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)

We have identified, in Xenopus oocyte cytosol, a protein kinase named REKS (Ras-dependent extracellular signal-regulated kinase (ERK)/mitogen-activated protein kinase kinase (MEK) stimulator), which phosphorylates and activates recombinant ERK2 through recombinant MEK in a recombinant GTP gamma S (guanosine 5'-(3-O-thio)triphosphate)-Ras-dependent manner. We show here that this REKS activity is synergistically enhanced by a combination of mammalian recombinant GTP gamma S-KiRas and 14-3-3 protein purified from rat brain. 14-3-3 protein is known to activate tyrosine and tryptophan hydroxylases, to modulate the protein kinase C activity, to stimulate secretion, and to show phospholipase A2 activity per se. 14-3-3 protein did not affect the MEK activity. 14-3-3 protein neither interacted with Ki-Ras nor affected the neurofibromin activity to stimulate the GTPase activity of Ki-Ras under the conditions where the recombinant N-terminal fragment of c-Raf-1 inhibited it. These results suggest that 14-3-3 protein has an additional function in the regulation of the Ras-MEK-ERK cascade pathway through the activation of REKS.
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PMID:Synergistic activation by Ras and 14-3-3 protein of a mitogen-activated protein kinase kinase kinase named Ras-dependent extracellular signal-regulated kinase kinase stimulator. 808 86

Receptors for interleukins, colony stimulating factors, and hormones have a homology in their extracellular regions, characterized by the conserved cysteine residues and the tryptophan-serine-x-tryptophan-serine motif, thus, they are classified to the type 1 cytokine receptor superfamily. Janus tyrosine kinase (JAKs) have been found to be involved in the signal transduction through type I cytokine receptors. JAKs associate with the membrane proximal region in the cytoplasmic domain having box1 and box2, which are conserved among the family, and upon the stimulation JAKs can be aggregated following the receptor dimerization and activated probably by transphosphorylation. JAKs then phosphorylate the receptor and various signal transducing molecules, including STATs (signal transducer and activator of transcriptions) and other SH2-containing adapter molecules. STATs were initially identified as transcription factors containing a SH2 domain and regulating interferons-inducible genes. STATs can be tyrosine phosphorylated by JAKs and form dimer (either hetero- or homo-dimers) to enter the nucleus, resulting in the expression of a set of genes. On the other hand, adapter molecules such as Shc, GRB2, and SHP-2 have been shown to link the cytokine receptors to Ras, followed by the activation of the Raf-MEK-MAP kinase pathway, leading to the activation of various transcription factors in the nucleus. These two signals are generated by different ways upon the stimulation of the receptors and they elicit a variety of biological functions in various cell types. In this review, we will discuss the mechanism by which cytokines activate JAKs, STATs, and a variety of adapter molecules. We further discuss the roles of each signal transduction pathways in the expression of biological activities of cytokines.
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PMID:Signal transduction through cytokine receptors. 991 44

The leukocyte NADPH oxidase of neutrophils is a membrane-bound enzyme that catalyzes the production of O2- from oxygen using NADPH as the electron donor. Dormant in resting neutrophils, the enzyme acquires catalytic activity when the cells are exposed to appropriate stimuli. During activation, the cytosolic oxidase components p47phox and p67phox migrate to the plasma membrane, where they associate with cytochrome b558, a membrane-integrated flavohemoprotein, to assemble the active oxidase. In whole cells and under certain circumstances in the cell-free system, the phosphorylation of p47phox mediates the activation process. It has been proposed that conformational changes in the protein structure of cytosolic factor p47phox may be an important part of the activation mechanism. The total protein steady-state intrinsic fluorescence (an emission maximum of 338 nm) exhibited by the tryptophan residues of p47phox was substantially decreased, reflecting on the conformational change that occurs when p47phox was phosphorylated with protein kinase C. We show here that the phosphorylation of p47phox by protein kinase A or mitogen-activated protein kinase, however, had little effect on the intrinsic fluorescence of p47phox. In addition, the present experiments indicate that in the mutant p47phoxS379A, only the single S-->A mutation appears to be a major importance for the function of p47phox, which is able to undergo the change in conformation that takes place when p47phox is phosphorylated by protein kinase C.
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PMID:Kinase-dependent change in the conformation of the leukocyte NADPH oxidase subunit p47phox. 1067 33

Several non-peptidic opioids have been synthesized recently as part of a program to develop selective delta receptor agonists. In this study, the affinities of a set of compounds for cloned delta and mu opioid receptors expressed in HEK 293 cell lines were determined by competition analysis of [3H]bremazocine binding to membrane preparations. All compounds studied exhibited high affinity and selectivity, with apparent dissociation constants in the range of 0.6-1.7 nM for the delta opioid receptor and 240-1165 nM for the mu opioid receptor. We next sought to determine which domain of the delta receptor was critical for mediating the highly selective binding by analysis of ligand affinities for mu/delta receptor chimeras. Receptor binding profiles suggested that a critical site of receptor/ligand interaction was located between transmembrane domain 5 (TM5) and TM7 of the delta receptor. Substitution of tryptophan 284, located at the extracellular surface of TM6, with lysine, which is found at the equivalent position in the mu opioid receptor, led to a spectrum of effects on affinities, depending on the ligand tested. Affinities of SB 219825 and SB 222941 were particularly sensitive to the substitution, displaying a 50-fold and 70-fold decrease in affinity, respectively. Activities of the delta receptor-selective agonists were tested in two functional assays. Brief exposure of HEK 293 cells expressing delta opioid receptors with selective ligands induced phosphorylation of MAP kinase, although the non-peptidic ligands were less efficacious than the enkephalin derivative DADL (Tyr-D-Ala-Gly-Phe-D-Leu). Similarly, chronic exposure of HEK 293 cells expressing delta opioid receptors with selective, non-peptidic ligands, with the exception of SB 206848, caused receptor down-regulation, however, the SB compounds were less efficacious than DADL.
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PMID:Pharmacological profiles of selective non-peptidic delta opioid receptor ligands. 1103 49

Integrin transmembrane receptors generate multiple signals, but how they mediate specific signaling is not clear. Here we test the hypothesis that particular sequences along the beta(1) integrin cytoplasmic domain may exist that are intimately related to specific integrin-mediated signaling pathways. Using systematic alanine mutagenesis of amino acids conserved between different beta integrin cytoplasmic domains, we identified the tryptophan residue at position 775 of human beta(1) integrin as specific and necessary for integrin-mediated protein kinase B/Akt survival signaling. Stable expression of a beta(1) integrin mutated at this amino acid in GD25 beta(1)-null cells resulted in reduction of Akt phosphorylation at both Ser(473) and Thr(308) activation sites. As a consequence, the cells were substantially more sensitive to serum starvation-induced apoptosis when compared with cells expressing wild type beta(1) integrin. This inactivation of Akt resulted from increased dephosphorylation by a localized active population of protein phosphatase 2A. Both Akt and protein phosphatase 2A were present in beta(1) integrin-organized cytoplasmic complexes, but the activity of this phosphatase was 2.5 times higher in the complexes organized by the mutant integrin. The mutation of Trp(775) specifically affected Akt signaling, without effects on other integrin-activated pathways including phosphoinositide 3-kinase, MAPK, JNK, and p38 nor did it influence activation of the integrin-responsive kinases focal adhesion kinase and Src. The identification of Trp(775) as a specific site for integrin-mediated Akt signaling supports the concept of specificity of signaling along the integrin cytoplasmic domain.
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PMID:Specific beta1 integrin site selectively regulates Akt/protein kinase B signaling via local activation of protein phosphatase 2A. 1263 11

In the present study, we investigated whether activation of protease-activated receptor type 2 (PAR-2) with SLIGRL (SL)NH2, a short mimetic agonistic peptide, directly stimulates pepsinogen secretion from gastric-isolated, pepsinogen-secreting (chief) cells. Immunostaining of gastric-dispersed chief cells with a specific anti-PAR-2 antibody demonstrated expression of PAR-2 receptors on membrane and cytoplasm. SL-NH2 and trypsin potently stimulated pepsinogen secretion (EC50 = 0.3 nM) and caused Ca2+ mobilization (EC50 = 0.6 nM). In contrast to SL-NH2, the scramble peptide LSIGRL-NH2 failed to stimulate pepsinogen release. Exposure to SL-NH2 also resulted in ERK1/2 phosphorylation and activation. Exposure of chief cells to phosphotyrosine kinase inhibitors and 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one, a selective MEK inhibitor, significantly reduced secretion induced by SL-NH2. Pepsinogen secretion induced by SL-NH2 was desensitized by pretreating the cells with the mimetic peptide and trypsin, and exposure to SL-NH2 abrogates pepsinogen secretion induced by carbachol and CCK-8, but not secretion induced by secretin and vasointestinal peptide. Exposure to Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2 (substance P) but not to calcitonin gene-related peptide increased pepsinogen release. The neurokinin-1 receptor antagonist, N-acetyl-l-tryptophan 3,5-bis(trifluoromethyl)benzyl ester, inhibited substance P-stimulated pepsinogen secretion, whereas it did not affect secretion induced by SL-NH2. Collectively, these data indicate that PAR-2 is expressed on gastric chief cells and that its activation causes a Ca2+-ERK-dependent stimulation of pepsinogen secretion.
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PMID:PAR-2 modulates pepsinogen secretion from gastric-isolated chief cells. 1274 62

3-Hydroxykynurenine (3-HK), an endogenous tryptophan metabolite, is known to have toxic effects in brain. However, the molecular mechanism of the toxicity has not been well identified. In this study, we investigated the involvement of MAPK/extracellular signal-regulated kinase (ERK) in the 3-HK-induced neuronal cell damage. Our results showed that 3-HK induced apoptotic neuronal cell death and ERK phosphorylation occurred during cell death. Inhibition of ERK activation using PD98059 considerably increased cell death. Furthermore, cell death was preceded by mitochondrial malfunction including collapse of mitochondrial membrane potential (DeltaPsi(m)) and cytochrome c release from mitochondria to the cytosol. Interestingly, inhibition of ERK dramatically increased mitochondrial malfunction, and enhanced caspase activation, resulting in enhanced neuronal cell death. Thus, our results show that ERK plays a protective role by maintaining mitochondrial function and regulating caspase activity under conditions of cellular stress.
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PMID:Mitogen-activated protein kinase/extracellular signal-regulated kinase attenuates 3-hydroxykynurenine-induced neuronal cell death. 1472 Feb 14

Mild doses of oxidative stress in the heart correlate with the induction of apoptosis or hypertrophy in cardiomyocytes (CMCs) and fibrosis or proliferation of fibroblasts. Three branches of mitogen-activated protein kinases (MAPKs), i.e., c-Jun N-terminal kinases (JNKs), extracellular signal-related kinases 1 and 2 (ERK1/2), and p38, are activated by oxidants in a variety of cell types, including CMCs. However, the initiation process of these signaling pathways remains unsolved. We explored the role of the epidermal growth factor (EGF) receptor in H(2)O(2)-induced MAPK activation using two different cell types from the same organ: CMCs and heart fibroblasts (HFs). Pretreatment of each cell type with EGF revealed differences in how CMCs and HFs responded to subsequent treatment with H(2)O(2): in CMCs, the second treatment resulted in little further activation of JNKs and ERK1/2, whereas HFs retained the full response of JNKs and ERK1/2 activation by H(2)O(2) regardless of EGF pretreatment. AG-1478 [4-(3'-chloroanilino)-6,7-dimethoxy-quinazoline], a pharmacologic inhibitor of the EGF receptor tyrosine kinase, inhibited JNK and ERK1/2 activations but not p38 in both cell types. The data using the Src inhibitor PP2 [4-amino-5-(4-chlorophenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine] resemble those found when using AG-1478 in either cell type. Pharmacologic inhibitors of matrix metalloproteinases (MMPs) further illustrated the difference between the two cell types. In HFs, MMP inhibitors GM6001 [N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl]-l-tryptophan methylamide] and BB2516 [[2S-[N4(R(*)),2R(*),3S(*)]]-N4-[2,2-dimethyl-1-[(methylamino)carbonyl]propyl]-N1,2-dihydroxy-3-(2-methylpropyl)butanediamide, marimastat] inhibited JNKs and ERK1/2 activation without affecting p38 activation by H(2)O(2) inhibitors. In contrast, these MMP failed to significantly inhibit the activation of JNKs, ERKs, or p38 in CMCs. These data suggest the complexity of the cell type-dependent signaling web initiated by oxidants in the heart.
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PMID:Epidermal growth factor receptor-dependent and -independent pathways in hydrogen peroxide-induced mitogen-activated protein kinase activation in cardiomyocytes and heart fibroblasts. 1557 83

C-reactive protein (CRP) is significantly associated with the risk of ischemic cardiovascular disease in epidemiological studies. To explore if CRP has a functional role, we investigated its effect on the gene expression profile of vascular endothelial cells. Human vascular endothelial cells (human umbilical vein endothelial cells and human aortic endothelial cells) were incubated with CRP at various concentrations (0-10 mug/ml). Microarray analysis showed that a total of 11 genes increased (IL-8, core promoter element binding protein, activin A, monocyte chemoattractant protein 1, Exostoses 1, Cbp/p300-interacting transactivator with Glu/Asp-rich COOH-terminal domain 2, plasminogen activator inhibitor 1, fibronectin-1, gravin, connexin43, and sortilin-related receptor-1) and 6 genes decreased (methionine adenosyltransferase 2A, tryptophan-rich basic protein, reticulocalbin 1, membrane-associated RING-CH protein VI, cytoplasmic dynein1, and annexin A(1)) by more than twofold for their mRNA levels. IL-8 was the most significantly upregulated gene (13.6-fold), which demonstrated a clear dose- and time-dependent pattern revealed by quantitative real-time PCR. Cell adhesion assay showed that CRP enhanced the monocyte adhesion to endothelial cell monolayer by 2-fold (P < 0.01), which was partially blocked by an anti-IL-8 antibody (34.2% inhibition, P < 0.01). Inhibition of ERK MAPK pathway using U0126 prevented CRP-induced IL-8 upregulation, and Western blot analysis revealed a rapid activation of ERK1/2 after CRP stimulation. These data showed that CRP can significantly influence gene expressions in vascular endothelium. The CRP-responsive genes suggested that CRP may have a broad functional role in cell growth and differentiation, vascular remodeling and solid tumor development.
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PMID:Effect of C-reactive protein on gene expression in vascular endothelial cells. 1559 Oct 95

Protein phosphorylation is a critical regulatory strategy. New tools are necessary which may be used to interrogate and are responsive to the activities of protein kinases and phosphatases. We have used protein design to develop a protein motif, termed a protein kinase-inducible domain, whose structure is dependent on its phosphorylation state. Based on an EF hand calcium-binding loop, the key design element is the replacement of a structurally critical Glu residue, which binds metal in a bidentate manner, with a serine residue, which is expected to bind metal tightly when phosphorylated but poorly when not phosphorylated. The design comprises an EF hand consensus sequence, a tryptophan at residue 7 to sensitize lanthanide luminescence, and the recognition sequence of a serine/threonine kinase. Designed peptides, which contain minimal substrate recognition motifs of the protein kinases PKA, PKC, or the MAP kinase Erk, form complexes with Tb3+ when phosphorylated, showing strong Tb3+ luminescence emission at 544 nm, but show weak luminescence when not phosphorylated. The change in fluorescence on phosphorylation is comparable to or greater than that observed in described kinase sensors. Site-specific lanthanide binding was confirmed by NMR with diamagnetic and paramagnetic metals. The kinase-inducible domain peptides comprise an expressible sequence, potentially enabling their use as genetically encoded tags of protein kinase activity. The motif is general and potentially applicable to the majority of serine/threonine kinases.
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PMID:Design of a protein kinase-inducible domain. 1663 98


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