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)

Iron-responsive elements (IREs) are the RNA stem loops that control cellular iron homeostasis by regulating ferritin translation and transferrin receptor mRNA stability. We mapped a novel iron-responsive element (IRE-Type II) within the 5'-untranslated region (5'-UTR) of the Alzheimer's amyloid precursor protein (APP) transcript (+51 to +94 from the 5'-cap site). The APP mRNA IRE is located immediately upstream of an interleukin-1 responsive acute box domain (+101 to +146). APP 5'-UTR conferred translation was selectively down-regulated in response to intracellular iron chelation using three separate reporter assays (chloramphenicol acetyltransferase, luciferase, and red fluorescent protein reflecting an inhibition of APP holoprotein translation in response to iron chelation. Iron influx reversed this inhibition. As an internal control to ensure specificity, a viral internal ribosome entry sequence was unresponsive to intracellular iron chelation with desferrioxamine. Using RNA mobility shift assays, the APP 5'-UTRs, encompassing the IRE, bind specifically to recombinant iron-regulatory proteins (IRP) and to IRP from neuroblastoma cell lysates. IRP binding to the APP 5'-UTR is reduced after treatment of cells with desferrioxamine and increased after interleukin-1 stimulation. IRP binding is abrogated when APP cRNA probe is mutated in the core IRE domain (Delta4 bases:Delta83AGAG86). Iron regulation of APP mRNA through the APP 5'-UTR points to a role for iron in the metabolism of APP and confirms that this RNA structure can be a target for the selection of small molecule drugs, such as desferrioxamine (Fe chelator) and clioquinol (Fe, Cu, and Zn chelator), which reduce Abeta peptide burden during Alzheimer's disease.
 ...
PMID:An iron-responsive element type II in the 5'-untranslated region of the Alzheimer's amyloid precursor protein transcript. 1219 35

To study the transcriptional mechanisms by which expression of the dopamine receptor regulating factor (DRRF) gene is regulated, a murine genomic clone was isolated using a DRRF cDNA as probe. A 24 kb genomic fragment which comprises 13 kb upstream of the transcription initiation site was sequenced. The promoter region lacks a TATA box and CAAT box, is rich in G+C content, and has multiple putative binding sites for the transcription factor Sp1. The DRRF gene also has consensus sequences for AP1 and AP2 binding sites. The transcriptional activity of five deletion mutants of a 1.5 kb fragment was analyzed by modulating transcription of the heterologous chloramphenicol acetyltransferase (CAT) gene in the promoterless plasmid pCAT-Basic. All mutants showed significant transcriptional activity in the murine neuroblastoma cell line NB41A3, except the construct stretching from -901 to +17. These transient expression assays suggested the presence of positive regulators between -1153 and -901 and between -118 and -93 while a negative regulator was found in the region between -901 and -118. Comparison among cell types revealed strong transcriptional activity of the DRRF promoter in neuronal NB41A3 cells and moderate activity in hepatic HepG2 and renal OK cells, but none in skeletal muscle C2C12 or glial C6 cells. These findings confirm the tissue-specific activity of the DRRF promoter and suggest that this gene shares structural and functional similarities with the dopamine receptor genes that it regulates.
 ...
PMID:Genomic organization and promoter characterization of the murine dopamine receptor regulating factor (DRRF) gene. 1256 28

We have previously defined a crucial DNA element controlling 90% of the expression of the presenilin 1 gene at (-35 to +6). This region contains an Ets transcription factor binding motif, and a 2-base pair alteration within the core sequence (GGAA to TTAA) of the Ets consensus also reduced transcription by over 90%. We have shown that Ets1/2 transcription factors bind specifically to the -10 Ets element and activate PS1 transcription. The identification of other transcription factors recognizing specifically this promoter area should provide insights into the regulation of PS1. We have used the -10 Ets element as a bait in yeast one hybrid screening of a human brain cDNA library. This assay selected three factors from the Ets family: Ets2, ER81 and Elk1. We show that in vitro translated ER81 indeed binds specifically to the -10 region of the PS1 promoter and that ER81 activates by two- to threefold the basal transcription of a presenilin-1 promoter-chloramphenicol acetyltransferase reporter synthetic gene (-119, +178)PS1CAT in transient infection assays in neuroblastoma cells (SK-N-SH). GABPalpha, a member of the Ets family closely related to Ets2 and also containing a pointed domain, only increased PS1 transcription by about twofold. Cotransfection of GABPbeta together with GABPalpha did not increase PS1 transcription. However, GABPbeta alone activated PS1 transcription by two- to threefold. In contrast, the more distantly related Ets factor Elk1 repressed PS1 transcription very effectively.
 ...
PMID:Ets transcription factors ER81 and Elk1 regulate the transcription of the human presenilin 1 gene promoter. 1275 7

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.
 ...
PMID:Regulation of the human corticotropin-releasing-hormone gene promoter activity by antidepressant drugs in Neuro-2A and AtT-20 cells. 1473 30

Tyrosine hydroxylase (TH) is expressed specifically in catecholaminergic cells and is transcriptionally activated via a protein kinase C (PKC)-dependent pathway. To identify regulatory regions of the TH gene, transfected neural crest-derived catecholaminergic cells [human neuroblastoma SH-SY5Y and bovine adrenal medullary (BAM) cells] or glia-derived SF-763 cells were used to analyze expression of a chloramphenicol acetyltransferase (CAT) reporter gene under the control of 5'-flanking sequences of the bovine TH gene. Plasmid pTH(-245/+21)CAT was constructed by fusing the -245 to +21 region of the TH gene to CAT sequences in the promoterless pCAT basic plasmid. Cells transfected with pTH(-245/+21)CAT expressed CAT activity at levels 8- to 100-fold higher than those of cells transfected with pCAT basic. In SH-SY5Y or BAM cells, pTH(-245/+21)CAT supported the expression of CAT at levels similar to or higher than that supported by the tissue nonspecific viral SV40 promoter/enhancer. In glia-like cells, CAT expression from pTH(-245/+2 1)CAT was about 13-fold lower than that under the control of the SV40 promoter. Incubation of neuroblastoma cells with the active phorbol ester, phorbol 12-myristate 13-acetate (PMA), increased expression of CAT from pTH(-245/+2 1)CAT over 6-fold and was accompanied by induction of c-fos and c-jun mRNAs and proteins. The regulation of TH promoter function by c-Fos/c-Jun was corroborated by transactivation of the TH promoter in SH-SY5Y cells engineered to overexpress exogenous c-Fos and c-Jun. TH gene sequences essential for c-Fos/c-Jun transactivation were located in the -245 to -52 region, upstream from a CRE-like element. Gel mobility assays demonstrated binding of c-Fos-antigen(s) to the region of the TH promoter that supports activation by PMA and c-Fos/c-Jun. Temporal patterns of nicotinic agonist-stimulated induction of c-fos and TH mRNA are also consistent with a role for c-Fos in TH gene transcription. Our results demonstrate that the 5'-flanking region of the bovine TH gene operates as an authentic promoter capable (i) of directing cell-specific expression of a bacterial CAT gene and (ii) of conferring responsivity to PKC-stimulation. The results also suggest that the nuclear proteins c-Fos and c-Jun contribute to PKC pathway-mediated activation of the TH gene via direct interaction with the TH gene promoter. The activation of TH gene expression by PKC/c-Fos/c-Jun may serve as an additional or alternative mechanism to activation by the cAMP-CRE pathway.
 ...
PMID:A 5'-flanking region of the bovine tyrosine hydroxylase gene is involved in cell-specific expression, activation of gene transcription by phorbol ester, and transactivation by c-Fos and c-Jun. 1991 82

The regions upstream from the human N-myc gene were examined for both transcription and replication. The plasmids containing several N-myc regions linked to the bacterial chloramphenicol acetyltransferase (CAT) gene were transfected to human neuroblastoma IMR32 cells. The results indicated that the region spanning from the PstI to the BamHI site (N-mycP-B; about 800 bp adjacent to the RNA start site), possessed enhancer activity. Various segments of the N-myc gene, overlapping the transcriptional regulatory regions, were subcloned into pUC19, and the plasmids were transfected to IMR32 cells together with a hygromycin B resistance-expression vector. The transfected cells were cultured in the presence of hygromycin B to establish cell lines resistant to the drug. Among the cell lines obtained, only the cells co-transfected with pN-mycP-B, the region of which contains enhancer activity described above, harboured the replicated pN-mycB-P in an episomal state. The results of BrdU labelling followed by CsCl isopycnic centrifugation suggested that the pN-mycP-B replicated once per cell cycle (in S phase) in concord with the replication of chromosomal DNA. In an in vitro DNA replication system using the nuclear extract from IMR32 cells, pN-mycP-B functioned as an template DNA of replication. Deletions up to 200 bp in the N-mycP-B region did not abolish the replicating activity, regardless of the positions of deletion, but deletions of longer than 300 bp did. These results suggest that the replicating activity of the fragment upstream of the human N-myc gene requires certain length, as well as the specific sequences not yet determined.
 ...
PMID:Autonomously replicating sequences identified in transcriptional regulatory regions of human N-myc gene. 2155 20


<< Previous 1 2 3 4 5 6 7