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)

Transcriptional regulation of the rat tyrosine hydroxylase (TH) gene by prostaglandin E2 (PGE2) was investigated in human neuroblastoma SK-N-BE(2)C cells. Prostaglandins increased intracellular cAMP in the presence of 3-isobutyl-1-methylxanthine (IBMX), a cAMP phosphodiesterase inhibitor. Among the prostaglandins tested for their cAMP raising property PGE2 was the most effective. The results suggest that the cells express adenylyl cyclase-linked prostanoid receptors that have a higher affinity for PGE2 than for any other naturally occurring prostaglandin. The treatment of cells with PGE2 increased the TH gene expression approximately 2-fold, even though the cAMP accumulation induced by PGE2 alone was almost negligible. Simultaneous treatment with PGE2 and IBMX enhanced the gene expression concomitantly with a marked accumulation of cAMP. Transient transfection assays with 5' upstream serially deleted constructs of the rat TH gene promoter region fused to the chloramphenicol acetyltransferase (CAT) gene revealed that a cAMP response element (CRE) located at -45 to -38 from the start of the TH gene was essential for the enhancement of TH gene expression by PGE2. Site-directed mutagenesis and specific deletion within the sequence of the CRE motif abolished the transcriptional enhancement by PGE2. In addition, a protein kinase A (PKA) inhibitor, H89, specifically blocked the PGE2 effect on TH gene expression. Northern blot analysis revealed that the increase in TH gene transcription with PGE2 is associated with an elevated TH mRNA level. Gel retardation and competition assays confirmed that the binding of nuclear factors to the CRE site was sequence specific and was augmented by PGE2. Our data indicate that PGE2 enhances transcription of the TH gene mediated by the CRE motif through the activation of PKA. They also suggest that the signal flow from the adenylyl cyclase-linked prostanoid receptor to the nucleus is efficient although cAMP accumulation is not prominent.
 ...
PMID:Transcriptional enhancement of tyrosine hydroxylase by prostaglandin E2 in SK-N-BE(2) C cells. 880 26

Using purified microglial cultures obtained from the neonatal rat brain we found that media containing fetal calf serum (as well as human, horse and goat sera) enhanced by about 3-fold the accumulation of cyclic AMP induced by the beta-adrenergic agonist isoproterenol and did not affect in a significant way that induced by the direct adenylyl cyclase stimulator forskolin. The effect of fetal calf serum was (i) dose dependent, and statistically significant also at serum concentrations below 1%; (ii) rapidly lost (half life of about 15 min) when the serum-containing medium was exposed to microglia, astrocytes or neuroblastoma cells; (iii) present also when cyclic AMP accumulation was enhanced by prostaglandin E2 or by cholera toxin; (iv) absent on basal cyclic AMP levels. When media containing fetal calf serum or the other mammalian sera mentioned above were tested on astrocyte cultures, an inhibitory, rather than enhancing activity on cyclic AMP levels was observed, indicating that the facilitatory factor(s) present in serum acts specifically on microglial cells. Moreover, in astrocytes the effect of serum was identical when tested on basal and on isoproterenol or forskolin-stimulated cyclic AMP levels. Thus, the mechanism of cyclic AMP inhibition in astrocytes is unrelated to the mechanism of activation in microglia. Our observations suggest that serum contains factor(s), promptly cleared by different cell types. Such factors may interact with so far unidentified microglial receptors responsible for a facilitation of G protein-mediated activation of adenylyl cyclase. Regulation of the cyclic AMP cascade at this step has not been described previously, and may be important for the modulation of microglial functions controlled by the cyclic nucleotide.
 ...
PMID:Selective enhancement by serum factors of cyclic AMP accumulation in rat microglial cultures. 880 93

The cannabinoid receptors expressed in the mouse neuroblastoma X rat glioma NG108-15 cell and the rat pituitary tumor GH4C1 cell were determined by polymerase chain reaction, dideoxysequencing and pharmacologically. The CB1 but not the CB2 or CB1A cannabinoid receptor was found in both cell lines. The cDNA identified in GH4C1 cells corresponds to the rat CB1 receptor. Interestingly, NG108-15 cells express two distinct cDNAs, one corresponds to the rat and the other to the mouse CB1 receptor. The newly developed CB1 receptor selective antagonist SR141716A was found to reverse cannabinoid agonist (WIN55212-2 or CP55940)-induced adenylyl cyclase inhibition. These results provide more direct evidence that the CB1 receptor is mediating the pharmacological actions of cannabinoids in NG108-15 and GH4C1 cells.
 ...
PMID:Determination of the cannabinoid receptors in mouse x rat hybridoma NG108-15 cells and rat GH4C1 cells. 883 54

Recent studies have demonstrated that opioid agonists affect the cytosolic Ca2+ concentration ([Ca2+]i) either by regulating plasma membrane Ca(2+)-channel activity or by mobilizing intracellular Ca2+ stores. The present report documents the [Ca2+]i increase induced by opioid agonists in a human neuroblastoma cell line, SK-N-BE, expressing delta-opioid receptors. In the presence, as well as in the absence, of extracellular Ca2+, opioid agonists enhanced significantly [Ca2+]i, whereas carbachol, known to mobilize specifically inositol 1,4,5-trisphosphate-sensitive intracellular Ca2+ stores, acted only in the presence of extracellular Ca2+. The opioid-induced increase in [Ca2+]i was not affected by treatments modifying the trimeric Gl, Go, and Gs protein transduction mechanisms or the activity of adenylyl cyclase. The Ca(2+)-ATPase pump-inhibiting sesquiterpene lactone, thapsigargin, did not modify the opioid-induced [Ca2+]i response, whereas it abolished the effects of carbachol. The Ryana speciosa alkaloid, ryanodine, at concentrations known to block endoplasmic reticulum ryanodine receptors, decreased significantly the response to opioids without affecting the effects of carbachol. Thus, our results suggest that, in SK-N-BE cells, delta-opioid receptors mobilize Ca2+ from intracellular ryanodine-sensitive stores and the mechanism involved is independent of Gl/Go Gs proteins and protein kinase A activation.
 ...
PMID:The delta-opioid receptor regulates activity of ryanodine receptors in the human neuroblastoma cell line SK-N-BE. 893 79

1-[6-[17 beta-3-Methoxyestra-1,3.5(10)-trien-17-yl]amino]hexyl]-1 H-pyrrole-2,5-dione (U-73122), an inhibitor of processes involved in the activation of phospholipase C, was used to assess the role of phospholipase C activation in the synergistic elevation of cAMP induced by carbachol and prostaglandin E2 in human neuroblastoma (SK-N-BE(2)C cells. Pre-treatment of the cells with U-73122 resulted in inhibition of carbachol-induced intracellular Ca2+ ([Ca2+]i) rise and inositol 1,4,5-trisphosphate (InsP3) generation, with maximal and half maximal inhibition (IC50) occurring at approximately 15 microM and 3.2 microM, respectively. U-731222 also inhibited the synergistic enhancement of cAMP accumulation induced by carbachol and prostaglandin E2 in a concentration-dependent manner with maximum and IC50 at 12 +/- 4 microM and 3.4 +/- 0.3 microM, respectively. However, U-73122 did significantly inhibit prostaglandin E2-induced production. While 1,2-bis(o-aminophenoxy)ethane-N,N,N,'N'-tetraacetic acid (BAPTA/AM) treatment decreased the synergistic cAMP accumulation by 28%m addition U-73122 further decreased it down to complete inhibition. Furthermore, GTP gamma S- and A1F4(-)-induced InsP3 generation in digitonin-mediated permeabilized cells was also inhibited by U-73122 treatment. Pre-treatment of the cells with neomycin, another blocker of the phospholipase C pathway, also resulted in inhibition of the carbachol-induced [Ca2+]i rise, InsP3 generation, and the enhancing effect on cAMP accumulation, to a comparable extent. But, Ca2+ chelation by BAPTA/AM in addition to neomycin treatment further decreased the cAMP accumulation. These results suggest that the increase in cytosolic Ca2+ and the coupling process between muscarinic receptor-like G-protein and phospholipase C are important for the synergistic activation of adenylyl cyclase in SK-N-BE(2)C cells.
 ...
PMID:Synergistic activation of adenylyl cyclase is dependent upon phospholipase C-mediated processes in human neuroblastoma SK-N-BE(2)C cells. 895 41

Neuroblastoma X glioma hybrid NG108-15 cells were transfected to express stably either the wild-type human beta2-adrenoceptor or a constitutively active mutant (CAM) version of this receptor. Basal adenylyl cyclase activity in cells expressing the CAM beta2-adrenoceptor correlated well with the level of expression of the receptor and was substantially greater than that in cells expressing the wild-type beta2-adrenoceptor. The CAM beta2-adrenoceptor displayed higher affinity for the agonist isoprenaline than the wild-type receptor but not for the antagonist alprenolol or the inverse agonist betaxolol. Pretreatment of cells harboring the CAM beta2-adrenoceptor with betaxolol resulted in a large (4-7-fold within 24 hr) up-regulation in levels of this receptor. This was not observed after exposure of the CAM beta2-adrenoceptor-expressing cells to alprenolol, and a much smaller effect of betaxolol was produced in cells expressing the wild-type receptor. Betaxolol-mediated up-regulation of the CAM beta2-adrenoceptor was both time and concentration dependent. However, this up-regulation did not result in a substantial alteration in the cellular distribution profile of the receptor. Half-maximal up-regulation of the CAM beta2-adrenoceptor required concentrations of betaxolol similar to those needed to cause half-maximal inhibition of basal adenylyl cyclase activity, indicating the receptor up-regulation is associated with the inverse agonist properties of this compound. Despite the large up-regulation of CAM beta2-adrenoceptor levels, treatment with betaxolol did not significantly alter levels of the G protein that couples to this receptor (G(Salpha)). After sustained treatment with betaxolol, Northern analyses did not demonstrate up-regulation of either CAM beta2-adrenoceptor or G(Salpha) mRNA, and up-regulation of the receptor was prevented by cotreatment of the cells with cycloheximide. These data indicate that the up-regulation of the receptor by betaxolol is likely to reflect an increase in translational efficiency of existing mRNA and/or stabilization of the receptor polypeptide from proteolytic degradation and indicate that such effects can be produced by inverse agonists but not by neutral antagonists.
 ...
PMID:Inverse agonist-induced up-regulation of the human beta2-adrenoceptor in transfected neuroblastoma X glioma hybrid cells. 896 68

In the human neuroblastoma cell line Lan-1, the mRNA encoding the Ca2+/calmodulin (CaM) sensitive adenylyl cyclase type-1 (AC-1) was detected by reverse transcription-polymerase chain reaction (RT-PCR) as well as by Northern blotting. However, neither Ca2+/CaM stimulated AC activity was found nor could AC-1 type protein be detected by a specific antibody (anti-1Cl). In contrast, when cells were grown to high cell density, Ca2+/CaM stimulated AC-activity could be indeed found in membranes. The large increase in activity was paralleled by the appearance of a 110 kDa protein detected by the monoclonal AC antibody BBC-2. At the same time a 150 kDa adenylyl cyclase species present in growing cells was absent. The 110 kDa protein co-migrated with bovine AC-1 and was slightly larger than the human AC-1. Unexpectedly, however, the antibody anti-1CI was not able to precipitate the newly induced Lan-1 AC. In addition, no increase in type-1 AC mRNA could be detected either by PCR or by Northern blotting. Treatment of Lan-1 cells with 10 microM retinoic acid for 7 days caused growth arrest and morphological differentiation of the cells, yet the induction of the Ca2+/CaM-stimulated AC activity was much lower than in the dense grown control cultures. It is concluded that the Ca2+/CaM-activated AC of M(r) 110 kDa in Lan-1 cells is not related to the previously known Ca2+/CaM stimulated AC isoforms, and might thus represent a novel AC.
 ...
PMID:The expression of a novel Ca2+/CaM stimulated adenylyl cyclase activity in the neuroblastoma cell line Lan-1 is regulated by cell density. 897 11

Exposure of human neuroblastoma SK-N-MC cells to 100 microM dopamine (DA) for 72 h caused 70% loss of immunodetectable membrane-bound levels of the alpha-subunit of Ga. The loss in Gs alpha was accompanied by reduced (64.3 +/- 0.35% of control values) NaF-mediated stimulation of adenylyl cyclase and was independent of accumulated cyclic AMP (cAMP) levels, because neither forskolin nor dibutyryl cAMP treatment of cells mimicked the DA-induced effects. The reduction in Gs alpha content was manifest at the transcriptional level; Gs alpha mRNA levels were attenuated to 56.5 +/- 10% of control values after a 24-h treatment of cells with 100 microM DA. The concentration of DA required to produce the half-maximal decrease of Gs alpha mRNA content was 20 nM, similar to the high-affinity binding value (8.5 nM) of DA to D1 sites. Gs alpha mRNA levels were also attenuated (52 +/- 3.5% of control values) by the D1-selective agonist SKF R-38393 but not by forskolin or dibutyryl cAMP. Attenuation of Gs alpha mRNA levels by agonists was blocked by the D1-selective antagonist SCH 23390. Stimulation of adenylyl cyclase-inhibitory DA receptors, which are coexpressed in these cells, failed to down-regulate Gs alpha mRNA, indicating that regulation of Gs alpha mRNA expression occurs specifically through chronic stimulation of D1 DA receptors.
 ...
PMID:A novel regulation of expression of the alpha-subunit of the G stimulatory protein by dopamine via D1 dopamine receptors. 897 25

In neuroblastoma X glioma hybrid, NG1O8-15, cells transfected to stably express a constitutively active mutant (CAM) form of the human beta2-adrenoceptor, the beta-adrenoceptor ligands sotalol and betaxolol functioned as inverse agonists as they reduced basal adenylyl cyclase activity whereas the antagonists dihydroalprenolol and propranolol did not. Maintained presence of the CAMbeta2-adrenoceptor inverse agonists but not the antagonists in the culture medium of the cells resulted in a substantial, concentration-dependent, up-regulation of the CAMbeta2-adrenoceptor. Up-regulation of the CAMbeta2-adrenoceptor by the inverse agonists was prevented by co-incubation of the cells with either propranolol or dihydroalprenolol. Neither maintained elevation of cAMP levels nor the inhibition of adenylyl cyclase activity altered the ability of the inverse agonist ligands to cause receptor up-regulation.
 ...
PMID:Up-regulation of a constitutively active form of the beta2-adrenoceptor by sustained treatment with inverse agonists but not antagonists. 898 Jan 31

Thrombin receptor-G protein coupling was investigated in the human epithelial neuroblastoma cell line, SH-EP. In these cells, both alpha-thrombin and thrombin receptor peptides, SFLLRNP (one-letter amino-acid code), which are newly exposed following cleavage by alpha-thrombin, stimulated GTPase activity about 2-fold over basal activity. Pertussis toxin treatment only partially attenuated alpha-thrombin- and SFLLRNP-stimulated GTPase activity by 50%, whereas antibody raised against synthetic heptapeptide SFLLRNP blocked alpha-thrombin-stimulated phosphoinositide hydrolysis more than 80%. Immunoprecipitation studies using this antibody showed that both Gi2, a subtype of guanine nucleotide-binding regulatory proteins (G proteins) mediating inhibition of adenylyl cyclase, and Gq/G11, a G protein mediating stimulation of phospholipase C, were activated by alpha-thrombin. These data suggest that in these cells the thrombin receptor activates pertussis toxin-sensitive and pertussis toxin-insensitive G proteins simultaneously and directly couples to Gi2 and Gq/G11, which mediate different signaling pathways.
 ...
PMID:Direct evidence for two distinct G proteins coupling with thrombin receptors in human neuroblastoma SH-EP cells. 898 57


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