Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0027819 (neuroblastoma)
 27,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mitogen-activated protein (MAP) kinase phosphorylates tau in cell-free analyses, but whether or not it does so within intact cells remains controversial. In the present study, microinjection of MAP kinase into SH-SY-5Y human neuroblastoma cells increased tau immunoreactivity toward the phosphodependent antibodies PHF-1 and AT-8. In contrast, treatment with a specific inhibitor of MAP kinase (PD98059) did not diminish "basal" levels of these immunoreactivities in otherwise untreated cells. These findings indicate that hyperactivation of MAP kinase increases phospho-tau levels within cells, despite that MAP kinase apparently does not substantially influence intracellular tau phosphorylation under normal conditions. These findings underscore that results obtained following inhibition of kinase activities do not necessarily provide an indication of the consequences accompanying hyperactivation of that same kinase. Several studies conducted in cell-free systems indicate that exposure of tau to multiple kinases can have synergistic effects on the nature and extent of tau phosphorylation. We therefore examined whether or not such effects could be demonstrated within these cells. Site-specific phospho-tau immunoreactivity was increased in additive and synergistic manners by treatment of injected cells with TPA (which activates PKC), calcium ionophore (which activates calcium-dependent kinases), and wortmannin (which inhibits PIP3 kinase). Alteration in total tau levels was insufficient to account for the full extent of the increase in phospho-tau immunoreactivity. These additional results indicate that multiple kinase activities modulate the influence of MAP kinase on tau within intact cells.
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PMID:Hyperactivation of mitogen-activated protein kinase increases phospho-tau immunoreactivity within human neuroblastoma: additive and synergistic influence of alteration of additional kinase activities. 1008 8

Chronic activation of the mu-opioid receptor (MOR1TAG) results in the loss of agonist response that has been attributed to desensitization and down-regulation of the receptor. It has been suggested that opioid receptor phosphorylation is the mechanism by which this desensitization and down-regulation occurs. When MOR1TAG was stably expressed in both neuroblastoma neuro2A and human embryonic kidney HEK293 cells, the opioid agonist [D-Ala2,MePhe4, Gly5-ol]enkephalin (DAMGO) induced a time- and concentration-dependent phosphorylation of the receptor, in both cell lines, that could be reversed by the antagonist naloxone. Protein kinase C can phosphorylate the receptor, but is not involved in DAMGO-induced MOR1TAG phosphorylation. The rapid rate of receptor phosphorylation, occurring within minutes, did not correlate with the rate of the loss of agonist-mediated inhibition of adenylyl cyclase, which occurs in hours. This lack of correlation between receptor phosphorylation and the loss of response was further demonstrated when receptor phosphorylation was increased by either calyculin A or overexpression of the G-protein receptor kinases. Calyculin A increased the magnitude of MOR1TAG phosphorylation without altering the DAMGO-induced loss of the adenylyl cyclase response. Similarly, when mu- and delta-opioid (DOR1TAG) receptors were expressed in the same system, overexpression of beta-adrenergic receptor kinase 2 elevated agonist-induced phosphorylation for both receptors. However, in the same cell lines under the same conditions, overexpression of beta-adrenergic receptor kinase 2 and beta-arrestin 2 accelerated the rate of DPDPE- but not DAMGO-induced receptor desensitization. Thus, these data show that phosphorylation of MOR1TAG is not an obligatory event for the DAMGO-induced loss in the adenylyl cyclase regulation by the receptor.
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PMID:The absence of a direct correlation between the loss of [D-Ala2, MePhe4,Gly5-ol]Enkephalin inhibition of adenylyl cyclase activity and agonist-induced mu-opioid receptor phosphorylation. 1009 93

We investigated the ability of the antidementia agents, nicergoline, aniracetam and hydergine to stimulate PKC mediated alpha-secretase amyloid precursor protein (APP) processing in cultured human neuroblastoma SH-SY5Y cells. Western immunoblotting of cell conditioned media using the Mabs 22C11 and 6E10 revealed the presence of 2 bands with molecular mass of 90 and 120 kDa, corresponding to possible alternatively glycosylated forms of secreted APP (APPs). Short-term (30 min and 2 h) treatment of cells with nicergoline gave an increased intensity of both bands, compared to non-treated cells. Maximal nicergoline effects, of the order of 150-200% over basal APPs release, were seen at concentrations between 1 and 10 microM. Under the same condition, 1 microM PdBu, used as a positive control, gave 500-1000% increases of basal APPs release. In contrast, aniracetam and hydergine, did not show any effect on APPs secretion. 2 h treatment with nicergoline had no effect on cellular full-length APP levels, as determined by immunoblotting of cell extracts with 22C11 and CT15 antibodies. Immunoblotting with PKC isoform specific antibodies of soluble and membrane fractions prepared from 2 h treated cells, showed that nicergoline (50 microM) and PdBu (1 microM) both induced translocation of PKC alpha, gamma and epsilon, but not PKC beta. The involvement of PKC in mediating nicergoline stimulated APPs release was also studied using specific inhibitors. 1 microM calphostin C, a broad range PKC inhibitor, significantly reduced both PdBu (1 microM) and nicergoline (10 microM) induced APPs release. In contrast, Go6976 (1 microM), a selective PKC alpha and beta1 inhibitor, as well as the cAMP-dependent protein kinase inhibitor, H89 (1 microM) were without effect. These results indicate that nicergoline can modulate alpha-secretase APP processing by a PKC dependent mechanism that is likely to involve the gamma and epsilon isoforms of this enzyme.
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PMID:Nicergoline stimulates protein kinase C mediated alpha-secretase processing of the amyloid precursor protein in cultured human neuroblastoma SH-SY5Y cells. 1048 51

The role of the phosphatidylinositol 3-kinase (PI3K) pathway in the hyperphosphorylation of tau was investigated in SY5Y human neuroblastoma cells. Wortmannin, an inhibitor of PI3K, induced transient (after 1 h) activation of glycogen synthase kinase-3 (GSK-3), hyperphosphorylation of tau and dose-dependent cytotoxicity. However, continuous inactivation of protein kinase (PK) B was observed from 1 to 24 h, suggesting the involvement of protein kinase(s) other than PKB in the phosphorylation and inactivation of GSK-3 after 3 h. In cells treated with wortmannin, PKC delta fragments were observed, and the PKC activity increased after 3 h, whereas treatment of cells with z-DEVD-fmk, an inhibitor of caspase 3, also inhibited fragmentation of PKC delta and induced continuous activation of GSK-3. It is suggested that fragmentation of PKC delta during the process of apoptosis results in the phosphorylation and inactivation of GSK-3 and consequently inhibition of the phosphorylation of tau.
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PMID:Inactivation of glycogen synthase kinase-3 by protein kinase C delta: implications for regulation of tau phosphorylation. 1070 67

Uridine metabolism has an important role in the physiopathology of the nervous system. In this paper, we have explored the effects of exogenous uridine on LAN-5 human neuroblastoma cells. Cells were exposed to uridine for 4 days and cell proliferation, neurite outgrowth, and 160 kDa neurofilament (NF) expression were the parameters measured. Our results showed that 10 microg/ml uridine decreased cell proliferation, this effect being associated with an increase in cell differentiation, as evidenced by neurite outgrowth and NF expression. These effects can be prevented by dipyridamole (10 microM), an inhibitor of nucleotides and nucleosides uptake. In the literature, neuroblastoma cells differentiation has been demonstrated to involve Protein Kinase C epsilon (PKCepsilon). After treatment with uridine, we observed in LAN-5 cells an increase in PKCepsilon protein level. This increase was inhibited by dipyridamole. Moreover, the increase of neurite outgrowth induced by uridine was inhibited by treatment with bisindolylmaleimide I (GF109203X), an inhibitor of PKC. Our data suggest that PKCepsilon is involved in uridine-induced cell differentiation in human neuroblastoma cells.
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PMID:Uridine induces differentiation in human neuroblastoma cells via protein kinase C epsilon. 1087 93

Regulation of phospholipase D (PLD) activity participating in signal transduction involves complex interactions with small G-proteins (ARF, Rho) and protein kinase C isoforms (PKCalpha). In SK-N-MC human neuroblastoma cells, phorbol ester (TPA) activation of PLD was enhanced by overexpressing myristoylated alanine-rich C kinase substrate (MARCKS). To study MARCKS interactions with PLD, we investigated PLD isoform expression and activation by TPA and GTPgammaS in intact and digitonin-permeabilized clones transfected with MARCKS (M22). PLD2 was in both cytosol and membrane fractions while PLD1 was primarily membrane-associated in both vector control and M22 cells; location or quantities were unaltered by TPA treatment. TPA-stimulated PLD activity was higher in both intact and digitonin-permeabilized M22 cells than in vector controls. In contrast, GTPgammaS-stimulated PLD activity was independent of MARCKS expression but was additive with MARCKS-PKC-dependent activation in permeabilized cells. Combinations of PKC inhibition and down-regulation in intact and permeabilized (with GTPgammaS present) cells indicated that a PKC-mediated phosphorylation event was necessary in intact cells without access to GTPgammaS, stimulation of PLD mediated by GTPgammaS was independent of PKC, and PLD activation by PKC in permeabilized cells was kinase-independent. Western blot analysis showed that MARCKS, PKCalpha, PLD1 and PLD2 were present in a detergent-insoluble fraction (DIF); GTPgammaS increased recovery of PLD2 in DIF. Disruption of cholesterol-rich DIFs with digitonin, cyclodextrin or filipin potentiated activation of PLD by TPA. Our studies suggest that activation of PLD by PKC requires MARCKS and can involve both phosphorylation-independent and -dependent processes. As PLD activation by GTPgammaS is PKC-MARCKS-independent, MARCKS may provide a fine tuning component in conjunction with G-protein-mediated mechanisms for regulation of PLD.
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PMID:Activation of phospholipase D by PKC and GTPgammaS in human neuroblastoma cells overexpressing MARCKS. 1101 70

Neuroblastoma LAN-5 cells exposed to retinoic acid cease to multiply and extend neurite outgrowths acquiring a neuronal phenotype. We now report that protein kinase C-theta; (PKC-theta;) isozyme is involved in this differentiation process due to the following findings: (i) PKC-theta; is expressed by LAN-5 cells as a nuclear and perinuclear protein; (ii) cell stimulation with retinoic acid promotes in a large increase in the expression level of the kinase and its intracellular redistribution; and (iii) a PKC-theta; antisense oligonucleotide reduces at the same time the expression level of the kinase and the cell response to retinoic acid. Altogether these data are consistent with a specific role played by PKC-theta; in the differentiation program of neuronal cells.
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PMID:Human neuroblastoma cell differentiation requires protein kinase C-theta. 1111 30

To investigate mechanisms of neurite outgrowth, murine Neuro-2a neuroblastoma cells were exposed to ganglioside GM1 in the presence or absence of specific protein kinase inhibitors. Isoquinolinesulfonamide (H-89), an inhibitor of cyclic AMP dependent protein kinase A (PKA), and bisindolylmaleimide I (BIM), which inhibits protein kinase C, each stimulated neurite outgrowth in a dose-dependent manner in the absence of exogenous GM1. Minimally effective (threshold) concentrations of H-89 or BIM potentiated outgrowth when they were used in combination with GM1. To search for a shared component in the mechanisms of GM1, H-89 and BIM, phosphorylation of ERK1/2 was examined. Inhibition of the activation of extracellular signal regulated kinases (ERK1/2) by U0126, prevented neuritogenesis of Neuro-2a by all the three agents. Pretreatment of serum-depleted Neuro-2a cultures with GM1 or BIM enhanced ERK1/2 phosphorylation when the serum level was restored to 10%. In contrast, H-89 did not alter the serum-mediated response. In cells exposed to GM1 or BIM without additional serum, a transitory decrease in ERK phosphorylation occurred. These data suggest that GM1 influences two neuritogenic pathways, one modulated by PKC and the other regulated by PKA. Therefore, GM1 may have the potential to stimulate alternate pathways resulting in outgrowth.
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PMID:Promotion of neurite outgrowth by protein kinase inhibitors and ganglioside GM1 in neuroblastoma cells involves MAP kinase ERK1/2. 1115 49

The human neuroblastoma cell line SH-SY5Y/TrkA differentiates in vitro and acquires a sympathetic phenotype in response to phorbolester (activator of protein kinase C, PKC) in the presence of serum or growth factors, or nerve growth factor (NGF). We have now investigated to what extent phorbolester and NGF cause activation of Ras and Raf-1 and the involvement of PKC in this response in differentiating SH-SY5Y/TrkA cells. NGF stimulated increased accumulation of Ras-GTP and a threefold activation of Raf-1. In contrast, 12-O-tetradecanoylphorbol-13-acetate (TPA) had no effect on the amount of Ras-GTP but led to a smaller activation of Raf-1. NGF caused a limited increase in phosphorylation of Raf-1 compared with TPA, and NGF-induced Raf activity was independent of PKC. Analysis of phosphorylation of the endogenous PKC substrate myristoylated alanine-rich C-kinase substrate (MARCKS), and of subcellular distribution of PKC-alpha, -delta, and -epsilon revealed that NGF only caused a very small activation of PKC in SH-SY5Y/TrkA cells. The results identify Raf-1 as a target for both TPA- and NGF-induced signals in differentiating SH-SY5Y/TrkA cells and demonstrate that signalling to Raf-1 was mediated via distinct mechanisms.
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PMID:Activation of Ras, Raf-1 and protein kinase C in differentiating human neuroblastoma cells after treatment with phorbolester and NGF. 1125 53

SH-SY5Y neuroblastoma cells are a well-characterized model for studying the induction of neuronal differentiation. TPA treatment of these cells induces cytoskeletal rearrangements that ultimately result in neurite extension. However, the signaling pathways that precede these changes are poorly understood. Other investigators have shown that TPA treatment of SH-SY5Y cells results in increased tyrosine phosphorylation of cytoskeletal-associated proteins, including the adapter protein Cas. In this report, we examine the events upstream and downstream of Cas phosphorylation. We show that TPA treatment induces the PKC-dependent association of tyrosine-phosphorylated Cas with Crk. The activity of two protein tyrosine kinases, Src and FAK, was shown to be necessary and sufficient for TPA-induced Cas phosphorylation. We propose that the PKC-dependent phosphorylation of Cas by Src and FAK promotes the establishment of Cas-Crk complexes and that these interactions may play an important role in regulating the actin cytoskeleton during neuronal differentiation.
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PMID:PKC-dependent activation of FAK and src induces tyrosine phosphorylation of Cas and formation of Cas-Crk complexes. 1126 86


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