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)

Thyroid hormone (T3) has a multiplicity of effects on the developing nervous system. We have investigated T3 action using a cholinergic neuroblastoma cell line (S-20Y) as a model. S-20Y contains a nuclear receptor for T3 with binding properties similar to those of other T3 target tissues. In addition, these cells can carry out 5'-deiodination, which is necessary to produce active thyroid hormone in vivo. The enzyme involved in this process appears to be a type I deiodinase, based on its reaction kinetics and its susceptibility to inhibition by propylthiouracil. S-20Y cells maintained in T3-depleted medium showed decreased choline acetyltransferase (ChAT) activity. ChAT activity was restored to the control level in a dose-dependent manner by T3 repletion. Neither cell density nor viability was influenced by the hypothyroid state. The presence of a T3 receptor and the enzyme activity for T3 production, together with an effect of T3 on ChAT activity, demonstrate that S-20Y cells are a target for T3 action and suggest that these cells represent an excellent model system for studies of T3 effects on nervous tissues.
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PMID:Thyroid hormone actions on a cholinergic neuroblastoma cell line (S-20Y). 376 Aug 76

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

Neurotrophins are responsible for the differentiation and survival of neurons in the developing and in the adult nervous system. They bind to specific membrane receptors with tyrosine kinase activity whose prototype is the product of the trkA proto-oncogene. TrkB, a member of this family, is the receptor for the neurotrophins brain derived growth factor (BDNF) and neurotrophins-3, -4/5. In this study, we show that stable expression of the c-erbA proto-oncogene, which encodes the alpha 1-isoform of the nuclear receptor for thyroid hormone (Tr alpha 1) induces the expression of trkB mRNA with a concomitant decrease to undetectable levels of trkA and trkC mRNAs in the mouse neuroblastoma N2a cell line. trkB induction by c-erbA is ligand independent, since addition of T3 had no effect. The induced trkB transcript encodes a functional gp145trkB protein, which is phosphorylated on tyrosine in response to BDNF. Furthermore, induction of trkB mRNA is also caused by transient expression of either TR alpha 1 or beta 1 isoforms. Our results are compatible with the idea that there are certain pathways which are under control of unliganded thyroid hormone receptor, and that one of these pathways results in regulation of trk expression.
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PMID:Unliganded c-erbA/thyroid hormone receptor induces trkB expression in neuroblastoma cells. 813 11

To determine the functions of the alpha 1 and beta 1 thyroid hormone receptors (TRs) in neural differentiation, we have established stable transfected neuronal cell lines (Neuro-2a) that overexpress either TR alpha 1 or TR beta 1. 3,5,3'-Triiodothyronine (T3) treatment of cells that overexpress TR beta 1 blocks proliferation by an arrest of cells in G0/G1 and induces morphological and functional differentiation of Neuro-2a cells as indicated by the marked increase in the number of perisomatal filopodia-like neurites and in acetylcholinesterase (AChE) activity. The effect on AChE activity was dose-dependent, and the time-course analysis reveals that this effect occurs after 24 hr of T3 treatment, with a maximal increase occurring after 48 hr of treatment. The increase of AChE activity is paralleled by an increase of AChE mRNAs. Last, we present evidence that shows that the effects of T3 on differentiation are independent of its effect on proliferation. T3 had no effect on the differentiation of Neuro-2a cells that overexpressed TR alpha 1. Our results indicate that TR beta 1 may play a key role in the effects of T3 in neuroblastoma cell differentiation.
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PMID:Overexpression of the beta 1 thyroid receptor induces differentiation in neuro-2a cells. 814 69

Thyrotropin releasing hormone (TRH) gene is regulated negatively at the transcriptional level by thyroid hormone (T3) in rat anterior hypothalamus. The actions of T3 upon other target genes are known to be mediated through the thyroid hormone receptors (TR), TR alpha and TR beta. To explore whether the inhibitory regulation of human (h) TRH gene transcription by T3 is TR isoform specific and whether TRH gene transcription can be modulated as well by unliganded TR isoforms, transient gene expression studies have been carried out using hTRH-luciferase (TRH-Luc) chimeric constructs and TR expression constructs, co-transfected into a human neuroblastoma cell line (HTB-11). Data herein demonstrate T3-dependent inhibitory regulation of the hTRH gene promoter by TR-T3 complexes. Moreover, significant inhibition (39%-60%) could be achieved by T3 bound to either hTR alpha 1, hTR beta 1, or rTR beta 1, beta 2 and was comparable quantitatively, indicating an absence of TR isoform specificity for T3 inhibition. Conversely, basal promoter activity of the hTRH gene could be activated significantly by unliganded hTR alpha 1, beta 1, rTR beta 1, and beta 2 (150% to 334%), but not by hTR alpha 2. Thus, TRs appear to exert opposite effects on hTRH gene transcription, depending on the presence or absence of ligand (T3). These dual effects of TR suggest that the addition of the T3 ligand effects conformational changes that can abrogate the initiation of transcription.
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PMID:Ligand (T3) dependent and independent effects of thyroid hormone receptors upon human TRH gene transcription in neuroblastoma cells. 816 84

The effects of the thyroid hormone triiodothyronine (T3), nerve growth factor (NGF) and stress (exposure to heat or aluminum sulfate) on growth, development and ageing of human neuroblastoma cells were studied in vitro. Differentiation of cells using retinoic acid and NGF inhibits cell growth and proliferation; simultaneously, it promotes acquisition of neuronal phenotype, down-regulation of T3 receptors, and an increase in catecholaminergic tyrosine hydroxylase activity and microtubule assembly. The actions of T3 on neuronal differentiation resemble those of NGF and suggest the existence of NGF-T3 interactions. Exposure to stress inhibits cell growth and proliferation, increases immunoreactivity to the microtubule-assembling protein tau (which occurs in paired filaments of neurofibrillary tangles in the aged human brain), and facilitates formation of tau-ubiquitin complexes (which also occur in the aged brain). Stress does not prevent the inhibition of cell proliferation by high doses of T3; however, T3 doses that are equivalent to physiological levels reduce stress-induced inhibition of growth. Previous studies have shown that stress may also induce in these cells facsimile lesions of normal and abnormal ageing, such as accumulation of lipofuscin pigments, formation of paired helical filaments and increased immunoreactivity to tau, beta-amyloid proteins, and ubiquitin. These lesions may represent cellular and molecular manifestations of increased vulnerability and susceptibility to genetic and extrinsic factors (e.g. hormones and environmental influences) with ageing. It is proposed that neuroblastoma cells may serve as a model to study mechanisms of neuronal ageing and to identify agents and conditions capable of preventing, delaying or reducing metabolic abnormalities leading to age-associated disorders.
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PMID:Alterations in the growth and protein content of human neuroblastoma cells in vitro induced by thyroid hormones, stress and ageing. 839 Oct 82

The thyrotropin-releasing hormone (TRH) gene is regulated negatively at the transcriptional level by thyroid hormone (T3). T3 positive regulatory effects on other target genes, such as the growth hormone gene, are mediated through heterodimerization of thyroid hormone receptors (TRs) with RXR or other auxiliary nuclear protein(s). To explore whether an accessory co-suppressor protein(s) may be involved in T3 inhibitory regulation of human TRH gene transcription, transient gene expression studies have been carried out using a hTRH-luciferase (TRH-Luc) chimetric reporter construct, an hTR beta 1 expression construct, and pABgal-hTR beta 1 ligand-binding domain (LBD) fusion constructs, cotransfected into a human neuroblastoma cell line (HTB-11,ATCC). Results herein indicate that T3-dependent inhibitory regulation (48-60% of control) of the hTRH gene promoter by hTR beta 1-T3 complexes could be abrogated completely by cotransfection of a 10 x excess of hTR beta 1-LBD (TR 168-456 aa) in a pABgal94 vector. In striking contrast, cotransfection of a 10 x excess of highly truncated hTR beta 1-LBD (TR 452-456 aa) failed to reverse T3-mediated TRH promoter inhibition. This squelching effect by excessive intact TR-LBD, moreover, could not be reversed by raising T3 concentration 100-fold (from 10(-8) to 10(-6) M), thus excluding a squelching effect of T3 itself by excess LBD. These results suggest that negative regulation of the hTRH gene promoter activity by TR beta 1-T3 complexes involves interactions with an accessory co-suppressor protein, which may bridge DNA-bound TR beta 1-T3 complexes to the transcriptional initiation complex.
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PMID:Reversal of TR-T3 inhibition of the hTRH gene by excess TR ligand-binding domain: evidence for novel accessory protein. 883 32

We describe 11 cases (8 females, 3 males) of papillary thyroid carcinoma in children treated at St. Jude Children's Research Hospital over a 33-year period, and review the literature. Ages ranged from 7-25 years (median, 16 years). Six patients had primary papillary thyroid carcinoma. Five patients had secondary papillary thyroid carcinoma after treatment of Hodgkin's disease (n = 2), acute lymphoblastic leukemia (n = 2), and neuroblastoma (n = 1) with chemotherapy and cervical radiation. The typical presentation was either cervical lymphadenopathy or a thyroid mass of short duration. Treatment consisted of thyroidectomy, cervical lymph node dissection, and postoperative thyroid hormone replacement (n = 1), parathyroid reimplantation (n = 1), 131I ablation (n = 4), external-beam irradiation (n = 1), and chemotherapy with doxorubicin (n = 1) or carboplatin and topotecan (n = 1). Nine patients are alive without evidence of disease 3.0-22.4 years from diagnosis. One patient has persistent but stable disease 17.3 years after diagnosis. One patient relapsed with metastatic lung disease 0.3 years after the initial diagnosis. He continues to do well after a brief but unsustained complete radiographic remission of disease to combination chemotherapy with carboplatin and topotecan. Our review supports excellent long-term outcome for primary or secondary papillary thyroid carcinoma in pediatric patients although complications may require close follow-up in a multidisciplinary setting.
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PMID:Papillary thyroid carcinoma: demographics, treatment, and outcome in eleven pediatric patients treated at a single institution. 914 89

TRH is negatively regulated by T3 both in the hypothalamic paraventricular nucleus and transient transfection models. Mutations in hTR beta 1 genes are associated with the syndrome of generalized resistance to thyroid hormone. To investigate potential effects of mutant TRs on T3 regulation of the hTRH gene, transient gene expression assays were performed in human neuroblastoma (HTB-11) cells with an hTRH promoter-luciferase construct, wild type (WT) hTR beta 1, and three qualitatively distinct hTR beta 1 mutant forms (ED, OK and PV). In the presence of T3 (10(-9) M), liganded WT-hTR beta 1 inhibited hTRH promoter activity significantly (40%). Cotransfection of each of the two mutants (ED and OK) achieved similar levels of inhibition only at 10 to 100 fold increased T3 concentrations. Of interest, a 10x excess of mutant ED or OK could also exert dominant negative effects upon WT hTR beta 1-T3 mediated inhibitory actions on the hTRH promoter. In contrast, mutant TR-PV exerted neither inhibitory nor dominant negative effects at even higher concentrations of T3. Moreover, all three unliganded mutant forms stimulated TRH promoter activity significantly in the absence of T3, despite their different mutations in the ligand-binding domain (LBD). These data demonstrate that thyroid hormone resistance at the level of TRH gene regulation, due to reduced inhibitory actions of mutant TR-T3 complexes, as well as dominant negative effects upon WT hTR beta 1 mediated inhibition, likely contribute to elevated TSH values observed in the syndrome of thyroid hormone resistance.
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PMID:Regulation of the human TRH (hTRH) gene by human thyroid hormone receptor beta 1 (hTR beta 1) mutants. 943 Aug 20

The beta-amyloid protein (Abeta), the major component of the senile plaques found in Alzheimer brains, derives from a larger beta-amyloid precursor protein (APP). Alternative splicing of the APP gene yields three major APP messenger RNAs (mRNAs), which, in turn, give rise to the APP770, APP751, and APP695 protein isoforms. In this study we examined the effects of thyroid hormone on APP expression in N2a-beta neuroblastoma cells. T3 caused a significant increase in the APP770 mRNA band, in detriment of the APP695 mRNA, which was proportionately reduced. In agreement with these results, T3 markedly altered the relative ratio of intracellular APP isoforms, increasing the amount of APP770 and causing an equivalent reduction of the immature APP695 isoform. In accordance with these results, the soluble APP695-derived form was specifically reduced in the culture medium obtained from T3-treated cells. In contrast, the increase in intracellular APP770 was not followed by an enhanced release of soluble derivatives of this isoform. These results suggest that T3 regulates not only APP gene splicing, but also the processing and secretion of the APP peptides. According to our results, thyroid hormone might play a role in the development of Alzheimer's disease by modulating the intracellular and extracellular contents of APP isoforms.
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PMID:Thyroid hormones regulate beta-amyloid gene splicing and protein secretion in neuroblastoma cells. 960 74


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