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  • 1
    Electronic Resource
    Electronic Resource
    TAK1-mediated induction of nitric oxide synthase gene expression in glial cells (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 87 (2003), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Inflammatory cell signaling leading to transcriptional activation is primarily mediated by signal transduction via mitogen-activated protein kinase (MAPK) and NFκB pathways. A common upstream kinase that signals the activation of these pathways is TGFβ–activated kinase 1 (TAK1), which itself becomes activated in response to cytokines and upon engagement of a class of cell surface receptors involved in innate immunity, that is Toll-like receptors (TLRs) by bacterial and viral pathogens. This study directly tests the role of TAK1 in the induction of inducible nitric oxide (NO) synthase (iNOS) in glial cells, which represent immune-regulatory cells of the CNS, by transient transfection assays. Transfection of C-6 glia, primary astrocytes and a rat microglial cell line with TAK1 (but not its inactive form) along with its activator protein, TAK1-binding protein 1 (TAB1) resulted in a marked stimulation of a co-transfected rat iNOS promoter-reporter construct (iNOS-Luc). TAK1-induced iNOS-Luc activity was substantially inhibited by pharmacological inhibitors of the known downstream kinases, p38 MAPK and JNK (SB203580 and SP620125), and was almost completely blocked by co-expression of a phosphorylation mutant of IκB. TAK1/TAB1 also induced the production of NO and the expression of iNOS in microglial cells in a p38 MAPK-, JNK- and NFκB-dependent manner. The results of these studies provide evidence for an important role for TAK1-mediated intracellular signaling, via p38 MAPK, JNK and NFκB, in the transcriptional activation of iNOS in glial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2003.01998.x
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  • 2
    Electronic Resource
    Electronic Resource
    Induction of N-Glycosylation Activity in Cultured Embryonic Rat Brain Cells (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 50 (1988), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Developmental changes in protein N-glycosylation activity have been studied using cultures of dissociated fetal rat brain cells as an in vitro model system. These cultures undergo an initial phase of neurite outgrowth and cell proliferation (4–6 days in culture), followed by a period of cellular differentiation. N-Glycosylation activity has been measured by assaying the incorporation of [2-3H]-mannose into dolichol-linked oligosaccharides and glyco-protein over a period of 1–25 days in culture. This study revealed a marked induction of N-glycosylation activity beginning at approximately 1 week of culture. [2-3H]-Mannose incorporation into the oligosaccharide-lipid intermediate fraction and glycoprotein reached maximal values between 12 and 16 days of culture and declined thereafter. The major dolichol-linked oligosaccharide labeled by the brain cell cultures was shown to be Glc3Man9GlcNAc2 by HPLC analysis. Parallel incorporation studies with [3H]leucine showed that the increase in protein N-glycosylation was relatively higher than a concurrent increase in cellular protein synthesis observed during the induction period. Maximal labeling of glycoprotein corresponded to the period of glial differentiation, as indicated by a sharp rise in the marker enzymes, 2′,3′-cyclic nucleotide 3′-phosphohydrolase (an oligodendroglial marker) and glutamine synthetase (an astroglial marker). The results describe a developmental activation of the N-glycosylation pathway and suggest a possible relationship between N-linked glycoprotein assembly and the growth and differentiation of glial cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1988.tb02922.x
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  • 3
    Electronic Resource
    Electronic Resource
    Developmental Changes in Enzymes Involved in Dolichyl Phosphate Metabolism in Cultured Embryonic Rat Brain Cells (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 56 (1991), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The rates of synthesis of dolichol-linked oligosaccharide intermediates and protein N-glycosylation increased substantially during a developmental period corresponding to glial differentiation in primary cultures of embryonic rat brain. In this study developmental changes in three enzymes involved in dolichyl phosphate (Dol-P) metabolism have been examined by in vitro assays and correlated with the induction pattern for lipid intermediate synthesis and protein N-glycosylation. Dolichyl pyrophosphate (Dol-P-P) phosphatase activity was relatively low during the first 9 days in culture, but it increased significantly between days 9 and 25. Dol-P-P phosphatase did not change appreciably between days 22 and 30 in culture. A kinetic analysis of the developmental change in Dol-P-P phosphatase activity revealed that the Vmax increased 10-fold between days 4 and 22, and there was also a significant change in the apparent Km for Dol-P-P. Dolichol kinase activity increased during the period (9–15 days) when there was a significant induction in oligosaccharide-lipid synthesis and protein N-glycosylation, and then declined in parallel with lipid intermediate synthesis and protein N-glycosylation. Dol-P phosphatase activity was present at relatively low levels for the first 9 days in culture, but it increased steadily between days 9 and 30. A kinetic comparison of the activity in membrane fractions from brain cells cultured for 9 and 25 days indicated that there was a 10-fold increase in enzyme protein with unaltered affinity for Dol-P. The results suggest that elevated dolichol kinase activity enhances the rate of lipid intermediate synthesis, and subsequent reciprocal changes in dolichol phosphorylation-dephosphorylation are a regulatory factor in the deactivation of oligosaccharide-lipid synthesis, and consequently of protein N-glycosylation, during the period following glial differentiation in primary cultures of embryonic rat brain cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1991.tb02600.x
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  • 4
    Electronic Resource
    Electronic Resource
    Activation of Mitogen-Activated Protein Kinases in Oligodendrocytes (1996)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 66 (1996), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The proliferation and differentiation of oligodendrocyte progenitors are stringently controlled by an interacting network of growth and differentiation factors. Not much is known, however, about the intracellular signaling pathways activated in oligodendrocytes. In this study, we have examined the activation of mitogen-activated protein (MAP) kinase [also called extracellular signal-regulated protein kinases (ERKs)] in primary cultures of developing oligodendrocytes and in a primary oligodendrocyte cell line, CG4, in response to platelet-derived growth factor (PDGF) and basic fibroblast growth factor. MAP kinase activation was determined by an in-gel protein kinase renaturation assay using myelin basic protein (MBP) as the substrate. The specificity of MAP kinase activation was further confirmed by an immune complex kinase assay using anti-MAP kinase antibodies. Stimulation of oligodendrocyte progenitors with the growth factors PDGF and basic fibroblast growth factor and a protein kinase C-activating tumor promoter, phorbol 12-myristate 13-acetate, resulted in a rapid activation of p42mapk (ERK2) and, to a lesser extent, p44mapk (ERK1). Immunoblot analysis with anti-phosphotyrosine antibodies revealed an increased Tyr phosphorylation of a 42-kDa phosphoprotein band cross-reacting with anti-MAP kinase antibodies. The phosphorylation of p42mapk in PDGF-treated oligodendrocyte progenitors was preceded by a robust autophosphorylation of the growth factor receptor. Immunoblot analysis with anti-pan-ERK antibodies indicated the presence of ERK-immunoreactive species other than p42mapk and p44mapk in oligodendrocytes. The presence of some of the same pan-ERK-immunoreactive species and certain renaturable MBP kinase activities was also demonstrable in myelin preparations from rat brain, suggesting that MAP kinases (and other MBP kinases) may function not only during oligodendrogenesis but also in myelinogenesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1996.66051986.x
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  • 5
    Electronic Resource
    Electronic Resource
    Cholesterol Biosynthesis and Its Regulation in Dissociated Cell Cultures of Fetal Rat Brain: Developmental Changes and the Role of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 45 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Primary cultures of cells dissociated from fetal rat brain were utilized to define the developmental changes in cholesterol biosynthesis and the role of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in the regulation of these changes. Cerebral hemispheres of fetal rats of 15–16 days of gestation were dissociated mechanically into single cells and grown in the surface-adhering system. Cholesterol biosynthesis, studied as the rate of incorporation of [14C]acetate into digitonin-precipitable sterols, was shown to exhibit two distinct increases in synthetic rates, a prominent increase after 6 days in culture and a smaller one after 14 days in culture. Parallel measurements of HMG-CoA reductase activity also demonstrated two discrete increases in enzymatic activity, and the quantitative and temporal aspects of these increases were virtually identical to those for cholesterol synthesis. These data indicate that cholesterol biosynthesis undergoes prominent alterations with maturation and suggest that these alterations are mediated by changes in HMG-CoA reductase activity. The timing of the initial prominent peak in both cholesterol biosynthesis and HMG-CoA reductase activity at 6 days was found to be the same as the timing of the peak in DNA synthesis, determined as the rate of incorporation of [3H]thymidine into DNA. The second, smaller peak in reductase activity and sterol biosynthesis at 14 days occurred at the time of the most rapid rise in activity of the oligodendroglial enzyme, 2′:3′-cyclic nucleotide 3′-phosphohydrolase (CNP). These latter observations suggest an intimate relationship of the sterol biosynthetic pathway with cellular proliferation and with oligodendroglial differentiation in developing mammalian brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb04021.x
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  • 6
    Electronic Resource
    Electronic Resource
    Cytokine Induction of Inducible Nitric Oxide Synthase in an Oligodendrocyte Cell Line (1999)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 72 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : The induction of inducible nitric oxide synthase (iNOS) by proinflammatory cytokines was studied in an oligodendrocyte progenitor cell line in relation to mitogen-activated protein kinase (MAPK) activation and cytokine-mediated cytotoxicity. When introduced individually to cultures of CG4 cells, the cytokines, i.e., tumor necrosis factor-α (TNFα), interleukin-1 (IL-1), and interferon-γ (IFNγ), had either minimal (TNFα) or no (IL-1 and IFNγ) detectable stimulatory effect on the production of nitric oxide. However, combinations of these factors, in particular, TNFα plus IFNγ, elicited a strong enhancement of nitric oxide synthesis and, as revealed by western blot and RT-PCR analysis, the expression of iNOS. TNFα and IL-1 were able to activate p38 MAPK in a time- and dose-dependent manner and together showed a combinatorial effect. In contrast, IFNγ neither activated on its own nor enhanced the activation of p38 MAPK in response to TNFα and IL-1. However, a specific inhibitor of p38 MAPK, i.e., SB203580, inhibited the induction of iNOS in cytokine combination-treated cells in a dose-dependent manner, thereby suggesting a role for the MAPK cascade in regulating the induction of iNOS gene expression in cytokine-treated cells. Blocking of nitric oxide production by an inhibitor of iNOS, i.e., nitro-L-arginine methyl ester, had a minimal protective effect against cytokine-mediated cytotoxicity that occurred before the elevation of nitric oxide levels, thereby indicating temporal and functional dissociation of nitric oxide production from cell killing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0720472.x
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrogen Peroxide Activation of Multiple Mitogen-Activated Protein Kinases in an Oligodendrocyte Cell Line (1999)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 72 (1999), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract : Oxidative stress is known to induce cell death in a widevariety of cell types, apparently by modulating intracellular signalingpathways. In this study, we have examined the activation of mitogen-activatedprotein kinase (MAPK) cascades in relation to oxidant-induced cell death in anoligodendrocyte cell line, central glia-4 (CG4). Exposure of CG4 cells tohydrogen peroxide (H2O2) resulted in an increasedtyrosine phosphorylation of several protein species, including the abundantlyexpressed platelet-derived growth factor (PDGF) receptor and the activation ofthe three MAPK subgroups, i.e., extracellular signal-regulated kinase (ERK),p38 MAPK, and c-Jun N-terminal kinase (JNK). Dose-response studies showeddifferential sensitivities of PDGF receptor phosphorylation (〉1mM) and ERK/p38 MAPK (〉0.5 mM) and JNK (〉0.1mM) activation by H2O2. The activation of ERKwas inhibited by PD98059, a specific inhibitor of the upstream kinase, MAPK orERK kinase (MEK). H2O2 also activated MAPK-activatedprotein kinase-2, and this activation was blocked by SB203580, a specificinhibitor of p38 MAPK. The oxidant-induced cell death was indicated bymorphological changes, decreased3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide reduction, andDNA fragmentation. These effects were suppressed dose-dependently by the MEKinhibitor PD98059. The results demonstrate that H2O2 induces the activation of multiple MAPKs in oligodendrocyte progenitors and that the activation of ERK is associated with oxidant-mediated cytotoxicity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1999.0720112.x
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  • 8
    Electronic Resource
    Electronic Resource
    Investigations on Myelination In Vitro: Regulation of 2′,3′-Cyclic Nucleotide 3′-Phosphohydrolase by Thyroid Hormone in Cultures of Dissociated Brain Cells from Embryonic Mice (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 37 (1982), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The direct influence of l-3,3′,5-triiodothyronine (T3) on the development of 2′,3′-cyclic nucleotide 3′-phosphohydrolase (EC 3.1.4.37, CNPase) is demonstrated by using an in vitro culture system of dissociated embryonic mouse brain cells. Serum from a thyroidectomized calf, which contained low levels of T3 (31 ng/100 ml), and thyroxine, T4 (〈1 μg/ml), was used in the culture medium in place of normal calf serum (T3, 103 ng/100 ml; T4, 5.7 μg/ml) to render the culture responsive to exogenously added T3. The lower levels of enzyme activity observed in the presence of such a deficient medium could be restored to normal values by T3 supplementation. Half-maximal effect was obtained with 2.5 ± 10−9m-T3. Three days of hormone treatment resulted in the maximal stimulation of CNPase. T4 was less effective in inducing CNPase activity and the inactive analog of the hormone, reverse T3 (3,3′,5′-T3) was ineffective. The morphological appearance of the cells was characterized by deformed (smaller size and less in number) reaggregates in the cultures, lacking hormone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1982.tb12543.x
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  • 9
    Electronic Resource
    Electronic Resource
    Minocycline protects basal forebrain cholinergic neurons from mu p75-saporin immunotoxic lesioning (2004)
    Oxford, UK : Blackwell Science Ltd
    European journal of neuroscience 19 (2004), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Two prominent characteristics of Alzheimer's disease are basal forebrain cholinergic degeneration and neuroinflammation characterized by glial activation and the release of pro-inflammatory cytokines. Mu p75- saporin (SAP) is a novel immunotoxin that mimics the selective loss of basal forebrain cholinergic neurons and induces cognitive impairment in mice. We report that cholinergic cell loss in the medial septal nucleus and ventral diagonal band after i.c.v. injection of mu p75-SAP is accompanied by simultaneous activation of microglia and astrocytes in the basal forebrain region as well as significant memory loss. Consistent with a role of glial cells in the pathology of Alzheimer's disease, minocycline, a second-generation tetracycline with known anti-inflammatory and neuroprotective properties, attenuated mu p75-SAP-induced cholinergic cell loss, glial activation and transcription of downstream pro-inflammatory mediators. In addition to neuroprotection, minocycline treatment mitigated the cognitive impairment that appears to be a functional consequence of mu p75-SAP lesioning. The current study demonstrates that glial-related inflammation plays a significant role in the selective neurotoxicity of mu p75-SAP, and suggests that minocycline may provide a viable therapeutic option for degenerating cholinergic systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.0953-816X.2004.03439.x
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  • 10
    Electronic Resource
    Electronic Resource
    Expression of Hyaluronectin by C-6 Glial Cells at High Density (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 44 (1985), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Hyaluronectin, a brain glycoprotein that has been localized to the nodes of Ranvier in vivo and to oligodendrocytes in primary cultures of neonatal rat brain cells, was shown by using an unlabeled immunoperoxidase method to be present in C-6 glial cells grown to high density. The density-dependent expression of this glycoprotein is in accordance with the known properties of the glial stem cells, i.e., induction of differentiated properties such as 2′,3′-cyclic nucleotide-3′-phosphohydrolase, glutamine synthetase, S-100 protein, and glial fibrillary acidic protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-4159.1985.tb07174.x
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