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)

Alz-50, a monoclonal antibody originally prepared using Alzheimer brain homogenates, reacts with PHF-tau and normal tau on immunoblots, and stains specific neuronal populations in sections from Alzheimer's disease brain. Although the Alz-50 epitope has been mapped to amino acids 2-10 present in all human tau isoforms, minimal Alz-50 immunoreactivity is present in tissue from control brain, suggesting Alz-50 binding may be dependent on tau conformational differences. The absence of conclusive results concerning Alz-50 binding presents the possibility of Alz-50 immunoreactivity with proteins other than tau. The present study demonstrates Alz-50 cross-reactivity with denatured bovine serum albumin (BSA) and human serum albumin (HSA). Using LA-N-5 neuroblastoma cells, BSA from serum-containing media was present in cell homogenates and was found to be Alz-50-reactive on immunoblots. In fact, Alz-50 (0.1 microgram/ml) recognized as little as 78 ng of BSA and 312 ng of HSA. Since Alz-50 does not recognize native BSA, blocking of immunoblots with 3% BSA did not alter Alz-50 reactivity with tau from LA-N-5 cells. On SDS-polyacrylamide gels, HSA (approximately 69 kDa) migrates very closely to the pattern of A68 (PHF-tau) from Alzheimer brain homogenates. Hence, the presence of BSA or other albumins in cell or brain homogenates may be an important concern when using the Alz-50 antibody.
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PMID:Monoclonal antibody Alz-50 reacts with bovine and human serum albumin. 753 57

The localization and phosphorylation state of tau in LA-N-5 neuroblastoma cells was examined. Our results demonstrate that there are two populations of tau in LA-N-5 cells: cytosolic tau and nuclear tau. Indirect immunofluorescent microscopy revealed that nuclear tau is specifically localized to the nucleolus while cytosolic tau is diffusely distributed. To localize and quantitate tau in LA-N-5 cells by subcellular fractionation, a method was developed to extract tau from the nucleus while preserving the endogenous state of the protein. These studies revealed that 16% of the total tau protein in LA-N-5 cells is located in the nucleus and more specifically was found predominantly in the chromatin fraction containing DNA, chromatin, and associated proteins. The phosphorylation state of nuclear and cytosolic tau was examined by labeling LA-N-5 cells with 32Pi and immunoprecipitating tau from the different fractions. These data demonstrated that nuclear tau and cytosolic tau are phosphorylated approximately to the same extent. To determine if the phosphorylation of nuclear tau occurs in the nucleus, LA-N-5 nuclei were isolated, incubated with [gamma-32P]ATP, extracted, and tau was immunoprecipitated. Although numerous nuclear proteins were 32P-labeled, tau was not phosphorylated. These results suggest that nuclear tau is not phosphorylated in the nucleus but rather in the cytosol prior to transport into the nucleus. The specific localization of nuclear tau strongly suggests that it has a functional role in the nucleus. However, further studies are necessary to determine the function of nuclear tau and how it may be regulated by phosphorylation.
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PMID:Localization and in situ phosphorylation state of nuclear tau. 755 41

1. SH-SY5Y, an adrenergic human neuroblastoma cell line, was used to examine the hypothesis that D-lysergic acid (LSD) affects the metabolism of microtubule-associated tau protein, thus affecting microtubule assembly and the transport of neurotransmitters. 2. After 48 hr treatment LSD (10(-5) and 10(-7) M) decreased 50 kDa tau protein in the membrane (pellet) fraction. The drug (10(-5) M) also decreased in the cytoplasmic (supernatant) fraction. 3. This reduction in tau protein was accompanied by a 65% increase (P < 0.05) in total protein after LSD (10(-7) M) in the cytoplasmic fraction.
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PMID:D-lysergic acid reduces microtubule-associated tau protein in SH-SY5Y human neuroblastoma cells. 755 48

In this study, the in situ phosphorylation and subsequent calcium-activated proteolysis of tau protein were examined in human neuroblastoma (LA-N-5) cells, which were differentiated into a neuronal phenotype. The phosphorylation of tau was increased by treating the cells with forskolin and rolipram, which elevate cyclic AMP levels, by treating with the phosphatase inhibitor okadaic acid, or by treating with a combination of both treatments. Phosphorylated tau migrated slightly slower on sodium dodecyl sulfate-polyacrylamide gels than tau from untreated cells. Immunostaining with the phosphate-sensitive monoclonal antibody Tau-1 was also decreased in cells treated with okadaic acid, indicating an increase in the phosphorylation of specific Ser-Pro motifs within the molecule. Calcium-dependent, in situ proteolysis of tau protein was induced by treating the cells with the calcium ionophore A23187. Tau protein was proteolyzed to a significantly lesser extent in cells treated with forskolin and rolipram, okadaic acid, or both than in cells in which phosphorylation was not increased. Partially purified tau protein from cells treated with a combination of forskolin, rolipram, and okadaic acid was also more resistant to proteolysis by calpain in vitro compared with tau isolated from control cells. These data suggest a possible role for phosphorylation in the regulation of tau metabolism and in pathological conditions in which the balance between protein kinases and phosphatases is disrupted.
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PMID:Phosphorylation of tau in situ: inhibition of calcium-dependent proteolysis. 761 52

Recently, a mitogen activated protein kinase has been implicated in the generation of a phosphorylated paired helical filament (PHF) epitope recognized by the monoclonal antibody AT8. This epitope consists of phosphorylated serines 199 and/or 202 of the human microtubule associated protein tau. Theoretically, aside from abnormal kinase activity, inhibition of phosphatase activity could also be involved in the abnormal phosphorylation status of the microtubule associated protein tau. To investigate this, we incubated LA-N-5 neuroblastoma cells with okadaic acid, a specific inhibitor of phosphatase 2A. We found that incubating neuroblastoma cells with okadaic acid induces the abnormally phosphorylated AT8 epitope. The effect of okadaic acid is time and dose dependent and is reversible. Our findings suggest that phosphatase activity is important in the regulation of the phosphorylation state of tau. Phosphatases may act directly on tau or may influence the activity of mitogen activated protein kinase. Incubation of LA-N-5 neuroblastoma cells with okadaic acid provides a cellular model in which the generation of a well-defined PHF-tau epitope can be investigated.
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PMID:The phosphatase inhibitor okadaic acid induces a phosphorylated paired helical filament tau epitope in human LA-N-5 neuroblastoma cells. 768 10

Human neuroblastoma cells, LAN, were used to study the phosphorylation and dephosphorylation of tau proteins. These cells contained mainly a form of tau comparable to fetal brain tau in molecular weight (55 kDa). Neuroblastoma tau reacted with antibodies that recognize epitopes spanning the whole tau molecule (E-1, Alz50, Tau-1, and Tau46), and antibodies (PHF-1, NP8, and T3P) that recognize hyperphosphorylated tau (PHF-tau) in Alzheimer's disease (AD) brains. Exposure of the cells to 45 degrees C heat stress resulted in dephosphorylation of the epitopes recognized by PHF-1, NP8, and T3P. Transfer of the heat-stressed cells to 37 degrees C led to rephosphorylation of the dephosphorylated epitopes. Cells that had been treated with okadaic acid (OA), regardless of whether they were subsequently subjected to heat stress or heat stress and recovery, all contained tau with a molecular weight similar to that of control cells. These tau proteins, similar to tau in control cells, also reacted with antibodies to phosphorylated epitopes. However, unlike the tau from control or heat-stressed cells, the OA-treated and heat-stressed tau had decreased reactivity with Tau-1. Alteration of Tau-1 immunoreactivity has been reported to be an early event in AD neurodegeneration. The reduction of Tau-1 immunoreactivity observed in OA-treated samples could be restored by incubation of electroblots of isolated tau with alkaline phosphatase, indicating an induction of the Tau-1 epitope phosphorylation by OA.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Reversible heat stress-related loss of phosphorylated Alzheimer-type epitopes in Tau proteins of human neuroblastoma cells. 769 94

1. Cultured human SH-SY5Y neuroblastoma cells were used to determine whether 17-beta-estradiol affects the metabolism of microtubular tau protein. 2. After 24-hr treatment 17-beta-estradiol (10(-7) M) increased 50 kDa tau protein in the cytoplasmic (supernatant) fraction and decreased it in the membrane (pellet) fraction. 3. The increase in cytoplasmic tau was accompanied by increases in total protein in both cytoplasmic and membrane fractions, 50 and 70%, respectively. 4. The estrogen (10(-7) M) also caused a 31% reduction in the total number of cells.
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PMID:Changes in microtubular tau protein after estrogen in a cultured human neuroblastoma cell line. 790 61

The in vitro phosphorylation of the microtubule-associated protein tau by casein kinase II was studied. Purified human brain tau was phosphorylated by casein kinase II to a stoichiometry of 0.7 mol of 32P/mol of tau. Individual recombinant human tau isoforms were phosphorylated to stoichiometries ranging from 0.2 to 0.8 mol of 32P/mol of tau. Casein kinase II catalyzed a 4-fold greater incorporation of phosphate into the tau isoform containing a 58-amino acid insert near its amino terminus (T4L) than the isoforms without the 58-amino acid insert (T3 and T4). Phosphopeptide mapping of casein kinase II phosphorylated human tau and recombinant tau isoforms suggested that the isoforms containing an amino-terminal insert constitute the major substrates for casein kinase II within the tau family. The sites of phosphorylation on T4L were identified by digesting phosphorylated T4L with the protease Asp-N, separating the peptides by reversed phase high performance liquid chromatography, and analyzing the isolated peptides by liquid-secondary ion mass spectrometry and solid-phase amino-terminal sequencing. Thr39 was identified as the predominant phosphorylation site, which is located 5 residues from the amino-terminal insert in T4L. Phosphopeptide mapping of tau isolated from LA-N-5 neuroblastoma cells indicates that Thr39 is phosphorylated in situ. To our knowledge, this is the first demonstration of a differential phosphorylation of the human tau isoforms, with the isoforms containing the acidic amino-terminal insert being the preferred substrates of casein kinase II.
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PMID:Casein kinase II preferentially phosphorylates human tau isoforms containing an amino-terminal insert. Identification of threonine 39 as the primary phosphate acceptor. 830 7

Previous studies indicated that a chemically-defined, differentiation medium (DM) induces neuroblastoma cells, especially IMR32K cells, to exhibit phenotypes of mature neurons (including neurite outgrowth and synthesis of neurofilament polypeptides) and develop certain attributes of the neurons which are affected by neurofibrillary degeneration in Alzheimer's disease, such as expression of tangle-associated epitopes and accumulation of paired helical filaments-(PHF-) like fibrils. Immunocytochemical staining suggested that this cytoskeletal abnormality most likely results from altered expression of tau proteins. In the current study, we addressed this issue by analyzing tau-enriched preparations of IMR32K cells that were previously exposed to different incubation media using a panel of antibodies specific to tau and related microtubule-associated proteins. These cultured cells exhibited three groups of tau immunoreactivities which differ in molecular weight. Among them the level of high molecular weight tau (MW 90-112 kDa) was selectively augmented after DM incubation. The tau proteins produced in these neuron-like cells shared phosphorylated sites with PHF-tau and fetal tau, but differed from PHF-tau in their lack of the N-terminal insert which characterizes adult isoforms.
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PMID:Modulated induction of tau proteins in cultured human neuroblastoma cells. 891 3

1. A human neuroblastoma cell line, SH-SY5Y, was used to determine the effects of delta-9-tetrahydrocannabinol (THC) on microtubule-associated tau protein. 2. After 48-hr treatment, THC (10(-9) M) decreased 50 kD tau protein in the cytoplasmic (supernatant) fraction, and in the membrane (pellet) fraction the drug (10(-7) M) also decreased 50 kD tau protein. 3. This reduction in tau protein was accompanied by a 27% reduction (P < 0.05) in the membrane (pellet) total protein after (10(-7) M) THC and a 28% increase (P < 0.02) in cytoplasmic (supernatant) total protein after 10(-9) M THC.
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PMID:Tau protein after delta-9-tetrahydrocannabinol in a human neuroblastoma cell line. 898 Oct 58


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