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)

Stimulation of soluble guanylyl cyclase in rat fetal lung fibroblasts (RFL-6 cells) was used as a sensitive assay for endothelium-derived relaxing factor/nitric oxide (EDRF/NO) formation. Intact N1E-115 cells released an EDRF/NO-like material that enhanced cyclic GMP levels in RFL-6 cells. The synthesis of this substance could be stimulated with the receptor agonist neurotensin (10 microM) or by addition of the EDRF/NO substrate L-arginine (100 microM). In Ca2(+)-free Locke's solution, stimulation of EDRF/NO production by both neurotensin and L-arginine was abolished. The EDRF/NO-synthesizing activity was localized in the cytosol of N1E-115 cells. The activity was lost after boiling and it was highly sensitive to Ca2+ with the major increase in activity occurring between 100 and 500 nM Ca2+. L-Arginine and NADPH were required for maximal synthesis of EDRF/NO by the enzyme(s). The synthesis of EDRF/NO was inhibited by the following antagonists of calmodulin-regulated functions (with the approximate IC50 values given in parentheses): calmidazolium (7 microM), trifluoperazine (10 microM), fendiline (80 microM), W-7 (N-[6-aminohexyl]-5-chloro-1-naphthalenesulfonamide) (120 microM), and compound 48/80 (3 micrograms/ml). The EDRF/NO-synthesizing activity was partially purified from N1E-115 cytosol by DE 52 anion exchange chromatography. The activity was eluted with 0.1 M KCl. The enzyme(s) showed very little activity in the presence of L-arginine (100 microM) and NADPH (100 microM), but the activity could be fully restored by addition of exogenous calmodulin (EC50, approximately 2 units/ml). At 0.3 M KCl, a fraction eluted from the DE 52 column that was also able to fully restore the EDRF/NO-synthesizing activity. Thus, this fraction is likely to contain the endogenous Ca2(+)-binding protein. It is concluded that the activity of the EDRF/NO-synthesizing enzyme(s) in N1E-115 neuroblastoma cells is regulated by Ca2+ and calmodulin.
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PMID:Hormone-induced biosynthesis of endothelium-derived relaxing factor/nitric oxide-like material in N1E-115 neuroblastoma cells requires calcium and calmodulin. 237 Aug 55

The structures of the genes encoding the alpha(1) and beta(1) subunits of murine soluble guanylyl cyclase (sGC) were determined. Full-length cDNAs isolated from mouse lungs encoding the alpha(1) (2.5 kb) and beta(1) (3.3 kb) subunits are presented in this report. The alpha(1) sGC gene is approximately 26.4 kb and contains nine exons, whereas the beta(1) sGC gene spans 22 kb and consists of 14 exons. The positions of exon/intron boundaries and the sizes of introns for both genes are described. Comparison of mouse genomic organization with the Human Genome Database predicted the exon/intron boundaries of the human genes and revealed that human and mouse alpha1 and beta1 sGC genes have similar structures. Both mouse genes are localized on the third chromosome, band 3E3-F1, and are separated by a fragment that is 2% of the chromosomal length. The 5' untranscribed regions of alpha(1) and beta(1) subunit genes were subcloned into luciferase reporter constructs, and the functional analysis of promoter activity was performed in murine neuroblastoma N1E-115 cells. Our results indicate that the 5' untranscribed regions for both genes possess independent promoter activities and, together with the data on chromosomal localization, suggest independent regulation of both genes.
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PMID:Genomic organization of alpha1 and beta1 subunits of the mammalian soluble guanylyl cyclase genes. 1098 16

The transcription factor cAMP-response element-binding protein (CREB) mediates survival in many cells, including neurons. Recently, death of cerebellar granule neurons due to nitric oxide (NO) deprivation was shown to be accompanied by down-regulation of CREB activity (). We now provide evidence that overproduction of endogenous NO or supplementation with exogenous NO renders SK-N-BE human neuroblastoma cells more resistant to apoptosis induced by serum deprivation. Parental cells underwent apoptosis after 24 h of serum deprivation, an outcome largely absent in clones overexpressing human neuronal nitric oxide synthase (nNOS). This protective effect was reversed by the inhibition of NOS itself or soluble guanylyl cyclase, pointing at cGMP as an intermediate effector of NO-mediated rescue. A slow-releasing NO donor protected parental cells to a significant extent, thus confirming the survival effect of NO. The impaired viability of serum-deprived parental cells was accompanied by a strong decrease of CREB phosphorylation and transcriptional activity, effects significantly attenuated in nNOS-overexpressing clones. To confirm the role of CREB in survival, the ectopic expression of CREB and/or protein kinase A largely counteracted serum deprivation-induced cell death of SK-N-BE cells, whereas transfection with a CREB negative mutant was ineffective. These experiments indicate that CREB activity is an important step for NO-mediated survival in neuronal cells.
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PMID:Nitric oxide protects neuroblastoma cells from apoptosis induced by serum deprivation through cAMP-response element-binding protein (CREB) activation. 3214 54

Nitric oxide (NO) contributes to cellular degeneration in various disorders, particularly in the nervous system. NO targets cell proteins such as soluble guanylyl cyclase, but its detrimental effects are generally attributed to its reaction product with superoxide, peroxynitrite. To understand the mechanisms of NO-induced cell stress, we studied the effects of the NO donors diethylenetriamine and spermine NONOate and the peroxynitrite donor 5-amino-3-(4-morpholinyl)-1,2,3-oxadiazolium chloride (SIN-1) in SH-SY5Y and NG108-15 neuroblastoma cells. All three compounds induced a dose- and time-dependent decrease in viable cells, which was not blocked by the soluble guanylyl cyclase inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one. The two NONOates were approximately 15-fold more potent in SH-SY5Y than in NG108-15 cells, whereas the EC50 values of SIN-1 in SH-SY5Y and NG108-15 cells were in the same order. This led us to conclude that the mechanisms of NO and peroxynitrite did not converge. This was supported by our other findings. NONOates induced DNA fragmentation and an increase in cellular caspase-3 activity that preceded the gradual decline in cell viability. In contrast, SIN-1 induced a transient decline in ATP levels and a delayed loss of cell viability with no significant increase in caspase-3 activity or DNA laddering. Moreover, post-treatment with insulin inhibited caspase-3 activation and loss of cell viability in NONOate- but not in SIN-1-exposed cells. These findings suggest that NO is a potent toxin independent of peroxynitrite formation.
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PMID:Differential mechanisms of nitric oxide- and peroxynitrite-induced cell death. 1525 57

Here we present a basic concept and several examples of methods of analysis for chemicals that disrupt cellular signaling pathways, in view of risk assessment for potential endocrine disrupting chemicals (EDCs). The key cellular signaling pathways include 1) ER/coactivator interaction, 2) AR translocation into the nucleus, 3) ER/NO/sGC/cGMP, 4) ER/Akt, 5) ER/Src, 6)ER/Src/Grb2, and 7) ER/Ca2+/CaM/CaMK pathways. These were visualized in relevant live cells using newly developed fluorescent and bioluminescent probes. Changes in cellular signals were thereby observed in nongenomic pathways of steroid hormones upon treatment of the target cells with steroid hormones and related chemicals. This method of analysis appears to be a rational approach to high-throughput prescreening (HTPS) of biohazardous chemicals, EDCs, in particular. Also described was the screening of gene expression by serial analysis of gene expression and gene chips upon applying EDCs to breast cancer cells, mouse livers, and human neuroblastoma NB-1 cells.
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PMID:Methods of analysis for chemicals that disrupt cellular signaling pathways: risk assessment for potential endocrine disruptors. 1579 60

The effects of BAY 41-2272, a nitric oxide-independent activator of soluble guanylyl cyclase, on Ca2+ signalling and ion currents were investigated in pituitary GH3 cells. Intracellular Ca2+ concentrations ([Ca2+]i) in these cells were increased by BAY 41-2272. Removing extracellular Ca2+ abolished the BAY 41-2272-induced increase in [Ca2+]i. After [Ca2+]i was elevated by BAY 41-2272 (300 nmol/L), subsequent application of 1-benzyl-3-(5'-hydroxymethyl-2'-furyl) indazole (YC-1; 1 micromol/L) did not increase [Ca2+]i further. In whole-cell recordings, BAY 41-2272 reversibly stimulated Ca2+-activated K+ current (I(K(Ca))) with an EC50 of 225 +/- 8 nmol/L. At 3 micromol/L, BAY 41-2272 slightly and significantly decreased L-type Ca2+ current. In the cell-attached configuration, BAY 41-2272 (300 nmol/L) enhanced the activity of large-conductance Ca2+-activated K+ (BK(Ca)) channels. After BK(Ca) channel activity was stimulated by spermine NONOate (30 micromol/L) or YC-1 (10 micromol/L) in cell-attached patches, subsequent application of BAY 41-2272 (300 nmol/L) further increased the channel open probability. In the inside-out configuration, BAY 41-2272 applied to the intracellular surface of excised patches enhanced BK(Ca) channel activity. Unlike 1 micromol/L paxilline, 1H-[1,2,4]oxadiazolol-[4,3a] quinoxalin-1-one (ODQ; 10 micromol/L) or heme (10 micromol/L) had no effect on BAY 41-2272-stimulated channel activity. BAY 41-2272 caused no shift in the activation curve of BK(Ca) channels; however, it did increase the Ca2+ sensitivity of these channels. At 300 nmol/L, BAY 41-2272 reduced the firing rate of spontaneous action potentials stimulated by thyrotropin-releasing hormone (10 micromol/L). The BK(Ca) channel activity was also enhanced by 300 nmol/L BAY 41-2272 in neuroblastoma IMR-32 cells. Therefore, the BAY 41-2272-induced increase in [Ca2+]i is primarily explained by an increase in Ca2+ influx. The BAY 41-2272-mediated simulation of IK(Ca) may result from direct activation of BKCa channels and indirectly as a result of elevated [Ca2+]i.
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PMID:BAY 41-2272, a potent activator of soluble guanylyl cyclase, stimulates calcium elevation and calcium-activated potassium current in pituitary GH cells. 1644 74

Neurogranin (Ng), a calmodulin (CaM)-binding protein kinase C (PKC) substrate, regulates the availability of Ca(2+)/CaM complex and modulates the homeostasis of intracellular calcium in neurons. Previous work showed Ng oxidation by NO donor induces increase in [Ca(2+)](i). The current study demonstrated that the gene transcription of Ng could be up-regulated by various nitric oxide (NO) donors via a NO-soluble guanylyl cyclase (sGC)-mediated pathway. Furthermore, ectopic expression of neuronal nitric oxide synthase (nNOS) in human embryonic kidney 293 cells (HEK 293) exhibited a nNOS-concentration-dependent biphasic regulatory effect on Ng gene transcription. One of the NO donors, sodium nitroprusside (SNP), however, induced cell death of neuroblastoma Neuro-2a cells. The potency of SNP-induced cell death was shown to be higher in Neuro-2a cells expressing recombinant Ng, as compared with Neuro-2a control cells without Ng expression in cell viability and apoptosis assays. Single-cell fluorescence imaging and site-directed mutagenesis studies suggest that Ng promotes SNP-induced cell death through an amplification of calcium-mediated signaling, which requires the interaction between CaM and IQ motif of Ng. Increased neuronal susceptibility rendered by Ng in response to pathophysiological NO production is suggested to be involved in the selective vulnerability of neurons to oxidative insults in the CNS.
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PMID:Characterization of transcriptional regulation of neurogranin by nitric oxide and the role of neurogranin in SNP-induced cell death: implication of neurogranin in an increased neuronal susceptibility to oxidative stress. 1738 28

Adenosine triphosphate (ATP)-sensitive potassium (K(ATP)) channels couple cellular metabolic status to membrane electrical activity. In this study, we performed patch-clamp recordings to investigate how cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) regulates the function of K(ATP) channels, using both transfected human SH-SY5Y neuroblastoma cells and embryonic kidney (HEK) 293 cells. In intact SH-SY5Y cells, the single-channel currents of Kir6.2/sulfonylurea receptor (SUR) 1 channels, a neuronal-type K(ATP) isoform, were enhanced by zaprinast, a cGMP-specific phosphodiesterase inhibitor; this enhancement was abolished by inhibition of PKG, suggesting a stimulatory role of cGMP/PKG signaling in regulating the function of neuronal K(ATP) channels. Similar effects of cGMP accumulation were confirmed in intact HEK293 cells expressing Kir6.2/SUR1 channels. In contrast, direct application of purified PKG suppressed rather than activated Kir6.2/SUR1 channels in excised, inside-out patches, while tetrameric Kir6.2LRKR368/369/370/371AAAA channels expressed without the SUR subunit were not modulated by zaprinast or purified PKG. Lastly, reconstitution of the soluble guanylyl cyclase/cGMP/PKG signaling pathway by generation of nitric oxide led to Kir6.2/SUR1 channel activation in both cell types. Taken together, here, we report novel findings that PKG exerts dual functional regulation of neuronal K(ATP) channels in a SUR subunit-dependent manner, which may provide new means of therapeutic intervention for manipulating neuronal excitability and/or survival.
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PMID:Dual regulation of the ATP-sensitive potassium channel by activation of cGMP-dependent protein kinase. 1823 7

The effect of the potent soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) on neurite outgrowth and retraction was investigated in PC12 cells and SH-SY5Y human neuroblastoma cells. ODQ inhibited neurite outgrowth and triggered neurite retraction in the cells stimulated with nerve growth factor (NGF), staurosporine, or Y-27632. The nitric oxide (NO) scavenger 2-(4-carboxyphenyl)-4,4,5,5-tetramethyl-imidazoline-1-oxyl-3-oxide (PTIO) had little effect on neurite outgrowth induced by Y-27632 or staurosporine. In the presence of ODQ, treatment of the cells with the cell-permeable cGMP analogue 8-bromo-cGMP failed to retrigger Y-27632- and staurosporine-induced neurite outgrowth. Furthermore, the depletion of sGC by RNA interference failed to prevent Y-27632- and staurosporine-induced neurite outgrowth. These results indicate that the NO/sGC/cGMP signaling cascade is not critically involved in ODQ-induced neurite remodeling. The MEK inhibitor PD98059 did not inhibit neurite outgrowth, and Y-27632 and staurosporine did not induce ERK phosphorylation, suggesting that the inhibitory effect of ODQ on neurite outgrowth is independent of the ERK signaling pathway. In contrast, pretreatment with dithionite or a hemin-glutathione mixture reversed the inhibitory effect of ODQ on Y-27632- and staurosporine-induced neurite outgrowth, indicating that ODQ might act on an intracellular redox-sensitive molecule. We conclude that ODQ inhibits Y-27632- and staurosporine-induced neurite outgrowth and triggers neurite retraction in an sGC-independent manner in neuronal cells and suggest that oxidation of unidentified redox-sensitive protein could be responsible for these effects.
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PMID:1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one inhibits neurite outgrowth and causes neurite retraction in PC12 cells independently of soluble guanylyl cyclase. 1871 50

In this study the mechanism by which S-nitrosocysteine (CysNO) activates soluble guanylyl cyclase (sGC) has been investigated. CysNO is the S-nitrosated derivative of the amino acid cysteine and has previously been shown to be transported into various cell types by amino acid transport system L. Here we show, using both neuroblastoma and pulmonary artery smooth muscle cells, that CysNO stimulates cGMP formation at low concentrations, but this effect is lost at higher concentrations. Stimulation of cGMP accumulation occurs only after its transport into the cell and subsequent flavoprotein reductase-mediated metabolism to form nitric oxide (NO). Consequently, CysNO can be regarded as a cell-targeted NO-releasing agent. However, CysNO also functions as an NO-independent thiol-modifying agent and can compromise cellular antioxidant defenses in a concentration-dependent manner. The observed biphasic nature of CysNO-dependent cGMP accumulation seems to be due to these two competing mechanisms. At higher concentrations, CysNO probably inactivates guanylyl cyclase through modification of an essential thiol group on the enzyme, either directly or as a result of a more generalized oxidative stress. We show here that higher concentrations of CysNO can increase cellular S-nitrosothiol content to nonphysiological levels, deplete cellular glutathione, and inhibit cGMP formation in parallel. Although the inhibition of sGC by S-nitrosation has been suggested as a mechanism of nitrovasodilator tolerance, in the case of CysNO, it seems to be more a reflection of a generalized oxidative stress placed upon the cell by the nonphysiological levels of intracellular S-nitrosothiol generated upon CysNO exposure.
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PMID:Activation and inhibition of soluble guanylyl cyclase by S-nitrosocysteine: involvement of amino acid transport system L. 1940 84


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