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)

In this work, we have studied the activity of a tetracycline modulatable trans-activator (tTA) generated by fusing the DNA binding domain of the tetracycline repressor to the trans-activation domain of the Herpes simplex virus protein 16 (HSV VP16) (plasmid pUHD15-1Neo). In the three different cell lines studied (HTC, rat hepatoma; T47D, human breast cancer; SK-N-BE, human neuroblastoma), the expression of the luciferase gene under the control of a tetracycline operator sequence (plasmid pUHC13-3) was used as a control of the incorporation and the functionality of the trans-activator. Clones selected from these cells responded in a time and dose-dependent manner to the withdrawal of tetracycline. In all these clones, the tTA trans-activator not only modulates the activity of the luciferase gene, but also modulates the activity of a number of endogenous proteins, including C/EBP beta, the glucocorticoid receptor (GR), and SP1. In the transfected cells, the level of these transcription factors was strongly inhibited in the presence of tetracycline and was highly increased after tetracycline removal. Electrophoresis mobility shift assay (EMSA) and footprint experiments proved that the induced proteins are perfectly efficient in binding the DNA. Their transcriptional activity was also determined. In HTC/A9 cells, the level of the chloramphenicol acetyltransferase (CAT) expression driven by the promoter of the alpha 1-glycoprotein (AGP) gene was strongly enhanced at 72-84 hr following removal of tetracycline from the growth media. The accumulation of the endogenous AGP mRNA also increased at 84 hr. In the T47D/TA11 and SK-N-BE/C2.6 cells, a general activation of protein synthesis was also evidenced.
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PMID:Specificity of action of a herpes virus VP16/tetracycline-dependent trans-activator in mammalian cell cultures. 764 13

Neuron-specific enolase (NSE) occurs in mature neurons and paraneurons. We have isolated the genomic clone coding for rat NSE and clarified its gene structure. In order to analyze the regulatory sequence in the 5'-upstream region and introns, we carried out transient expression experiments of NSE genomic DNA fragments fused to chloramphenicol acetyltransferase (CAT) gene which were transfected into several cultured cells. The used cells were primary cultured rat neurons, PC12, neuroblastoma 35, neuroblastoma 103, C6, primary cultured rat glial cells and HeLa cells. The promoter sequence (190 bp) upstream to the transcription initiation site was important in the expression of CAT gene in these cells. From the experiments with external and internal deletion mutants of the fusion gene, the cis-acting regulatory region responsible for the enhanced expression of the CAT activity in the primary cultured neuron and PC12 cells was found to be localized at upstream 500 bp sequence of the intron 1 and 1.5 kbp upstream sequence of the transcription initiation site. In the upstream important sequences, there were the nearest sequences for AP-1 binding motif, AP-2 binding element, SP-1 binding sequence, cAMP response element, half site of glucocorticoid receptor (GRE) binding sequence, half site of thyroid hormor receptor (TR) or retinoic acid receptor (RAR) binding sequence and MTF-1 binding sequence. Furthermore, Octamer-6 binding motifs also were found. In the intron 1, 5' end upstream 50 bp and downstream 100 bp were the most important sequences. We found the nearest sequences for cAMP response element, E2F binding sequence, early growth response (EGR)-1 binding motif, half site of TCF-1 binding sequence and a neuron-specific element-like sequence in the intron 1.
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PMID:Upstream and intron regulatory regions for expression of the rat neuron-specific enolase gene. 770 74

RC3 encodes a thyroid hormone-dependent, calmodulin-binding, protein kinase C substrate (neurogranin, p17) present in the dendritic spines of discrete neuronal populations in the forebrain. Its physiological role could be related to synaptic plasticity, memory, and other processes. In the present work we have isolated and sequenced 2.4 kbp of genomic DNA upstream from the origin of transcription and determined its nucleotide sequence. The major features of the RC3 promoter are the absence of TATA and CAAT boxes and the presence of an Initiator sequence surrounding the cap site. By sequence analysis we identified several cis-acting regulatory elements, among them response elements for retinoic acid and steroid (glucocorticoids/progesterone) hormone receptors. An oligonucleotide containing the retinoic acid responsive element bound to retinoic acid receptors specifically in vitro and conferred retinoic acid regulation to a heterologous promoter after transfection in COS-7 cells. Retinoic acid and dexamethasone, respectively, increased activity of the RC3 promoter in neuroblastoma cells when a deletion construct containing the retinoic acid and the glucocorticoid responsive elements was cotransfected with retinoic acid receptor or glucocorticoid receptor expression vectors. When added together all-trans retinoic acid and dexamethasone had additive effects. Despite the fact that RC3 expression in vivo is thyroid hormone-dependent, no evidence for the presence of a thyroid hormone responsive element was found within the 2.4 kbp flanking region analyzed and thyroid hormone did not increase reporter activity after cotransfection of suitable constructs with thyroid hormone receptor expression vectors. Our results suggest that the expression of RC3 in vivo could be subject to complex physiological signals, including retinoids and steroid hormones in addition to thyroid hormones.
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PMID:Characterization of the promoter region and flanking sequences of the neuron-specific gene RC3 (neurogranin). 789 4

In the mammalian central nervous system, responsiveness to glucocorticoids is mediated by both the mineralocorticoid receptor (MR) and the glucocorticoid receptor (GR). These pharmacologically distinct receptors are believed to bind to common response elements as homodimers. We provide evidence that MR and GR can form a heterodimeric complex with DNA-binding and transactivation properties different from those of the respective homodimers. There was a high degree of cooperativity of MR and GR in binding to a glucocorticoid response element. Transient transfection of a neuroblastoma cell line revealed a transcriptional response pattern of coexpressed MR and GR distinct from that obtained by MR or GR alone. Our findings demonstrate that heterodimerization of MR and GR is a hitherto unrecognized principle for the transcriptional regulation of glucocorticoid-responsive genes in tissue coexpressing these receptors.
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PMID:Heterodimerization between mineralocorticoid and glucocorticoid receptor: a new principle of glucocorticoid action in the CNS. 799 37

Neuronal-type nitric oxide synthase (NOS I) is involved in ischemia-induced brain damage, and glucocorticoids have been reported to protect from brain damage. This prompted us to investigate if the activity or expression of NOS I was influenced by glucocorticoids. We used the murine neuroblastoma cell line N1E-115 as our experimental model. Short-term incubation (30 min) of the N1E-115 cells with dexamethasone (10 nM to 1 microM) or hydrocortisone (100 nM to 10 microM) did not change the enzymatic activity of NOS I. However, the glucocorticoids inhibited NOS I mRNA expression in a concentration-dependent fashion (down to 53.3 +/- 2. 5% of control). In time-course experiments with 100 nM dexamethasone, maximum down-regulation of NOS I mRNA was seen after 24 hr (55.6 +/- 6.3% of control). Similar effects were seen with 10 microM hydrocortisone. The effect of 100 nM dexamethasone was completely reversed by 1 microM of the glucocorticoid receptor antagonist mifepristone. In experiments with actinomycin D (10 microg/ml), the half-life of the NOS I mRNA was determined to be approximately 12 hr and remained unchanged after glucocorticoid incubation. Nuclear run-on analyses indicated that the decrease in NOS I mRNA was the result of a glucocorticoid-induced inhibition of NOS I gene transcription. In Western blots, the 160-kDa NOS I protein band was down-regulated to 68.5 +/- 8.4% of control after an incubation of the N1E-115 cells with 100 nM dexamethasone for 26 hr. Similarly, NO production was down-regulated to 57.8 +/- 8.7% of control. These data demonstrate that glucocorticoids reduce the expression of NOS I without changing its activity.
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PMID:Expressional down-regulation of neuronal-type nitric oxide synthase I by glucocorticoids in N1E-115 neuroblastoma cells. 968 66

Rifampicin, an antibiotic widely used in tuberculosis therapy, is known to exert psychotropic side effects in some patients. Recently, rifampicin has been reported to activate the glucocorticoid receptor (GR) in human hepatocytes. Because there is evidence that increased levels of glucocorticoids may induce cognitive impairment, sometimes culminating in depression, the side effects of rifampicin may result from GR activation in central nerve cells. Therefore, we used reporter gene assays to determine whether rifampicin displays glucocorticoid-like effects in human neuroblastoma SK-N-MC cells or mouse hippocampal HT22 cells. Rifampicin was unable to elicit any detectable transactivation of GR in both cell types, whereas cortisol or dexamethasone led to a potent transcriptional response. Rifampicin was also inactive in the same HepG2 cell line that was originally used to demonstrate the effect of rifampicin on GR. Moreover, rifampicin was unable to compete with dexamethasone for binding to GR. Finally, by blocking the multidrug resistance P-glycoprotein transporter (a xenobiotic extrusion pump) with verapamil or cyclosporin A, we excluded the possibility that the lack of effect by rifampicin was due to its export from the cell. Our results establish that rifampicin does not activate GR, and rule out the hypothesis that the psychotropic side effects of rifampicin treatment are a consequence of GR activation.
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PMID:Rifampicin is not an activator of glucocorticoid receptor. 1072 19

The tumour suppressor p53 and the glucocorticoid receptor (GR) respond to different types of stress. We found that dexamethasone-activated endogenous and exogenous GR inhibit p53-dependent functions, including transactivation, up- (Bax and p21(WAF1/CIP1)) and down- (Bcl2) regulation of endogenous genes, cell cycle arrest and apoptosis. GR forms a complex with p53 in vivo, resulting in cytoplasmic sequestration of both p53 and GR. In neuroblastoma (NB) cells, cytoplasmic retention and inactivation of wild-type p53 involves GR. p53 and GR form a complex that is dissociated by GR antagonists, resulting in accumulation of p53 in the nucleus, activation of p53-responsive genes, growth arrest and apoptosis. These results suggest that molecules that efficiently disrupt GR-p53 interactions would have a therapeutic potential for the treatment of neuroblastoma and perhaps other diseases in which p53 is sequestered by GR.
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PMID:Negative cross-talk between p53 and the glucocorticoid receptor and its role in neuroblastoma cells. 1108 Jan 52

Cyclooxygenases-1 and -2 are both expressed in neuronal cells in vivo. In the neuroblastoma cell lines NG108 and N2a, however, only cyclooxygenase-1 was detectable. Differentiation of the cells with retinoic acid increased cyclooxygenase-1 mRNA and protein expression within 24 and 48 h, respectively. A further increase was observed when the cells were concomitantly treated with the glucocorticoid dexamethasone (a 2-3-fold increase compared with retinoic acid alone). In the absence of retinoic acid, dexamethasone only slightly up-regulated cyclooxygenase-1 expression. The inhibitor of protein synthesis cycloheximide abrogated the effect of dexamethasone, indicating the involvement of newly synthesised proteins. Retinoic acid increased the transcription of cyclooxygenase-1 mRNA, determined with a luciferase-coupled promoter construct. Dexamethasone only slightly augmented cyclooxygenase-1-promoter activity but increased cyclooxygenase-1 mRNA stability. Other corticosteroids, hydrocortisone and aldosterone, also up-regulated cyclooxygenase-1 whereas neurosteroids or oestrogen were ineffective. Up-regulation was mediated primarily by the glucocorticoid receptor, because the receptor antagonist RU486 strongly reduced the effects of all corticosteroids. This indicated that in NG108 cells, the mineralocorticoid aldosterone may bind to the glucocorticoid receptor. Treatment of NG108 or N2a cells with corticosteroids did not alter the morphological phenotype obtained during differentiation. We thus show that corticosteroids, which down-regulate cyclooxygenase expression in most cell types, up-regulate cyclooxygenase-1 during neuronal differentiation.
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PMID:Up-regulation of cyclooxygenase-1 in neuroblastoma cell lines by retinoic acid and corticosteroids. 1129 4

Cisplatin is an antineoplastic drug that binds to DNA, thereby inhibiting cell division and tumor growth. Cisplatin may also disrupt the function of some proteins, including heat shock protein 90 (Hsp90). We report that cisplatin dose-dependently inhibited transcriptional activity of the androgen receptor and the glucocorticoid receptor (GR) in transient reporter assays. A truncated, hormone-independent GR was only partially inhibited at significantly higher doses of cisplatin. Cisplatin treatment of neuroblastoma cells led to an immediate inhibition of hormone binding by GR, followed by proteasome-dependent degradation of the receptor. Other Hsp90-regulated proteins, i.e. the phosphokinases raf-1, lck, and c-src, were not affected, indicating a specific functional interference of cisplatin with the steroid receptors GR and androgen receptor. Cisplatin did not elicit a stress response, in contrast to geldanamycin. Immunoprecipitation revealed that cisplatin disrupts binding of GR to Hsp90. Moreover, cisplatin-treated Hsp90 was unable to associate with untreated ligand binding domain of GR. Reticulocyte lysate was able to restore hormone binding of GR in vitro, but not when the lysate was pretreated with geldanamycin. Our data reveal that cisplatin influences steroid receptors also independently of its DNA-mediated effects and, thus, suggest a novel modes of action for this cytostatic drug.
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PMID:The heat shock protein 90-targeting drug cisplatin selectively inhibits steroid receptor activation. 1286 91

Corticosteroid actions in the brain are exerted via the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR). These receptors share several structural and functional similarities but their activation in the brain triggers distinct biological actions, for instance on neuronal survival or the regulation of the hypothalamo-pituitary-adrenal axis. Like other hormone-activated receptors, the transcriptional properties of the MR and GR depend on their ability to recruit a variety of co-regulators, which modulate their activity on target promoters, in a specific manner. The N-terminal regions of the MR and GR share the smallest degree of sequence conservation, whereas they display opposite effects on the transactivation properties of these receptors; thus, they may provide surfaces suitable for receptorspecific interactions with co-regulatory proteins. Here, we employed a yeast two-hybrid system to identify molecules interacting with the N-terminal part of the MR (amino acids 170-433). This approach resulted in the isolation of representative cDNAs from all members of the protein inhibitor of activated STAT (PIAS) family of proteins as potential MR-interacting partners. In neural cells, PIAS3 exhibited a strong and specific interaction with MR, but not GR, as indicated by mammalian two-hybrid assays and co-immunoprecipitation experiments in vivo. The interaction with MR was enhanced in the presence of aldosterone, an MR agonist, and was found to occur through a conserved, serine- and acidic amino acid residue-rich domain of PIAS3. To compare the modulatory properties of PIAS proteins on MR and GR transcriptional activity in a neural environment, MMTV reporter gene assays were performed in the human neuroblastoma cell line SK-N-MC. This analysis revealed that PIAS3 can inhibit MR, but not GR, transactivation in response to their corresponding ligands. Further, it showed that PIAS1 and PIASxbeta, but not PIASy, could also inhibit MR-mediated transcription despite the lack of detected physical interaction with MR. Interestingly, PIASxbeta and PIASy dose-dependently co-activated GR, whereas PIAS1 impaired GR-induced transcription. Taken together the results reveal differential modulatory roles of the PIAS proteins on the transcriptional properties of MR and GR, thus providing new insights into the bifurcating actions of these two receptors in neural cells where they are frequently co-localized.
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PMID:The manifold actions of the protein inhibitor of activated STAT proteins on the transcriptional activity of mineralocorticoid and glucocorticoid receptors in neural cells. 1517 15


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