GLORIA

GEOMAR Library Ocean Research Information Access

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Blackwell Science Ltd.  (1,403)
  • 2000-2004  (1,403)
  • 1
    Electronic Resource
    Electronic Resource
    Endothelins Regulate Arachidonic Acid Release and Mitogen-Activated Protein Kinase Activity in Schwann Cells (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Immortalized rat Schwann cells (iSC) express endothelin(ET) receptors coupled to inhibition of adenylyl cyclase and stimulation ofphospholipase C (PLC). These effects precede phenotypic changes and increasedDNA synthesis. We have investigated the role of ETs in the regulation ofarachidonic acid (AA) release and mitogen-activated protein kinases (MAPKs).Both ET-1 and ET-3 increased AA release in iSC. This effect was sensitive tothe phospholipase A2 (PLA2) inhibitorsE-6-(bromomethylene)tetrahydro-3-(1-naphthalenyl)-2H-pyran-2-oneand arachidonyl-trifluoromethyl ketone but was insensitive to inhibitors ofPLC or phospholipase D-dependent diacylglycerol generation. ET-1-dependent AArelease was also unaffected by removal of extracellular Ca2+ andblocking the concomitant elevation in [Ca2+]i,consistent with participation of a Ca2+-independentPLA2. Treatment of iSC with ETs also resulted in activation ofextracellular signal-regulated kinase, c-Jun-NH2-terminal kinase(JNK), and p38 MAPK. A cause-effect relationship between agonist-dependent AArelease and stimulation of MAPKs, but not the opposite, was suggested byactivation of JNK by exogenous AA and by the observation that inhibition ofMAPK kinase or p38 MAPK was inconsequential to ET-1-induced AA release.Similar effects of ETs on AA release and MAPK activity were observed incultures expanded from primary SC and in iSC. Regulation of these effectorsmay mediate the control of proliferation and differentiation of SC by ETsduring peripheral nerve development and regeneration.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0752316.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Tau Protein Is Hyperphosphorylated in a Site-Specific Manner in Apoptotic Neuronal PC12 Cells (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Alterations in the status of microtubules contribute tothe cytoskeletal rearrangements that occur during apoptosis. Themicrotubule-associated protein tau regulates microtubule dynamics and thus islikely to play an important role in the cytoskeletal changes that occur inapoptotic cells. Previously, we demonstrated that the phosphorylation of tauat the Tau-1 epitope was increased during neuronal PC12 cell apoptosis, andfurther that the microtubule binding of tau from apoptotic cells wassignificantly impaired because of altered phosphorylation. The fact that themicrotubule-binding capacity of tau from apoptotic cells was reduced to∼30% of control values indicated that sites in addition to those withinthe Tau-1 epitope were hyperphosphorylated during apoptosis. In this studyusing a combination of immunological and biochemical approaches, numeroussites were found to be hyperphosphorylated on tau isolated from apoptoticcells. Further, during apoptosis, the activities of cell division controlprotein kinase (cdc2) and cyclin-dependent kinase 5 (cdk5) were selectivelyand significantly increased. The association of these two protein kinases withtau was also increased during apoptosis. These findings are intriguing becausemany of the sites found to be hyperphosphorylated on tau during apoptosis arealso hyperphosphorylated on tau from Alzheimer's disease brain. Likewise,there are data indicating that in Alzheimer's disease the activities of cdc2and cdk5 are also increased.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0752346.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Inhibition of Aberrant and Constitutive Phosphorylation of the High-Molecular-Mass Neurofilament Subunit by CEP-1347 (KT7515), an Inhibitor of the Stress-Activated Protein Kinase Signaling Pathway (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Previous studies have implicated stress-activated proteinkinases (SAPKs) in aberrant phosphorylation of the high-molecular-massneurofilament subunit (NFH). We now present direct evidence for thisinvolvement using CEP-1347, a specific inhibitor of SAPK activation.Inhibition by this drug of stress-induced phosphorylation of NFH and themiddle-molecular-mass neurofilament subunit in the perikaryon of dorsal rootganglion (DRG) neurons paralleled the decrease in levels of activated SAPKsand was essentially complete at 1 μM CEP-1347. In addition, a rolefor SAPKs in the constitutive phosphorylation of NFH was demonstrated.Longterm treatment of unstressed DRG neurons with CEP-1347 lowered thesteady-state phosphorylation level of NFH in neurites. No such effect was seenin neurons treated with PD 098059, which blocks activation of extracellularsignal-regulated kinase 1/2. DRG neurites were shown to contain high basallevels of activated SAPKs. These included a 55-kDa SAPK whose activation wascompletely abolished at 0.05 μM CEP-1347 and a 45-kDa SAPK thatwas not affected by the drug. These results indicate that SAPKs are involvedin both stress-induced and constitutive phosphorylation of NFH. The differingresponses of SAPKs in neurites and cell bodies to CEP-1347 inhibition furthersuggest the presence of different signaling pathways in the two neuronalcompartments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0752358.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    δ Ca2+/Calmodulin-Dependent Protein Kinase IIIsozyme-Specific Induction of Neurite Outgrowth in P19 Embryonal Carcinoma Cells (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Ca2+/calmodulin-dependent protein kinase II(CaMK-II) has been linked to the induction of differentiation in preneuronalcells. In these cells, δ isozymes represent the majority of CaMK-IIsexpressed and are activated by differentiation stimuli. To determine whetherδ CaMK-IIs are causative or coincident with in vitro differentiation, weoverexpressed wild-type, constitutively active, and C-terminal domains ofδ and γ CaMK-II isozymes in mouse P19 and NIH/3T3 cells usinghigh-efficiency transfections. At 1-2 days after transfection, onlyconstitutively active δ CaMK-II isozymes induced branched cellularextensions in both cell types. In P19 cells, retinoic acid induced neuriteextensions after 3-4 days; these extensions were coincident with a fourfoldincrease in endogenous CaMK-II activity. Extensions induced by both retinoicacid and δ CaMK-IIs contained class III β-tubulin in adiscontinuous or beaded pattern. C-terminal CaMK-II constructs disrupted theability of endogenous CaMK-II to autophosphorylate and blocked retinoicacid-induced differentiation. δ CaMK-II was found along extensions,whereas γ CaMK-II exhibited a more diffuse, cytosolic localization.These data not only support an extranuclear role for CaMK-II in promotingneurite outgrowth, but also demonstrate CaMK-II isozyme specificity in theseearly steps of neuronal differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0752380.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Analysis of Three Ptx2 Splice Variants on Transcriptional Activity and Differential Expression Pattern in the Brain (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Three different transcripts of the homeodomain gene termed pituitary homeobox (Ptx) 2 (Pitx2/Brx/Rieg/Solurshin/Arp) were cloned from different species encoding proteins belonging to the paired-like family of homeodomain proteins. Ptx2a (324 amino acids), Ptx2b (271 amino acids), and Ptx2c (318 amino acids) share the C terminus, including the homeodomain, and have different N termini. Here we report the comparative analysis of all three different Ptx2 splice variants for their transcriptional activity and their expression pattern in the adult rat brain. Ptx2 is able to trans-activate via different model promoters in different cell lines. A mild difference in trans-activating potential is observed among the splice variants, but the underlying mechanism is at present unknown. It is surprising that all Ptx2 transcripts displayed an identical expression pattern in the brain. This markedly restricted pattern is limited to the following brain areas: the anterior and intermediate lobes of the pituitary gland, the subthalamic nucleus, the posterior hypothalamic nucleus, the mammillary bodies, the red nucleus, and the deep gray layer of the superior colliculus. The data presented suggest that all variants of Ptx2 are involved in the development and regulation of distinct neuronal cell groups and the pituitary gland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751818.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Induction of Adrenomedullin During Hypoxia in Cultured Human Glioblastoma Cells (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Adrenomedullin is a potent vasodilator peptide originally isolated from pheochromocytoma. Adrenomedullin is produced by various types of cells including neurons and astrocytes. To explore possible pathophysiological roles of adrenomedullin in hypoxic brain, we studied the effects of hypoxia on the expression of adrenomedullin in T98G human glioblastoma cells by radioimmunoassay and northern blot analysis. Expression levels of adrenomedullin mRNA and immunoreactive adrenomedullin levels in the culture medium were increased by hypoxia about six- and about threefold, respectively. Treatment with cobalt chloride increased expression levels of adrenomedullin mRNA about threefold and immunoreactive adrenomedullin levels in the culture medium about threefold in T98G cells. Using actinomycin D, we showed that hypoxia did not cause the stabilization of the adrenomedullin mRNA, suggesting that the increased adrenomedullin mRNA levels in response to hypoxia are caused mainly by increased transcription. Treatment with cycloheximide caused increases in adrenomedullin mRNA levels in both normoxic and hypoxic states, raising the possibility that some protein(s) may act as a suppressor of adrenomedullin gene expression in T98G cells. These findings indicate that adrenomedullin is highly induced during hypoxia in T98G glioblastoma cells and suggest that increased expression of adrenomedullin during hypoxia may be important in the defense against hypoxia or ischemia in the brain.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751826.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Messenger RNAs Located in Myelin Sheath Assembly Sites (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The targeting of mRNAs to specific subcellular locations is believed to facilitate the rapid and selective incorporation of their protein products into complexes that may include membrane organelles. In oligodendrocytes, mRNAs that encode myelin basic protein (MBP) and select myelin-associated oligodendrocytic basic proteins (MOBPs) locate in myelin sheath assembly sites (MSAS). To identify additional mRNAs located in MSAS, we used a combination of subcellular fractionation and suppression subtractive hybridization. More than 50% of the 1,080 cDNAs that were analyzed were derived from MBP or MOBP mRNAs, confirming that the method selected mRNAs enriched in MSAS. Of 90 other cDNAs identified, most represent one or more mRNAs enriched in rat brain myelin. Five cDNAs, which encode known proteins, were characterized for mRNA size(s), enrichment in myelin, and tissue and developmental expression patterns. Two of these, peptidylarginine deiminase and ferritin heavy chain, have recognized roles in myelination. The corresponding mRNAs were of different sizes than the previously identified mRNA, and they had tissue and development expression patterns that were indistinguishable from those of MBP mRNA. Three other cDNAs recognize mRNAs whose proteins (SH3p13, KIF1A, and dynein light intermediate chain) are involved in membrane biogenesis. Although enriched in myelin, the tissue and developmental distribution patterns of these mRNAs differed from those of MBP mRNA. Six other cDNAs, which did not share significant sequence homology to known mRNAs, were also examined. The corresponding mRNAs were highly enriched in myelin, and four had tissue and developmental distribution patterns indistinguishable from those of MBP mRNA. These studies demonstrate that MSAS contain a diverse population of mRNAs, whose locally synthesized proteins are placed to contribute to myelin sheath assembly and maintenance. Characterization of these mRNAs and proteins will help provide a comprehensive picture of myelin sheath assembly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751834.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Intracellular pH on Translocation of Protein Kinase C Isozymes in Rat Pinealocytes (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: In rat pinealocytes, cytoplasmic alkalization causes protein kinase C (PKC) translocation, but the isozyme involved is not known. In this study, we investigated the effect of cytoplasmic alkalization on membrane-associated PKCα, δ, ε, and ζ, four isozymes present in the rat pineal gland. Treatment with NH4Cl, which had no effect on PKCζ, caused a sustained increase in membrane-associated PKCα, δ, and ε that lasted for at least 60 min. The effect of NH4Cl on PKCα, δ, and ε was reduced by sodium propionate, an agent that counteracts the effect of NH4Cl on intracellular pH. Both sodium propionate and 5-(N,N-hexamethylene)amiloride (HMA), two treatments that abolished the effect of norepinephrine on cytoplasmic alkalization, also reduced norepinephrine-mediated increases in membrane-associated PKCα, δ, and ε. In contrast, these two treatments did not have an effect on the increase in membrane-associated PKC isozymes caused by 4β-phorbol 12-myristate 13-acetate (PMA), an active phorbol ester, even though HMA was effective in abolishing PMA-mediated increases in intracellular pH. These results, apart from demonstrating that cytoplasmic alkalization by itself can cause translocation of PKCα, δ, and ε in rat pinealocytes, also indicate that the norepinephrine-stimulated cytoplasmic alkalization plays an important role in transducing signals from the adrenergic receptor to selective PKC isozymes. However, PKC translocation stimulated directly by PMA does not appear to be sensitive to changes in intracellular pH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751845.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Degradation of the Type I Inositol 1,4,5-Trisphosphate Receptor by Caspase-3 in SH-SY5Y Neuroblastoma Cells Undergoing Apoptosis (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The type I inositol 1,4,5-trisphosphate (IP3) receptor is selectively down-regulated in several neurodegenerative diseases, including Alzheimer's disease, Huntington's chorea, and ischemia, all conditions in which apoptotic neuronal loss occurs. In the present study, we used a neuronal cell line, human neuroblastoma SH-SY5Y cells, to investigate whether the levels of IP3 receptor are changed during apoptosis in these cells. Following induction of apoptosis by staurosporine, the immunoreactivity of the type I IP3 receptor in microsome preparations from SH-SY5Y cells was reduced within 2 h, with a further reduction during subsequent hours. Immunoblot analyses, using antibodies to poly(ADP-ribose) polymerase and spectrin breakdown products, revealed proteolysis of these caspase-3 substrates within 3 h, confirming that IP3 receptor cleavage is an early consequence of apoptosis. In vitro incubation of SH-SY5Y microsomes or immunopurified IP3 receptor from rat cerebellum with recombinant caspase-3 led to generation of immunoreactive breakdown products similar to those observed in intact cells, suggesting that the type I IP3 receptor is a potential substrate for caspase-3. Preincubation of the neuroblastoma cells with the caspase-3 inhibitor Z-Asp-Glu-Val-Asp-fluoromethyl ketone prevented IP3 receptor degradation. These results show that the type I IP3 receptor is a substrate for caspase-3 in neuronal cells and indicate that apoptotic down-regulation of IP3 receptor levels may contribute to the pathology of neurodegenerative conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751852.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    Nerve Tissue-Specific (GLUD2) and Housekeeping (GLUD1) Human Glutamate Dehydrogenases Are Regulated by Distinct Allosteric Mechanisms (2000)
    Oxford UK : Blackwell Science Ltd.
    Journal of neurochemistry 75 (2000), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Human glutamate dehydrogenase (GDH), an enzyme central to the metabolism of glutamate, is known to exist in housekeeping and nerve tissue-specific isoforms encoded by the GLUD1 and GLUD2 genes, respectively. As there is evidence that GDH function in vivo is regulated, and that regulatory mutations of human GDH are associated with metabolic abnormalities, we sought here to characterize further the functional properties of the two human isoenzymes. Each was obtained in recombinant form by expressing the corresponding cDNAs in Sf9 cells and studied with respect to its regulation by endogenous allosteric effectors, such as purine nucleotides and branched chain amino acids. Results showed that L-leucine, at 1.0 mM, enhanced the activity of the nerve tissue-specific (GLUD2-derived) enzyme by ∼1,600% and that of the GLUD1-derived GDH by ∼75%. Concentrations of L-leucine similar to those present in human tissues (∼0.1 mM) had little effect on either isoenzyme. However, the presence of ADP (10-50 μM) sensitized the two isoenzymes to L-leucine, permitting substantial enzyme activation at physiologically relevant concentrations of this amino acid. Nonactivated GLUD1 GDH was markedly inhibited by GTP (IC50 = 0.20 μM), whereas nonactivated GLUD2 GDH was totally insensitive to this compound (IC50 〉 5,000 μM). In contrast, GLUD2 GDH activated by ADP and/or L-leucine was amenable to this inhibition, although at substantially higher GTP concentrations than the GLUD1 enzyme. ADP and L-leucine, acting synergistically, modified the cooperativity curves of the two isoenzymes. Kinetic studies revealed significant differences in the Km values obtained for α-ketoglutarate and glutamate for the GLUD1- and the GLUD2-derived GDH, with the allosteric activators differentially altering these values. Hence, the activity of the two human GDH is regulated by distinct allosteric mechanisms, and these findings may have implications for the biologic functions of these isoenzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.2000.0751862.x
    Location Call Number Limitation Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...