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)

Major depression is frequently associated with hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. Clinically effective therapy with antidepressant drugs normalizes the disturbed activity of HPA axis, in part, by decreasing corticotropin-releasing hormone (CRH) synthesis, but the mechanism of this action is poorly recognized. In order to find out whether antidepressants directly affect CRH gene promoter activity, we studied their effect on undifferentiated and differentiated Neuro-2A cells, and for comparison the effect of the selected antidepressants on AtT-20 cells was also determined. The cells were stably transfected with a human CRH promoter fragment (-663 to +124 bp) linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The regulation of CRH gene promoter activity is similar in Neuro-2A cells, both intact and differentiated, and in AtT-20 cell line, and cAMP/PKA-dependent pathway plays an important role in the stimulation of CRH gene. It was found that imipramine, amitryptyline, desipramine, fluoxetine, and mianserin, present in the culture medium for 5 days, in a concentration-dependent manner inhibited basal hCRH gene promoter activity in undifferentiated Neuro-2A cells, while other drugs under study (citalopram, tianeptine, moclobemide, venlafaxine, reboxetine, mirtazapine, and milnacipram) were inactive. In the differentiated cells, all examined antidepressants, except moclobemide (no effect) and tianeptine (increase), inhibited hCRH gene transcription. Moreover, in differentiated cells, the drugs acted stronger and were effective at lower concentrations. Forskolin-induced CAT activity was attenuated by imipramine and fluoxetine and to a lesser degree by amitriptyline and desipramine in differentiated cells, whereas other drugs were inactive. Moreover, imipramine and fluoxetine, but not tianeptine, showed moderate inhibitory effect on CRH gene promoter activity also in AtT-20 cell line, commonly used in CRH gene regulation studies. These results indicate that neuron-like differentiated Neuro-2A cells are a better model than pituitary and intact neuroblastoma to investigate the mechanism of psychotropic drug action. Inhibition of CRH gene promoter activity by antidepressant drugs may be a molecular mechanism by which these drugs inhibit the activity of HPA axis.
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PMID:Regulation of the human corticotropin-releasing-hormone gene promoter activity by antidepressant drugs in Neuro-2A and AtT-20 cells. 1473 30

In addition to their inhibitory effects, cannabinoids also exert stimulatory activity which can be detected at the cellular level. In a previous study, we demonstrated a stimulatory effect of the synthetic cannabinoid receptor agonist desacetyllevonantradol (DALN) on Ca(2+) flux into N18TG2 neuroblastoma cells, and suggested a dual mechanism: one pathway mediated by PKA and the other one by protein kinase C (PKC). Here we studied the PKC-mediated effect of DALN on Ca(2+) influx. The stimulatory effect of DALN on Ca(2+) influx was partially blocked by the PKC inhibitor chelerythrine, by the metalloprotease inhibitor o-phenanthroline and by the MEK (mitogen-activated protein-kinase kinase, MAPK kinase) inhibitor PD98059. Immunobloting of ERK1/2 MAPK demonstrated phosphorylation by DALN, and indicated the involvement of vascular endothelial growth factor (VEGF) receptor tyrosin kinases (RTKs) in MAPK activation as it was blocked by oxindole-1. Transactivation of the VEGFR-MAPK cascade by DALN involved CB1 cannabinoid receptors coupled to Gi/Go GTP-binding proteins as it was blocked by SR141716A and by pertussis toxin (PTX). The pharmacological implications of this novel mechanism of cannabinoid activity are discussed.
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PMID:The involvement of VEGF receptors and MAPK in the cannabinoid potentiation of Ca2+ flux into N18TG2 neuroblastoma cells. 1474 3

We investigated the signal pathway related to induction of Nurr1, transcription factor, by cAMP in neuroblastoma N2A and C6 glioma cell lines. Nurr1 expression was induced by forskolin, an adenylate cyclase activator, via activation of CREB in both N2A and C6 cells. The effect of forskolin on ERK, however, was cell specific. ERK phosphorylation was stimulated by forskolin in N2A cells whereas it was inhibited in C6 cells. Pretreatment with H89, a PKA inhibitor, blocked the forskolin-induced Nurr1 expression in both N2A and C6 cells. Interestingly, pretreatment with PD98059, an MEK inhibitor, showed differential effects. Pretreatment with PD98059 inhibited the forskolin-induced Nurr1 expression in N2A cells, however, in C6 cells, Nurr1 expression was further increased. Our results suggest that ERK pathway plays a differential role in cAMP-induced Nurr1 expression in N2A and C6 cells.
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PMID:Differential role of ERK in cAMP-induced Nurr1 expression in N2A and C6 cells. 1510 39

We report the full genomic organization of the human gene for the corticotropin-releasing factor (CRF) receptor type 1 (CRFR1), with complete mapping of exons 1-14. The 5' flanking region (2.4 kb) of the gene encoding for human CRFR1 was isolated, sequenced, and characterized. Two major transcriptional start sites were determined at -265 and -238, relative to the ATG start site (+1). Transient expression of constructs containing sequentially deleted 5'-flanking sequences of CRFR1 fused to luciferase, revealed the minimal promoter sequence 370 bp in size, as shown by assays in neuroblastoma (SH-5YSY), teratocarcinoma (NT2), and adenocarcinoma (MCF 7) cell lines. CRF and UCN markedly increased promoter activity during transient CRFR1 expression studies. Similarly, CRF and UCN up-regulate the endogenous CRFR1 at the mRNA level in NT2 and MCF 7 cells. To dissect further the mechanisms involved, we have used primary myometrial cells transfected with the CRFR1 promoter. CRF and UCN increased the promoter activity, an effect blocked by protein kinase (PK)A and PKC inhibitors. Both CRF and UCN cause a positive feedback effect in primary cultures of human pregnant myometrial cells, by increasing mRNA expression of CRFR1. This effect appears to be dependent on activation of both PKA and PKC by CRF, whereas UCN's effect was mediated solely via PKC activation. Collectively, our data suggest that the CRFR1 gene is under the influence of both CRF and UCN, acting via distinct signaling pathways to create a positive feedback loop and regulate further the transcription of the receptor.
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PMID:Promoter analysis of human corticotropin-releasing factor (CRF) type 1 receptor and regulation by CRF and urocortin. 1514 84

We had reported that activation of presynaptic histamine H(3)-receptors inhibits norepinephrine exocytosis from depolarized cardiac sympathetic nerve endings, an action associated with a marked decrease in intraneuronal Ca(2+) that we ascribed to a decreased Ca(2+) influx. An H(3)-receptor-mediated inhibition of cAMP-dependent phosphorylation of Ca(2+) channels could cause a sequential attenuation of Ca(2+) influx, intraneuronal Ca(2+) and norepinephrine exocytosis. We tested this hypothesis in sympathetic nerve endings (cardiac synaptosomes) expressing native H(3)-receptors and in human neuroblastoma SH-SY5Y cells transfected with H(3)-receptors. Norepinephrine exocytosis was elicited by K(+) or by stimulation of adenylyl cyclase with forskolin. H(3)-receptor activation markedly attenuated the K(+)- and forskolin-induced norepinephrine exocytosis; pretreatment with pertussis toxin prevented this effect. Similar to forskolin, 8-bromo-cAMP elicited norepinephrine exocytosis but, unlike forskolin, it was unaffected by H(3)-receptor activation, demonstrating that inhibition of adenylyl cyclase is a pivotal step in the H(3)-receptor transductional cascade. Indeed, we found that H(3)-receptor activation attenuated norepinephrine exocytosis concomitantly with a decrease in intracellular cAMP and PKA activity in SH-SY5Y-H(3) cells. Moreover, pharmacological PKA inhibition acted synergistically with H(3)-receptor activation to reduce K(+)-induced peak intracellular Ca(2+) in SH-SY5Y-H(3) cells and norepinephrine exocytosis in cardiac synaptosomes. Furthermore, H(3)-receptor activation synergized with N- and L-type Ca(2+) channel blockers to reduce norepinephrine exocytosis in cardiac synaptosomes. Our findings suggest that the H(3)-receptor-mediated inhibition of norepinephrine exocytosis from cardiac sympathetic nerves results sequentially from H(3)-receptor-G(i)/G(o) coupling, inhibition of adenylyl cyclase activity, and decreased cAMP formation, leading to diminished PKA activity, and thus, decreased Ca(2+) influx through voltage-operated Ca(2+) channels.
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PMID:Histamine H3-receptor-induced attenuation of norepinephrine exocytosis: a decreased protein kinase a activity mediates a reduction in intracellular calcium. 1530 34

Although corticotropin-releasing hormone (CRH) plays a pivotal role in the regulation of the hypothalamo-pituitary-adrenal axis, the mechanism of CRH gene expression in the neuronal cell is not completely understood. In this study, we examined the transcriptional regulation of human CRH gene 5'-promoter, using a human BE(2)C neuroblastoma cell line expressing intrinsic CRH. In particular, we focused on the involvement of calmodulin kinases (CaMKs), which are known to play an important role in excitation-induced gene expression through the rise in intracellular calcium in the central nervous system. RT-PCR analysis confirmed the expression of CaMK as well as CRH mRNA in BE(2)C cells. When we introduced approximately 1.1 kb of the 5'-promoter region of the human CRH fused with luciferase reporter gene into the cells, a substantial transcriptional activity was observed, and this was further increased by the activation of the cAMP/PKA pathway. We then examined the effect of activation of CaMKs by introducing the expression vectors of each kinase, revealing a potent stimulatory effect of CaMKIV, but no effect of CaMKII. Depolarization of the cells caused an increase in CRH promoter activity, which was completely abolished by the treatment with the CaMK antagonist K252a. Interestingly, KCREB, a dominant negative form of CREB, antagonized the effect of the CaMKIV-mediated effect. Altogether, we conclude that not only the cAMP/PKA but also the calcium/CaMKIV signaling pathway is involved in the regulation of CRH gene expression. Furthermore, CREB is thought to be involved in CaMK- as well as cAMP/PKA-mediated CRH gene expression. Since the CRH gene is expressed in the neuronal cells of the hypothalamus, the calcium/CaMKIV signaling pathway may play an important role in the excitation-mediated regulation of CRH synthesis.
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PMID:Calcium/calmodulin kinase IV pathway is involved in the transcriptional regulation of the corticotropin-releasing hormone gene promoter in neuronal cells. 1559 Oct 24

Hypothalamic proTRH mRNA levels are rapidly increased (at 1 h) in vivo by cold exposure or suckling, and in vitro by 8Br-cAMP or glucocorticoids. The aim of this work was to study whether these effects occurred at the transcriptional level. Hypothalamic cells transfected with rat TRH promoter (-776/+85) linked to the luciferase reporter showed increased transcription by protein kinase (PK) A and PKC activators, or by dexamethasone (dex), but co-incubation with dex and 8Br-cAMP decreased their stimulatory effect (as observed for proTRH mRNA levels). These effects were also observed in NIH-3T3-transfected cells supporting a characteristic of TRH promoter and not of hypothalamic cells. Transcriptional regulation by 8Br-cAMP was mimicked by noradrenaline which increased proTRH mRNA levels, but not in the presence of dex. PKA inhibition by H89 avoided 8Br-cAMP or noradrenaline stimulation. TRH promoter sequences, cAMP response element (CRE)-like (-101/-94 and -59/-52) and glucocorticoid response element (GRE) half-site (-210/-205), were analyzed by electrophoretic mobility shift assays with nuclear extracts from hypothalamic or neuroblastoma cultures. PKA stimulation increased binding to CRE (-101/-94) but not to CRE (-59/-52); dex or 12-O-tetradecanoylphorbol-13-acetate (TPA) increased binding to GRE, a composite site flanked by a perfect and an imperfect activator protein (AP-1) site in the complementary strand. Interference was observed in the binding of CRE or GRE with nuclear extracts from cells co-incubated for 3 h with 8Br-cAMP and dex; from cells incubated for 1 h, only the binding to GRE showed interference. Rapid cross-talk of glucocorticoids with PKA signaling pathways regulating TRH transcription constitutes another example of neuroendocrine integration.
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PMID:Dexamethasone represses cAMP rapid upregulation of TRH gene transcription: identification of a composite glucocorticoid response element and a cAMP response element in TRH promoter. 1569 87

Disturbances in Galpha(s-L) levels and function have been implicated in the pathophysiology of bipolar disorder, but the role of these changes in the development of the illness is not clear. In view of the critical role of Galpha(s)-mediated cAMP signaling in regulating cell survival, we investigated the potential role of Galpha(s-L) in modulating susceptibility to cellular stressors in human SH-SY5Y neuroblastoma cells. Overexpression of Galpha(s-L) to a level twice that of the vector-transfected cells did not directly affect cell viability but significantly increased the sensitivity to induction of cell death by serum deprivation and other apoptotic stimuli, including staurosporine, H(2)O(2), and tunicamycin. This enhanced sensitivity was associated with increased caspase-3 activation and appearance of fragmented nuclei (Hoechst 33342 staining). The broad-spectrum caspase inhibitor z-VAD-fmk completely suppressed cell death evoked by these apoptotic insults in both vector-transfected and Galpha(s-L)-overexpressing cells. The increased vulnerability conferred by increased Galpha(s-L) expression was neither mimicked by cAMP analogs 8-Br-cAMP, 8-CPT-cAMP, and 8-CPT-2Me-cAMP nor attenuated by PKA inhibitors Rp-cAMPS and KT5720. These data indicate that Galpha(s-L) may modulate apoptotic processes in a caspase-dependent manner through a signaling cascade that is independent of the cAMP/PKA or cAMP/Epac pathway. These results suggest that enhanced Galpha(s-L) expression, as was observed in post-mortem brain of bipolar patients, may impair cellular resilience in response to intracellular stress signals resulting from mitochondrial and/or endoplasmic reticulum dysfunction implicated in this disorder.
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PMID:Galpha(s) sensitizes human SH-SY5Y cells to apoptosis independently of the protein kinase A pathway. 1667 98

Dopamine and norepinephrine are neurotransmitters which participate in various regulatory functions of the human brain. These functions are lost in neurodegenerative diseases including Parkinson's disease and Alzheimer's disease. In this study, we used SK-N-MC neuroblastoma cells to investigate the cytotoxicities of high concentrations of dopamine and norepinephrine on neuronal cells. Dopamine, norepinephrine, as well as their corresponding synthetic agonists (SKF38393 and isoproterenol, respectively) triggered SK-N-MC cell death when applied at 50-100 muM persistently for 2 days. This catecholamine-induced cell death appears to be neuronal specific, as demonstrated by their inabilities of triggering apoptosis of A549 lung carcinoma cells and Cos-7 kidney fibroblasts. By pretreating SK-N-MC cells with target-specific inhibitors before administration of catecholamine, components of G protein signaling (i.e. G( s )/cAMP/PKA), monoamine oxidases, nitric oxide synthase, c-Jun N-terminal kinase and oxidative stress were found to be involved in this dopamine/norepinephrine-induced cytotoxicity, which subsequently led to caspase-dependent and -independent apoptotic responses as well as DNA degradation. In contrast, agonists of G( i )-coupled dopamine receptors and adrenergic receptors (quinpirole and UK14,304, respectively) were incapable of triggering apoptosis of SK-N-MC cells. Our results suggest that both G protein (G( s ))-mediated signaling cascade and oxidative stress participate in the dopamine/norepinephrine-induced neuronal apoptosis.
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PMID:Dopaminergic and adrenergic toxicities on SK-N-MC human neuroblastoma cells are mediated through G protein signaling and oxidative stress. 1713 23

We hypothesized that the histamine H(3)-receptor (H(3)R)-mediated attenuation of norepinephrine (NE) exocytosis from cardiac sympathetic nerves results not only from a Galpha(i)-mediated inhibition of the adenylyl cyclase-cAMP-PKA pathway, but also from a Gbetagamma(i)-mediated activation of the MAPK-PLA(2) cascade, culminating in the formation of an arachidonate metabolite with anti-exocytotic characteristics (e.g., PGE(2)). We report that in Langendorff-perfused guinea-pig hearts and isolated sympathetic nerve endings (cardiac synaptosomes), H(3)R-mediated attenuation of K(+)-induced NE exocytosis was prevented by MAPK and PLA(2) inhibitors, and by cyclooxygenase and EP(3)-receptor (EP(3)R) antagonists. Moreover, H(3)R activation resulted in MAPK phosphorylation in H(3)R-transfected SH-SY5Y neuroblastoma cells, and in PLA(2) activation and PGE(2) production in cardiac synaptosomes; H(3)R-induced MAPK phosphorylation was prevented by an anti-betagamma peptide. Synergism between H(3)R and EP(3)R agonists (i.e., imetit and sulprostone, respectively) suggested that PGE(2) may be a downstream effector of the anti-exocytotic effect of H(3)R activation. Furthermore, the anti-exocytotic effect of imetit and sulprostone was potentiated by the N-type Ca(2+)-channel antagonist omega-conotoxin GVIA, and prevented by an anti-Gbetagamma peptide. Our findings imply that an EP(3)R Gbetagamma(i)-induced decrease in Ca(2+) influx through N-type Ca(2+)-channels is involved in the PGE(2)/EP(3)R-mediated attenuation of NE exocytosis elicited by H(3)R activation. Conceivably, activation of the Gbetagamma(i) subunit of H(3)R and EP(3)R may also inhibit Ca(2+) entry directly, independent of MAPK intervention. As heart failure, myocardial ischemia and arrhythmic dysfunction are associated with excessive local NE release, attenuation of NE release by H(3)R activation is cardioprotective. Accordingly, this novel H(3)R signaling pathway may ultimately bear therapeutic significance in hyper-adrenergic states.
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PMID:Histamine H3-receptor signaling in cardiac sympathetic nerves: Identification of a novel MAPK-PLA2-COX-PGE2-EP3R pathway. 1726 40


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