAPK activity are associated with changes in myocyte hypertrophy and viability, suggesting a potential mechanistic basis for some of the observed salutary changes after LVAD support.
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PMID:Differential regulation of mitogen-activated protein kinases in the failing human heart in response to mechanical unloading. 1169 64

This study examined the role of signal transduction and apoptosis in malignant transformation induced by arsenic. Prior study showed that chronic arsenite exposure (500 nM, > or =18 weeks) induced malignant transformation in rat liver TRL 1215 cells. In the present work, these transformed cells were compared with passage-matched control cells. In addition, TRL 1215 cells were treated subchronically (up to 6 weeks) with arsenic (termed pre-transformed cells) to define events occurring prior to arsenic-induced transformation. Flow cytometry using annexin/FITC revealed that arsenic-induced apoptosis in transformed cells was markedly suppressed in comparison to control or pre-transformed cells. Ro318220, a strong activator of JNK, enhanced arsenite-induced apoptosis in transformed cells. Densitometric analysis of western blots revealed that the ratios of both Bcl-x(L)/Bax and Bcl-2/Bax were significantly increased (>2.5-fold) in arsenic-transformed cells. Transformed, pre-transformed and control cells were treated with arsenic and levels of phosphorylated extracellular signal-regulated kinases, ERK1/2, JNK1/2 and p38 were determined by western blot analysis. The three mitogen-activated protein kinases (MAPKs) were phosphorylated in a dose-dependent fashion in all cell types. However, the levels of phosphorylated JNK1/2 were markedly decreased in the arsenic-transformed cells, whereas in pre-transformed cells the levels of phosphorylated MAPKs remained the same as in control cells. JNK kinase activity was suppressed in transformed cells whereas Ro318220 enhanced this activity. Thus, during arsenic-induced malignant transformation resistance to apoptosis develops, possibly due to perturbation of the JNK pathway.
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PMID:Acquisition of apoptotic resistance in arsenic-induced malignant transformation: role of the JNK signal transduction pathway. 1175 36

The mitogen-activated protein (MAP) kinase family is activated in response to a wide variety of external stress signals such as UV irradiation, heat shock, and many chemotherapeutic drugs and leads to the induction of apoptosis. A novel series of pyrrolo-1,5-benzoxazepines have been shown to potently induce apoptosis in chronic myelogenous leukemia (CML) cells, which are resistant to many chemotherapeutic agents. In this study we have delineated part of the mechanism by which a representative compound known as PBOX-6 induces apoptosis. We have investigated whether PBOX-6 induces activation of MAP kinase signaling pathways in CML cells. Treatment of K562 cells with PBOX-6 resulted in the transient activation of two JNK isoforms, JNK1 and JNK2. In contrast, PBOX-6 did not activate the extracellular signal-regulated kinase (ERK) or p38. Apoptosis was found to occur independently of the small GTPases Ras, Rac, and Cdc42 but involved phosphorylation of the JNK substrates, c-Jun and ATF-2. Pretreatment of K562 cells with the JNK inhibitor, dicoumarol, abolished PBOX-6-induced phosphorylation of c-Jun and ATF-2 and inhibited the induced apoptosis, suggesting that JNK activation is an essential component of the apoptotic pathway induced by PBOX-6. Consistent with this finding, transfection of K562 cells with the JNK scaffold protein, JIP-1, inhibited JNK activity and apoptosis induced by PBOX-6. JIP-1 specifically scaffolds JNK, MKK7, and members of the mixed-lineage kinase (MLK) family, implicating these kinases upstream of JNK in the apoptotic pathway induced by PBOX-6 in K562 cells.
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PMID:Activation of the c-Jun N-terminal kinase (JNK) signaling pathway is essential during PBOX-6-induced apoptosis in chronic myelogenous leukemia (CML) cells. 1185 43

The Bcl-2 family member Bad is a pro-apoptotic protein, and phosphorylation of Bad by cytokines and growth factors promotes cell survival in many cell types. Induction of apoptosis by UV radiation is well documented. However, little is known about UV activation of cell survival pathways. Here, we demonstrate that UVB induces Bad phosphorylation at serine 112 in JNK1, RSK2, and MSK1-dependent pathways. Inhibition of mitogen-activated protein (MAP) kinases including ERKs, JNKs, and p38 kinase by the use of their respective dominant negative mutant or a specific inhibitor for MEK1 or p38 kinase, PD98059 or SB202190, resulted in abrogation of UVB-induced phosphorylation of Bad at serine 112. Incubation of active MAP kinase members with Bad protein showed serine 112 phosphorylation of Bad by JNK1 only. However, activated RSK2 and MSK1, downstream kinases of ERKs and p38 kinase, respectively, also phosphorylated Bad at serine 112 in vitro. Cells from a Coffin-Lowry syndrome patient (deficient in RSK2) or expressing an N-terminal or C-terminal kinase-dead mutant of MSK1 were defective for UVB-induced serine 112 phosphorylation of Bad. Furthermore, MAP kinase pathway-dependent serine 112 phosphorylation was shown to be required for dissociation of Bad from Bcl-X(L). These data illustrated that UVB-induced phosphorylation of Bad at serine 112 was mediated through MAP kinase signaling pathways in which JNK1, RSK2, and MSK1 served as direct mediators.
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PMID:Activation of JNK1, RSK2, and MSK1 is involved in serine 112 phosphorylation of Bad by ultraviolet B radiation. 1198 83

Heme oxygenase-1 (HO-1) is an enzyme that is highly inducible by various cellular stressors, especially oxidant injury. Our laboratory and others have demonstrated that induction of HO-1 exerts an antiinflammatory effect both in vitro and in vivo. We hypothesized that carbon monoxide (CO), a major catalytic byproduct of heme catalysis by HO-1, may mediate this antiinflammatory effect by modulating signal transduction pathways, in particular the mitogen-activated protein (MAP) kinase pathway. Confluent primary cultures of rat pulmonary artery endothelial cells (RPAEC) were treated with tumor necrosis factor-alpha (TNF-alpha; 50 ng/ml), and whole-cell extracts were assayed for phosphorylated ERK1/2, JNK1/2, and p38 MAP kinases. These three major MAP kinase pathways were activated by TNF-alpha in a time-dependent manner. RPAEC treated with TNF-alpha in the presence of a low concentration of CO (1%) exhibited marked attenuation of the phosphorylation of ERK1/2 MAP kinase when compared with cells treated with TNF-alpha alone. A similar effect was seen on the upstream MEK 1/2 kinase. Interestingly, CO (1%) accentuated TNF-alpha-induced phosphorylated p38 MAP kinase. These effects of exogenous CO on the ERK1/2 and p38 systems could be replicated by overexpression of HO-1 in RPAEC, using an adenoviral vector. As these MAP kinases are implicated in the regulation of various inflammatory molecules and adhesion molecules, our data provide a potential mechanism by which HO-1, acting via CO, may modulate the inflammatory response by differential activation of the MAP kinase pathway.
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PMID:Differential modulation by exogenous carbon monoxide of TNF-alpha stimulated mitogen-activated protein kinases in rat pulmonary artery endothelial cells. 1200 75

In this study, we investigated the effects of proteasome inhibibors (MG132 and lactacystin) on interleukin (IL)-8 induction. In human epithelial A549 cells, MG132 and lactacystin induced IL-8 release within the range of 0.1-30 microM. The effect of MG132 resulted from IL-8 gene transcription and was blocked by PD 98059, but was unaffected by GF109203X, Ro 31-8220, or SB 203580. Mutational analysis of the 5' flanking region of the IL-8 gene revealed that activator protein (AP)-1-binding element, but not that element responsive to nuclear factor (NF)-IL-6 or NF-kappaB, was necessary for MG132 stimulation. Consistent with this, MG132 and lactacystin increased the DNA-binding and reporter activities of AP-1, but reduced cytokine-elicited kappaB activation. Moreover, AP-1 stimulation was associated with increased extracellular signal-related kinase (ERK), mitogen-activated protein/ERK kinase (MEK), and c-Jun N-terminal kinase (JNK) phosphorylation, whereas IL-8 activity was sensitive to the dominant-negative mutants of JNK1, JNK2, SEK, ASK, ERK2, and Ras, but not those of MEKK1, TAK, and p38 mitogen-activated protein kinase. In addition, activations of the IL-8 gene and AP-1 by MG132 and lactacystin were inhibited by GSH and NAC. Herein we present a novel action of proteasome inhibitors, possibly through ROS production, of targeting the upstream signaling molecules, ERK and JNK, which leads to AP-1 activation and IL-8 gene expression.
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PMID:Proteasome inhibitors stimulate interleukin-8 expression via Ras and apoptosis signal-regulating kinase-dependent extracellular signal-related kinase and c-Jun N-terminal kinase activation. 1215 16

We investigated intracellular signalling pathways for apoptosis induced by epigallocatechin-3-gallate (EGCG) as compared with those induced by a toxic chemical substance (etoposide, VP16) or the death receptor ligand [tumour necrosis factor (TNF)]. EGCG as well as VP16 and TNF induced activation of two apoptosis-regulating mitogen-activated protein (MAP) kinases, namely c-Jun N-terminal kinase (JNK) and p38 MAP kinase, in both human leukaemic U937 and OCI-AML1a cells. In U937 cells, the apoptosis and activation of caspases-3 and -9 induced by EGCG but not VP16 and TNF were inhibited with SB203580, a specific inhibitor of p38, while those induced by EGCG and VP16 but not TNF were inhibited with SB202190, a rather broad inhibitor of JNK and p38. In contrast, the EGCG-induced apoptosis in OCI-AML1a cells was resistant to SB203580 but not to SB202190. Unlike TNF, EGCG did not induce the activation of nuclear factor-kappaB but rather induced the primary activation of caspase-9. N -Acetyl-L-cysteine (NAC) almost completely abolished apoptosis induced by EGCG under conditions in which the apoptosis induced by VP16 or TNF was not affected. The JNK/p38 activation by EGCG was also potently inhibited by NAC, whereas those by VP16 and TNF were either not or only minimally affected by NAC. In addition, dithiothreitol also suppressed both apoptosis and JNK/p38 activation by EGCG, and EGCG-induced activation of MAP kinase kinase (MKK) 3/6, MKK4 and apoptosis-regulating kinase 1 (ASK1) was suppressed by NAC. Dominant negative ASK1, MKK6, MKK4 and JNK1 potently inhibited EGCG-induced cell death. EGCG induced an intracellular increase in reactive oxygen species and GSSG, both of which were also inhibited by NAC, and the decreased synthesis of glutathione rendered the cell susceptible to EGCG-induced apoptosis. Taken together these results strongly suggest that EGCG executed apoptotic cell death via an ASK1, MKK and JNK/p38 cascade which is triggered by NAC-sensitive intracellular oxidative events in a manner distinct from chemically induced or receptor-mediated apoptosis.
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PMID:Oxidation-triggered c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase pathways for apoptosis in human leukaemic cells stimulated by epigallocatechin-3-gallate (EGCG): a distinct pathway from those of chemically induced and receptor-mediated apoptosis. 1220 15

Vomitoxin (VT) and other trichothecene mycotoxins mediate a broad range of immunotoxic effects via the induction of inflammation-associated genes in leukocytes. The purpose of this study was to test the hypothesis that VT induces cyclooxygenase-2 (COX-2) gene expression in macrophages and that this is regulated at the level of mitogen-activated protein kinases (MAPKs). Exposure of the murine macrophage cell line RAW 264.7 to 50-250 ng/ml VT for 24 h markedly enhanced the production of prostaglandin E(2) (PGE(2)), a major COX-2 metabolite. PGE(2) elevation was preceded by increases in COX-2 mRNA (2 h) and COX-2 protein (15 h) in VT-treated cells. VT induced rapid (15 min) and persistent (up to 240 min) phosphorylation of extracellular, signal regulated protein kinases 1 and 2 (ERK1/2) and p38 MAPK as well as a rapid (15 min) but transient (up to 60 min) phosphorylation of c-Jun N-terminal kinases 1 and 2 (JNK1/2). The ERK inhibitor PD98059 and p38 inhibitor SB203580 suppressed VT-induced PGE(2) and COX-2 protein expression, whereas impairment of JNK function by transient transfection with a dominant negative (dn) JNK vector had no effect on COX-2 protein expression. Relatedly, in cells transfected with a COX-2 promoter-luciferase construct, PD98059- and SB203580-, but not dnJNK-treatment, suppressed VT-induced luciferase transcription. VT also increased COX-2 mRNA stability, and this was inhibited by PD98059 but not by SB203580. Taken together, these results indicate that VT-induced PGE(2) production and COX-2 expression by elevating transcriptional activity and mRNA stability. Enhanced transcriptional activity was modulated by ERK and p38 signaling pathways, whereas mRNA stability was promoted exclusively by VT-activated p38 phosphorylation. These data provide insight into possible general mechanisms by which VT and other trichlothecenes upregulate proinflammatory genes and impart immunotoxicity.
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PMID:Vomitoxin-induced cyclooxygenase-2 gene expression in macrophages mediated by activation of ERK and p38 but not JNK mitogen-activated protein kinases. 1237 76

TEL is a nuclear phosphoprotein that belongs to a member of the ETS family transcription factors. TEL acts as a tumor suppressor and is essential for establishing hematopoiesis in neonatal bone marrow. Because TEL possesses multiple putative mitogen-activated protein (MAP) kinase phosphorylation sites, we here investigated functional regulation of TEL via stress signaling pathways. We showed that TEL becomes phosphorylated in vivo by activated p38 but not by JNK1. The constitutive and inducible phosphorylation sites were found to be Ser(22) and Ser(257), respectively. TEL bound to p38 and was directly phosphorylated in vitro by p38. In vivo p38-dependent phosphorylation reduced trans-repressional abilities of TEL through ETS-binding consensus site. These data indicate that TEL's functions are potentially regulated by p38 which is activated by various kinds of stresses. TEL could be a constituent downstream of the specific MAP kinase in the signal transduction system.
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PMID:Functional regulation of TEL by p38-induced phosphorylation. 1243 97

One important action of growth factors is their participation in tissue repair; however, the signaling pathways involved are poorly understood. In a model of corneal wound healing, we found that two paracrine growth factors, hepatocyte growth factor (HGF) and keratinocyte growth factor (KGF), induced rapid and marked activation and prompt nuclear accumulation of phospho-p38 (p-p38) and -ERK1/2 (p-ERK1/2), but not of JNK (p-JNK1/2), in corneal epithelial cells. Interruption of p38 and ERK1/2 signaling pathways by pretreatment with inhibitors SB203580 and PD98059 and subsequent stimulation with HGF or KGF abolished the activation and nuclear localization. Inhibition of either one of these mitogen-activated protein kinases, p38 or ERK1/2, induced a robust cross-activation of the other. In immunofluorescence studies of wounded cornea, p-p38, unlike p-ERK1/2, was immediately detectable in epithelium after injury. Inhibition of p38 by SB203580 blocked migration of epithelial cells almost completely. In contrast, PD98059 seemed to slightly increase the migration, through concomitant activation of p38. Unlike ERK1/2, p38 did not significantly contribute to proliferation of epithelial cells. Inhibition of either the ERK1/2 or p38 pathway resulted in delayed corneal epithelial wound healing. Interruption of both signaling cascades additively inhibited the wound-healing process. These findings demonstrate that both p38 and ERK1/2 coordinate the dynamics of wound healing: while growth factor-stimulated p38 induces epithelial migration, ERK1/2 activation induces proliferation. The cross-talk between these two signal cascades and the selective action of p38 in migration appear to be important to corneal wound healing, and possibly wound healing in general, and may offer novel drug targets for tissue repair.
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PMID:p38 and ERK1/2 coordinate cellular migration and proliferation in epithelial wound healing: evidence of cross-talk activation between MAP kinase cascades. 1266 71


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