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

Measles virus (MV) persistence in brain cells has broad effects on different cellular functions. We have previously shown that NS20Y clone, originally derived from C1300 neuroblastoma cells, persistently infected with MV (NS20Y/MS), displays constitutively elevated levels of c-fos and PKC mRNAs, implying MV-mediated effects on transcriptional regulation. Nonetheless, the mode by which virus affects the transcriptional machinery still remains obscure. In order to define this phenomenon, we studied the binding properties of major transcription factors (AP-1 and NFkappaB) in NS20Y/MS cells. Using electrophoretic mobility shift approach (EMSA) with the appropriate oligonucleotide probes, we have found that the persistent MV infection does not affect NFkappaB binding, while the AP-1 binding was significantly decreased. Similar inhibition was not observed in NS20Y cells acutely infected with MV. Anti-measles antibody-mediated restriction of viral gene expression restored AP-1 binding, thus suggesting that measles virus proteins may affect the components of the host transcriptional machinery.
 ...
PMID:The effects of measles virus persistent infection on AP-1 transcription factor binding in neuroblastoma cells. 923 27

SH-SY-5Y human neuroblastoma cells were treated with 22 microM of a synthetic peptide corresponding to amino acid residues 25-35 of beta-amyloid (betaA) or 3 microM calcium ionophore A23187 in culture medium containing 1.8 mM extracellular calcium. Both agents increased tau immunoreactivity towards antibodies (PHF-1, ALZ-50) that recognize epitopes common with paired helical filaments (PHFs) and towards an antibody (5E2) that recognized a phosphate-independent tau epitope. However, only ionophore increased immunoreactivity with an additional phosphate-dependent antibody (AT-8) that recognized an epitope of tau when phosphorylated, and induced a corresponding decrease in immunoreactivity towards an additional antibody (Tau-1) that recognizes the same site when that site is not phosphorylated. Moreover, the ionophore-mediated increase in PHF-1 was blocked by EGTA, by the calpain inhibitor calpeptin and by the PKC inhibitor H7, while that evoked by betaA treatment was not inhibited by any of these treatments. Since ionophore-mediated calpain activation induces proteolytic PKC activation, we further examined the influence of PKC inhibition on betaA and ionophore-mediated PHF-1 induction. Antisense oligonucleotide-mediated downregulation of PKCepsilon in a stable transfectant SH-SY-5Y subclone diminished the ionophore-mediated, but not the betaA-mediated, increase in PHF-1 immunoreactivity. These data indicate specific differences in the intracellular cascade of events invoked by betaA and ionophore A23187. Moreover, although betaA invoked calcium influx in these cells, our findings further suggest that the induction of tau hyperphosphorylation by betaA may not be due to calcium influx.
 ...
PMID:Beta-amyloid and ionophore A23187 evoke tau hyperphosphorylation by distinct intracellular pathways: differential involvement of the calpain/protein kinase C system. 933 63

Protein kinase C regulates mRNAs encoding several G protein-linked receptors but its role in adenosine A2a receptor expression is not known. We tested the hypothesis that protein kinase C activated by tetradecanoyl phorbol acetate (TPA) regulates adenosine A2a receptor mRNA levels. SH-SY5Y human neuroblastoma cells express adenosine receptors which positively couple to adenylyl cyclase with a pharmacologic profile expected of the A2a subtype. Northern blotting demonstrated an adenosine A2a receptor mRNA species of similar molecular size in SH-SY5Y cells and in human brain. TPA increased adenosine A2a receptor mRNA in a dose- and time-dependent fashion. Transcription or translation inhibition prevented increases in adenosine A2a receptor mRNA. Bisindolylmaleimide blocked TPA effects. Adenosine A2a receptor mRNA stability was unchanged by TPA. This study identifies a human neuroblastoma cell line expressing functional adenosine A2a receptors. Protein kinase C activation appears to enhance transcription of the adenosine A2a receptor gene.
 ...
PMID:Protein kinase C regulates adenosine A2a receptor mRNA expression in SH-SY5Y cells. 938 56

Protein kinase C (PKC) activation after treatment of human neuroblastoma SK-N-BE(2)C cells with phorbol 12-myristate 13-acetate (PMA) was found to enhance transcription of the human dopamine beta-hydroxylase (DBH) in those cells. To identify which cis-acting element is responsive to the PMA treatment during DBH gene expression, we employed transient transfection assays with serially deleted constructs of the human DBH gene's 5' upstream region fused to the chloramphenicol acetyltransferase (CAT) gene. Treatment of transfected cells with PMA resulted in an approximate threefold increase in CAT expression for all deletion constructs ranging from -978 bp to -262 bp, while the enhancement did not occur with a construct shortened to -114 bp. The region between -262 and -114 bp from the initiation site of transcription contains several cis-regulatory elements including a cyclic AMP response element (CRE) and putative AP1 and YY1 sequences. Site-directed mutagenesis of those cis-acting elements were performed to identify which of the elements mediated the PMA-induced transcriptional enhancement. Substitution of bases in the putative AP1 site containing in part a putative YY1 sequence did not effect the PMA inducibility. However, specific mutations in the CRE sequence abolished the PMA-inducible effect. Changing the CRE sequence into an authentic AP1 sequence (TGACGTCC --> TGACTCA) did not affect the PMA inducibility, suggesting that AP1 factors might interact with the new AP1 site upon PKC activation. A specific PKC inhibitor, GF109203X, completely inhibited the stimulatory effect of PMA on the expression of the human DBH gene. PMA induced an increase in the DBH mRNA level as detected by Northern blot analysis. Gel retardation showed that the binding of nuclear factors to CRE, putative YY1, and AP1 was sequence specific. Our data suggest that the enhancement of the human DBH gene expression by PMA treatment is mediated by the CRE motif in the 5' upstream region of the gene, and occurs via a PKC-dependent pathway.
 ...
PMID:A protein kinase C-activating phorbol ester enhances transcription of the human DBH gene through a cyclic AMP response element in SK-N-BE(2)C cells. 942 17

Measles virus (MV) is among the infectious agents displaying a propensity for establishing persistent infections of the CNS. It is assumed that continuous presence of MV defective particles or viral genome in persistently infected cells may influence host cellular processes and perturb biochemical signal transduction pathways operating in linkage to various cell surface receptors. PKC expression in a MV persistently infected neuroblastoma cell line (NS20Y/MS) was investigated. The relative levels of PKC isoenzymes were determined by Western blot analysis. We found that protein levels of PKCalpha, epsilon and zeta, but not PKCdelta, were increased in NS20Y/MS cells. PKCbeta, gamma and eta were undetectable. Treatment of NS20Y/MS cells with anti-MV Abs, which downregulated MV protein synthesis, also reduced PKCalpha expression to the basal level observed in the uninfected NS20Y cells. Our results suggest that a persistent MV infection has specific effects on the expression of certain PKC isoenzymes. We postulate that the MV-associated neurologic changes may reflect virus induced changes in biochemical signaling pathways and that these effects are likely to be regulated by the host's anti-viral humoral immune response.
 ...
PMID:Persistent measles virus infection of murine neuroblastoma cells differentially affects the expression of PKC individual isoenzymes. 948 88

Human cocaine users exhibit increased striatal [3H]WIN35428 binding to the dopamine transporter (DAT). However, the nature of the changes induced in the DAT are complex and may not result from a simple increase in number of DAT molecules. To better understand the regulation of DAT inhibitor binding sites and their relationship to the overall process of dopamine uptake, a neuronal model system expressing the human DAT has been developed. Initial experiments were attempted with native dopaminergic neurons so as to allow examination of DAT interactions with vesicular release and storage mechanisms. Dissociated fetal rat mesencephalic neurons, of various ages and mixtures with target cells, were grown to confluence. However, [3H]WIN35428 binding was of low affinity at all levels of maturity. Following this, a simpler model was assessed, using DAT cDNA transfected into neuroblastoma-derived Neuro2A cells. Initially, no specific and little non-specific [3H]WIN35428 or [3H]paroxetine binding was found in non-transfected cells. After transfection with the human DAT inserted in the pcDNA vector, both DAT binding and dopamine uptake were significantly and stably present. Treatment with (-)cocaine, 10-6 M for 24 h, increased DAT binding and uptake, which did not occur in parallel COS-7 experiments. Other experiments with Neuro2A cells also found that dopamine uptake was down-regulated by treatment with a PKC activator. These results suggest that the transfected Neuro2A neurons should be useful for ongoing experiments examining the regulation of the DAT by assorted treatments.
 ...
PMID:Expression and regulation of the human dopamine transporter in a neuronal cell line. 972 82

Norepinephrine (NE) transporters (NETs) found in the neuronal plasma membrane mediate the removal of NE from the extracellular space, limiting the activation of adrenoceptors at noradrenergic synapses. Our previous studies with the noradrenergic neuroblastoma SK-N-SH have revealed a muscarinic receptor-triggered regulation of NET surface density and transport capacity, mediated in part by protein kinase C activation. Low abundance of NET proteins in this native cell model, however, preclude direct confirmation of altered trafficking of NET proteins. In our study, we monitored the activity and surface distribution of human NET proteins in transient and stably-transfected cell lines after application of kinase activators and inhibitors. Using hNET stably transfected HEK-293 and LLC-PK1 cells, as well as transiently transfected COS-7 cells, we demonstrate that PKC-activating phorbol esters, beta-PMA or beta-PDBu selectively diminish l-NE transport capacity (Vmax) with little change in NE Km. Effects of phorbol esters are rapid, stereospecific and blocked by protein kinase C inhibitors, staurosporine and bisindolylmaleimide I. As in SK-N-SH cells, beta-PMA induces a reduction in intact cell [3H]nisoxetine binding sites with no change in nisoxetine Kd or total membrane NET density. Cell-surface biotinylation and confocal immunofluorescence techniques confirm that protein kinase C-dependent reductions in NE transport capacity and whole-cell antagonist binding density are accompanied by reductions in cell-surface human NET protein expression. Together these findings argue for kinase-modulated protein trafficking as a potential route for acute regulation of antidepressant-sensitive NE clearance.
 ...
PMID:Acute regulation of norepinephrine transport: II. PKC-modulated surface expression of human norepinephrine transporter proteins. 980 5

Agonist-induced down-regulation of opioid receptors appears to require the phosphorylation of the receptor protein. However, the identities of the specific protein kinases that perform this task remain uncertain. Protein kinase C (PKC) has been shown to catalyze the phosphorylation of several G protein-coupled receptors and potentiate their desensitization toward agonists. However, it is unknown whether opioid receptor agonists induce PKC activation under physiological conditions. Using cultured SH-SY5Y neuroblastoma cells, which naturally express mu- and delta-opioid receptors, we investigated whether mu-opioid receptor agonists can activate PKC by measuring enzyme translocation to the membrane fraction. PKC translocation and opioid receptor densities were simultaneously measured by 3H-phorbol ester and [3H]diprenorphine binding, respectively, to correlate alterations in PKC localization with changes in receptor binding sites. We observed that mu-opioid agonists have a dual effect on membrane PKC density depending on the period of drug exposure. Exposure for 2-6 h to [D-Ala2,N-Me-Phe4,Gly-ol]enkephalin or morphine promotes the translocation of PKC from the cytosol to the plasma membrane. Longer periods of opioid exposure (>12 h) produce a decrease in membrane-bound PKC density to a level well below basal. A significant decrease in [3H]diprenorphine binding sites is first observed at 2 h and continues to decline through the last time point measured (48 h). The opioid receptor antagonist naloxone attenuated both opioid-mediated PKC translocation and receptor down-regulation. These results demonstrate that opioids are capable of activating PKC, as evidenced by enhanced translocation of the enzyme to the cell membrane, and this finding suggests that PKC may have a physiological role in opioid receptor plasticity.
 ...
PMID:Role of protein kinase C (PKC) in agonist-induced mu-opioid receptor down-regulation: I. PKC translocation to the membrane of SH-SY5Y neuroblastoma cells is induced by mu-opioid agonists. 993 Jul 30

Phosphorylation of specific amino acid residues is believed to be crucial for the agonist-induced regulation of several G protein-coupled receptors. This is especially true for the three types of opioid receptors (mu, delta, and kappa), which contain consensus sites for phosphorylation by numerous protein kinases. Protein kinase C (PKC) has been shown to catalyze the in vitro phosphorylation of mu- and delta-opioid receptors and to potentiate agonist-induced receptor desensitization. In this series of experiments, we continue our investigation of how opioid-activated PKC contributes to homologous receptor down-regulation and then expand our focus to include the exploration of the mechanism(s) by which mu-opioids produce PKC translocation in SH-SY5Y neuroblastoma cells. [D-Ala2,N-Me-Phe4,Gly-ol]enkephalin (DAMGO)-induced PKC translocation follows a time-dependent and biphasic pattern beginning 2 h after opioid addition, when a pronounced translocation of PKC to the plasma membrane occurs. When opioid exposure is lengthened to >12 h, both cytosolic and particulate PKC levels drop significantly below those of control-treated cells in a process we termed "reverse translocation." The opioid receptor antagonist naloxone, the PKC inhibitor chelerythrine, and the L-type calcium channel antagonist nimodipine attenuated opioid-mediated effects on PKC and mu-receptor down-regulation, suggesting that this is a process partially regulated by Ca2+-dependent PKC isoforms. However, chronic exposure to phorbol ester, which depletes the cells of diacylglycerol (DAG) and Ca2+-sensitive PKC isoforms, before DAMGO exposure, had no effect on opioid receptor down-regulation. In addition to expressing conventional (PKC-alpha) and novel (PKC-epsilon) isoforms, SH-SY5Y cells also contain a DAG- and Ca2+-independent, atypical PKC isozyme (PKC-zeta), which does not decrease in expression after prolonged DAMGO or phorbol ester treatment. This led us to investigate whether PKC-zeta is similarly sensitive to activation by mu-opioids. PKC-zeta translocates from the cytosol to the membrane with kinetics similar to those of PKC-alpha and epsilon in response to DAMGO but does not undergo reverse translocation after longer exposure times. Our evidence suggests that direct PKC activation by mu-opioid agonists is involved in the processes that result in mu-receptor down-regulation in human neuroblastoma cells and that conventional, novel, and atypical PKC isozymes are involved.
 ...
PMID:Role of protein kinase C (PKC) in agonist-induced mu-opioid receptor down-regulation: II. Activation and involvement of the alpha, epsilon, and zeta isoforms of PKC. 993 Jul 31

Regulatory interactions among individual receptor-coupled signal transduction systems are critically important for establishing cellular responses in the face of multiple stimuli. In this study, potential regulatory interactions between signal transduction systems activated by growth factor receptors and by G-protein-coupled receptors were examined using human neuroblastoma SH-SY5Y cells which express endogenous epidermal growth factor (EGF) and muscarinic M3 receptors. Activation of muscarinic receptors with carbachol was found to inhibit EGF-induced signaling, including tyrosine phosphorylation of the adaptor protein Cbl and of the EGF receptor, and complex formation between Shc proteins and the EGF receptor and Grb2. Protein kinase C, which is activated by muscarinic M3 receptors, mediated this inhibitory cross-talk. Activation of EGF receptors was found to inhibit muscarinic receptor-induced tyrosine phosphorylation of focal adhesion kinase and paxillin. Reactive oxygen species, which are formed as components of the EGF signaling cascade, mediated this inhibitory cross-talk. These mutual inhibitory interactions demonstrate novel mechanisms for neuronal integration of multiple signals generated by activation of receptors by neurotransmitters and growth factors.
 ...
PMID:Muscarinic M3 and epidermal growth factor receptors activate mutually inhibitory signaling cascades in human neuroblastoma SH-SY5Y cells. 1004 86


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>