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:2.7.11.1 (protein kinase)
81,284 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We isolated nardosinone as a neuritogenic substance from Nardostachys chinensis. Nardosinone did not exhibit the neurotrophic activity but caused a marked enhancement of the nerve growth factor (NGF)-mediated neurite outgrowth from PC12D cells. Nardosinone-induced enhancement of the NGF-action was completely blocked by PD98059, a representative mitogen activated protein kinase (MAPK) kinase inhibitor. The microscopic observations indicated that the neurites in response to nardosinone and NGF were quite long and were generally extended to the neighboring cells. These results suggest that nardosinone enhances the NGF-induced neurite outgrowth from PC12D cells probably by amplifying an up-stream step of MAPK kinase in the NGF receptor-mediated intracellular signaling pathway.
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PMID:Nardosinone, a novel enhancer of nerve growth factor in neurite outgrowth from PC12D cells. 1050 50

Anandamide (ANA) inhibits prolactin- and nerve growth factor (NGF)-induced proliferation of human breast cancer cells by decreasing the levels of the 100 kDa prolactin receptor (PRLr) and the high affinity trk NGF receptor, respectively, and by acting via CB(1)-like cannabinoid receptors. However, the intracellular signals that mediate these effects are not known. Here, we show that, in MCF-7 cells: (i) forskolin and the mitogen-activated protein kinase (MAPK) kinase inhibitor PD098059 prevent, and the protein kinase A inhibitor RpcAMPs mimics, the inhibitory effects of ANA on cell proliferation and PRLr/trk expression and (ii) ANA inhibits forskolin-induced cAMP formation and stimulates Raf-1 translocation and MAPK activity, in a fashion sensitive to the selective CB(1) antagonist SR141716A. ANA stimulation of MAPK was enhanced by inhibitors of ANA hydrolysis. Forskolin inhibited MAPK and ANA-induced Raf-1 translocation. These findings indicate that, in MCF-7 cells, ANA inhibits adenylyl cyclase and activates MAPK, thereby exerting a down-regulation on PRLr and trk levels and a suppression of cell proliferation.
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PMID:Involvement of the cAMP/protein kinase A pathway and of mitogen-activated protein kinase in the anti-proliferative effects of anandamide in human breast cancer cells. 1060 28

PC12 and INS-1 cells both express the nerve growth factor (NGF) receptors trkA and p75NTR and the epidermal growth factor receptor (EGF). In PC12 cells, NGF treatment initiates a signaling cascade that ultimately leads to a change of the genetic program of the cell. We have investigated the role of NGF in regulating gene transcription in PC12 and INS-1 cells, in order to define if there are NGF-regulated genes per se. Furthermore, to distinguish between growth factor stimulation via receptor tyrosine kinases in general and NGF-specific changes in gene transcription, we analyzed the effects of EGF on gene transcription. First, we tested the biological activities of fusion proteins consisting of the DNA-binding domain of the yeast transcription factor GAL4 and the phosphorylation-dependent activation domains of the transcription factors Elk1, CREB, ATF2 and c-jun in NGF- or EGF-treated PC12 cells. We found a striking increase in the transcriptional activity of the GAL4-Elk1 fusion protein that is a major substrate for the extracellular signal-regulated protein kinase (ERK). This effect was observed in NGF- as well as in EGF-treated PC12 cells. In INS-1 cells, however, the activity of the GAL4-Elk1 fusion protein was induced by NGF, but not by EGF. The effects of NGF and EGF on gene transcription were subsequently studied with plasmids containing reporter genes under control of the Egr-1, c-jun, HES-1 or Bc12 regulatory sequences. NGF stimulated Egr-1 promoter activities in PC12 and INS-1 cells, although the effect was much more pronounced in PC12 cells than in INS-1 cells. EGF also stimulated Egr-1 promoter activity in both PC12 and INS-1 cells. Stimulation of c-jun promoter activity by NGF was observed only in PC12 cells. Deletion mutagenesis demonstrated the importance of the 12-O-tetradecanoylphorbol-13-acetate response elements within the c-jun promoter for basal and NGF-mediated transcriptional induction. Likewise, NGF activated HES1 and Bcl2 P1 promoter activities in PC12 cells but not in INS-1 cells and EGF did not show any effects on these promoters. We conclude that in PC12 and INS-1 cells, NGF signaling leads to an activation of the ERK subtype of mitogen-activated protein kinases in the nucleus and a subsequent activation of Egr-1 gene transcription. The NGF-induced transcription of the c-jun, HES1 and Bc12 genes is, in contrast, cell type-specific, indicating that NGF can trigger different gene expression programs dependent on the signaling pathways present in a particular cell type. EGF is clearly able to activate gene transcription, suggesting that the differences in the biological activities of EGF and NGF cannot be explained by the inability of EGF to stimulate gene transcription.
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PMID:Nerve growth factor- and epidermal growth factor-regulated gene transcription in PC12 pheochromocytoma and INS-1 insulinoma cells. 1115 83

14-3-3 proteins belong to a family of conserved molecules, which play a regulatory role and participate in signal transduction and checkpoint control pathways. 14-3-3 proteins bind phosphoserine-phosphorylated ligands, such as the Raf-1 kinase and Bad, through recognition of the phosphorylated consensus motif, RSXpSXP (where pS is phosphoserine). Recently, a phosphorylation-independent interaction has been reported to occur between 14-3-3 and a small number of proteins, for example the 43 kDa inositol polyphosphate 5-phosphatase, glycoprotein Ib, p75NTR-associated cell-death executor (NADE) and the bacterial ADP-ribosyltransferase toxin exoenzyme S (ExoS). It has been suggested that specific residues of 14-3-3 proteins are required for activation of the bacterial toxin ExoS. An unphosphorylated peptide derived from a phage display library, known as the R18 peptide, and a synthetic peptide derived from ExoS inhibit the interaction between ExoS and 14-3-3. In this report we identify the amino acid sequence on ExoS which is responsible for its specific interaction with 14-3-3, both in vitro and in vivo. In addition, we believe that this interaction is critical for the ADP-ribosylation of an endogenous target, Ras, by ExoS both in vitro and in vivo. Loss of the 14-3-3-binding site on ExoS results in an ExoS molecule that is unable to efficiently inactivate Ras and shows a reduced capacity to change the morphology of infected cells, together with reduced killing activity.
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PMID:Exoenzyme S binds its cofactor 14-3-3 through a non-phosphorylated motif. 1219 3

In PC12 cells, a well studied model for neuronal differentiation, an elevation in the intracellular cAMP level increases cell survival, stimulates neurite outgrowth, and causes activation of extracellular signal-regulated protein kinase 1 and 2 (ERK1/2). Here we show that an increase in the intracellular cAMP concentration induces tyrosine phosphorylation of two receptor tyrosine kinases, i.e. the epidermal growth factor (EGF) receptor and the high affinity receptor for nerve growth factor (NGF), also termed Trk(A). cAMP-induced tyrosine phosphorylation of the EGF receptor is rapid and correlates with ERK1/2 activation. It occurs also in Panc-1, but not in human mesangial cells. cAMP-induced tyrosine phosphorylation of the NGF receptor is slower and correlates with Akt activation. Inhibition of EGF receptor tyrosine phosphorylation, but not of the NGF receptor, reduces cAMP-induced neurite outgrowth. Expression of dominant-negative Akt does not abolish cAMP-induced survival in serum-free media, but increases cAMP-induced ERK1/2 activation and neurite outgrowth. Together, our results demonstrate that cAMP induces dual signaling in PC12 cells: transactivation of the EGF receptor triggering the ERK1/2 pathway and neurite outgrowth; and transactivation of the NGF receptor promoting Akt activation and thereby modulating ERK1/2 activation and neurite outgrowth.
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PMID:Cyclic AMP induces transactivation of the receptors for epidermal growth factor and nerve growth factor, thereby modulating activation of MAP kinase, Akt, and neurite outgrowth in PC12 cells. 3309 50

Nerve growth factor (NGF) causes a rapid sensitisation of nociceptive sensory neurones to painful thermal stimuli owing to an action on the heat and capsaicin receptor TRPV1 (formerly known as VR1). We have developed a new technique to study this rapid sensitisation of TRPV1 by monitoring the effects of NGF on the increase in intracellular calcium concentration ([Ca2+]i) following exposure to capsaicin. Brief applications of capsaicin caused a rise in [Ca2+]i, and NGF was found to enhance this rise in 37 % of capsaicin-responsive neurones within 2 min. Pathways responsible for transducing the sensitisation of TRPV1 by TrkA, the NGF receptor, were characterised by observing the effects of inhibitors of key members of NGF-activated second messenger signalling cascades. Specific inhibitors of the ras/MEK (mitogen-activated protein and extracellular signal-regulated kinases) pathway and of phospholipase C did not abolish the NGF-induced sensitisation, but wortmannin, a specific inhibitor of phosphatidylinositol-3-kinase (PI3K), totally abolished the effect of NGF. Pharmacological blockade of protein kinase C (PKC) or calcium-calmodulin-dependent protein kinase II (CaMK II) activation also prevented NGF-induced sensitisation, while blockade of protein kinase A (PKA) was without effect. These data indicate that the crucial early pathway activated by NGF involves PI3K, while PKC and CaMK II are also involved, probably at subsequent stages of the NGF-activated signalling pathway.
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PMID:Signalling pathways involved in the sensitisation of mouse nociceptive neurones by nerve growth factor. 1281 88

Neurotrophins are required for the differentiation and survival of several different neuronal subpopulations in the developing nervous system. The PC12 cell line responds to nerve growth factor (NGF) by withdrawing from the cell cycle and acquiring a sympathetic neuron-like phenotype. Previous studies have shown that the activation kinetics of the NGF receptor, TrkA, and downstream protein kinases appear rapid and seemingly transient after NGF treatment of naive PC12 cells. However, maintenance of the neuronal phenotype and survival of differentiated PC12 cells under serum-free conditions require constant NGF exposure. In this study we have addressed the mechanisms that NGF uses to maintain neuronal PC12 cells. We show that TrkA remains phosphorylated at a basal level throughout differentiation of the PC12 cells. The phospho-TrkA levels in the differentiated PC12 cells were diminished by both complete NGF withdrawal and pharmacological inhibition of Trk kinase activity. Intracellular sequestration of the majority of TrkA molecules (both phosphorylated and non-phosphorylated TrkA) and persistent dephosphorylation of the small pool of cell surface TrkA renders the persistent phospho-TrkA signal in the differentiated PC12 cells resistant to partial NGF withdrawal as well as exposure to additional NGF. NGF regulated both extracellular-regulated kinases 1/2 and Akt activity in the differentiated PC12 cells via sustained TrkA activity. Moreover, analysis of transcription using activating protein 1-, serum response element-, and cyclic AMP response element-Luc reporter constructs showed that NGF regulated these promoters through TrkA activity in differentiated PC12 cells. Interestingly, the initial response of the cyclic AMP response element promoter to NGF was delayed, becoming Trk-dependent well beyond the peaks in TrkA and downstream protein kinase signal transduction.
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PMID:Persistent TrkA activity is necessary to maintain transcription in neuronally differentiated PC12 cells. 1290 22

Cyclic phosphatidic acid (cPA; 1-acyl-sn-glycerol-2,3-cyclic phosphate) is an analog of the growth factor-like phospholipid mediator lysophosphatidic acid (LPA). As brain tissue is the richest source of cPA we tested its effects on hippocampal neurons from day 16/17 embryonic rat cultured in a serum-free medium. Nanomolar concentrations of cPA elicited a neurotrophic effect and promoted neurite outgrowth that exceeded that of 50 ng/mL nerve growth factor (NGF). Pertussis toxin, the LPA1/LPA3 receptor-selective antagonist dioctylglycerol pyrophosphate, the myristoylated inhibitory pseudosubstrate peptide of protein kinase A (PKI), Wortmannin and PD98059 abolished the neurite-promoting effect. cPA elicited a sustained activation of extracellular signal-related kinases (ERK) 1/2 and Akt. Clostridium difficile toxin B, an inhibitor of the Rho family of GTPases, reduced cPA-induced enhancement of neurite outgrowth. In B5P cells, a clonal cell line of PC12 cells overexpressing tyrosine kinase NGF receptor (TrkA), cPA elicited transphosphorylation of TrkA. cPA-elicited ERK activation was blocked by K252a and PKI. These results suggest that cPA mimics the effects of, and activates signaling pathways similar to, the neurotrophin NGF in cultured embryonic hippocampal neurons and B5P cells.
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PMID:Cyclic phosphatidic acid elicits neurotrophin-like actions in embryonic hippocampal neurons. 1462 7

We have recently shown that nerve growth factor (NGF) induces the phosphorylation of the microtubule-associated protein 1B (MAP1B) by activating the serine/threonine kinase glycogen synthase kinase 3beta (GSK3beta) in a spatio-temporal pattern in PC12 cells that correlates tightly with neurite growth. PC12 cells express two types of membrane receptor for NGF: TrkA receptors and p75NTR receptors, and it was not clear from our studies which receptor was responsible. We show here that brain-derived neurotrophic factor, which activates p75NTR but not TrkA receptors, does not stimulate GSK3beta phosphorylation of MAP1B in PC12 cells. Similarly, NGF fails to activate GSK3beta phosphorylation of MAP1B in PC12 cells that lack TrkA receptors but express p75NTR receptors (PC12 nnr). Chick ciliary ganglion neurons in culture lack TrkA receptors but express p75NTR and also fail to show NGF-dependent GSK3beta phosphorylation of MAP1B, whereas in rat superior cervical ganglion neurons in culture, NGF activation of TrkA receptors elicits GSK3beta phosphorylation of MAP1B. Finally, inhibition of TrkA receptor tyrosine kinase activity in PC12 cells and superior cervical ganglion neurons with K252a potently and dose-dependently inhibits neurite elongation while concomitantly blocking GSK3beta phosphorylation of MAP1B. These results suggest that the activation of GSK3beta by NGF is mediated through the TrkA tyrosine kinase receptor and not through p75NTR receptors.
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PMID:NGF activates the phosphorylation of MAP1B by GSK3beta through the TrkA receptor and not the p75(NTR) receptor. 1462 24

The underlying mechanism for nerve growth factor (NGF) evoked pain and long-lasting mechanical hyperalgesia remains poorly understood. Using intrathecal antisense against the NGF receptor, receptor tyrosine kinase (TrkA), we found NGF to act at the primary afferent nociceptor directly in the Sprague-Dawley rat. Inhibitors of the three major pathways for TrkA receptor signalling, extracellular signal-related kinase (ERK)/mitogen-activated protein kinase kinase (MEK) (ERK/MEK), phosphatidylinositol 3-kinase (PI3K), and phospholipase Cgamma (PLCgamma) all attenuate NGF-induced hyperalgesia. Although inhibitors of kinases downstream of PI3K and PLCgamma[glycogen synthetase kinase 3 (GSK3), calmodulin-dependent protein kinase II (CAMII-K) or protein kinase C (PKC)] do not reduce mechanical hyperalgesia, hyperalgesia induced by activation of PI3K was blocked by ERK/MEK inhibitors, suggesting cross-talk from the PI3K to the ERK/MEK signalling pathway. As integrins have been shown to modulate epinephrine and prostaglandin E(2)-induced hyperalgesia, we also evaluated a role for integrins in NGF-induced mechanical hyperalgesia using beta(1)-integrin-specific antisense or antibodies.
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PMID:Primary afferent nociceptor mechanisms mediating NGF-induced mechanical hyperalgesia. 1602 76


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