bluuebunny/crossref_metadata_2025_split huggingface dataset:
Differential regulation of the nerve growth factor and brain‐derived neurotrophic factor genes in L929 mouse fibroblasts
Authors: D'Mello S. R. , Jiang C. , Lamberti C. , Martin S. C. , Heinrich G. 
Published: January 2005

AbstractNerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF) are structurally related survival and differentiation factors for distinct sets of peripheral and central neurons. The regulation of NGF gene expression has been extensively studied in L929 mouse fibroblasts. L929 cells also express the BDNF gene. Northern blot hybridization analysis revealed 4 discrete BDNF mRNA species in L929 cells and rat hippocampus after induction of seizures with kainic acid. Serum as well as 12‐O‐tetradecanoyl phorbol‐13‐acetate (TPA) stimulated NGF and all 4 BDNF mRNAs in L929 cells. Treatment with both agents induced NGF mRNA to a much larger extent than the BDNF mRNAs. The induction of the BDNF mRNAs was rapid, with nearly maximal levels by 1 hr. In contrast, NGF mRNA induction occurred later and peaked at 4–6 hr. Both NGF and BDNF mRNA induction were inhibited by actinomycin D. Cycloheximide, on the other hand, inhibited only NGF but not BDNF mRNA induction. Corticosterone rapidly decreased NGF mRNA but not the BDNF mRNAs, and had no effect on seizure‐induced NGF or BDNF mRNAs. Forskolin did not stimulate NGF or BDNF mRNAs. In contrast to NGF mRNA, forskolin did not interfere with the serum induction of BDNF mRNAs. These results demonstrate that 2 genes which encode closely related neurotrophic factors are differentially regulated in L929 cells. The molecular mechanisms which bring about this differential regulation remain to be elucidated. © 1992 Wiley‐Liss, Inc.
Biphasic changes in NCAM level after an NMDA lesion to the hippocampal formation: A quantitative dot‐immunobinding assay
Authors: Wang S. , Lees G. J. , Bock E. , Hamberger A. , Haglid K. G. 
Published: January 2005

AbstractWith a quantitative dot‐immunobinding assay, the time course changes of neuronal cell adhesion molecule (NCAM) concentrations and total tissue content were monitored in the rat hippocampus after a 40 nmol NMDA injection. A biphasic alteration was observed; a decrease occurred at day 3, an increase at day 30. The time course of changes differed from that of the glial fibrillary acidic protein (GFAP), a marker for reactive astroglial cell, but was similar to that for the markers of sprouting neurites, i.e., low (L) and high (H) molecular weight subunits of the neurofilament polypeptides. It is suggested that NCAM is implicated in the onset of neurite sprouting in the hippocampus after an excitotoxic trauma. © 1992 Wiley‐Liss, Inc.
Age‐related changes in rat brain monoamines release: Peculiarity of dopamine release
Authors: Cerrito F. , Aloisi G. , Arminio P. 
Published: January 2005

AbstractOur aim has been to investigate the ability of the rat brain to retain its level of neurotransmitter release over life. We have investigated the neurotransmitter release from the rat brain synaptosomes prelabeled with 3H‐DA, 3H‐NA, or 3H‐5HT, and perfused with Krebs‐Ringer medium alone (basal release) or containing a high K+, calcium ionophore, tyramine or amphetamine (evoked release). Brain areas have been dissected of animals 45 days and 4, 6, and 11 months old. The results have shown a gradual reduction of the 3H‐NA release evoked by a high K+ from 45 days to 6 months, which is stabilized until 11 months of age. The reduction rate has been relatively different from the brain areas investigated (36% for the frontal cortex and 26% for the hippocampus and cerebellar cortex). A similar reduction has been seen with 3H‐5HT released from synaptosomes of the frontal cortex, hippocampus, and striatum. Surprisingly, the 3H‐DA release that was evoked by high K+ was greater in rats 11 months old than in younger rats; this effect has been seen in synaptosomes from the caudate and the frontal cortex. The calcium ionophore A23187 has shown a releasing picture similar to a high K+. When we analyzed a nonexocitotic, but probably carrier mediated, release (evoked by tyramine or amphetamine), there was reduced release of all of the above neurotransmitters from 45 days to 11 months of age. We presume that there have been adaptative changes in neurotransmitter evoked release due to changes in Ca++ utilization, as inferred from the results from calcium ionophore experiments and carrier performance. Aging seems to have preserved the extracellular neurotransmitter concentrations of Na and 5HT, compensating for the decreased carrier performance with a reduced depolarization rate of nerve terminals. DA homeostasis seems to have been altered with normal aging and may produce an elevation in extracellular DA and in its metabolite, yielding free radicals. This mechanism may play a role in degenerative changes associated with normal aging. © 1993 Wiley‐Liss, Inc.
Application of synthetic phospho‐ and unphospho‐ peptides to identify phosphorylation sites in a subregion of the tau molecule, which is modified in Alzheimer's disease
Authors: Liu W.‐K. , Moore W. T. , Williams R. T. , Hall F. L. , Yen Shu‐Hui 
Published: January 2005

AbstractPhospho‐ and unphospho‐ peptides were used to define the essential sequence for a tau epitope, which is recognized by Tau‐1 antibody and phosphorylated in Alzheimer's disease (AD). The epitope was mapped within the amino acid residues 192–199 of tau and was phosphorylated by the p34cdc2/p58cyclin A proline directed kinase (PDPK), but not by purified mitogen activated protein kinase (p42mapk). Addition of phosphate to the last serine of the epitope was the most effective in abolishing the reactivity of the epitope to Tau‐1 antibody. Our results suggest that one and possibly more members of the PDPK family may play a role in the pathogenesis of AD. © 1993 Wiley‐Liss, Inc.
Isolation and age‐related characterization of mouse Schwann cells from dorsal root ganglion explants in type I collagen gels
Authors: Chi H. , Horie H. , Hikawa N. , Takenaka T. 
Published: January 2005

AbstractA technique for isolation of adult Schwann cells (ScC) from dorsal root ganglia (DRG) is described. Decapsulated DRG explants embedded into type I collagen gels were cultured for 3 days in serum‐free medium during which ScC migrated from the explant. These explants were then grown in serum‐supplemented medium to allow ScC proliferation. On day 10 the number of ScC isolated from DRG explants per mouse was about 2.5 × 105, and the purity was greater than 95%. This culture system provided sufficient numbers of highly purified adult ScC in a shorter culture period (2–3 times) than other methods. We used ScC from this method to determine the age‐related changes in attachment, growth, and survival of ScC cultured in serum‐free medium. The attachment capacity of adult ScC on type I collagen or polylysine was similar to that of newborn ScC. However, the collagen promoted growth and survival of adult ScC but not that of neonatal ScC, indicating age‐related differences of ScC properties in vitro. © 1993 Wiley‐Liss, Inc.
Interleukin‐2 as a neurotrophic factor for supporting the survival of neurons cultured from various regions of fetal rat brain
Authors: Awatsuji H. , Furukawa Y. , Nakajima M. , Furukawa S. , Hayashi K. 
Published: January 2005

AbstractInterleukin(IL)‐2 supported the survival and enhanced neurite extension of cultured hippocampal neurons prepared from embryonic 18‐day‐old rats. This neurotrophic effect was observed at concentrations of 2 to 200 U/ml, and almost all the neurons could survive for more than 2 days in the presence of 200 U/ml of IL‐2. This viability‐promoting effect of IL‐2 on the neurons was completely blocked with anti‐IL‐2 antibodies. IL‐2 also supported the survival of cultured cortical, striatal, and septal neurons. These results indicate that IL‐2 has a survival‐promoting effect on a wide variety of neurons. On the other hand, IL‐2 did not affect the choline acetyltransferase (ChAT) activity of striatal neurons, suggesting that this cytokine does not act as a differentiation factor for striatal cholinergic neurons. © 1993 Wiley‐Liss, Inc.
Identification of a collagen potentiated neurite promoting factor isolated from C6 glioma cells
Authors: Coyle D. E. 
Published: January 2005

AbstractThe C6 glial cell line has been used as a model cell system for the investigation of new glial produced neurotrophic and neurotropic molecules. By using the C6 cell line grown in a defined medium on collagen, this laboratory has isolated a distinct neurite promoting factor (NPF) that is potentiated by the presence of collagen (CPNPF). We have observed that C6 cells cultured in a defined medium on collagen (rat type‐I) slowed their growth rate and expressed an astrocytic‐ or oligodendrocytic‐like morphology. CPNPF, at this state of purity, appears to be a distinct NPF which induces neurite outgrowth (neurites of 1 or more somal diameters) in PC12 cells. These neurite promotion effects, however, appear to support the neuron morphology for only a short period (4 days) of time without the presence of neurotrophic factor (NTF). The neurite promoting activity is ineffective in inducing neurite outgrowth using mouse neuroblastoma cells (neuro‐2a). CPNPF appears to be a heat stable protein whose activity does not depend on the presence of intact collagen, heparin sulfate proteoglycan (HSPG), or chondroitin sulfate proteoglycan (CSPG). Exposure to dissociative conditions results in a loss of neurite promoting activity. CPNPF is not a glycoprotein that contains an accessible α‐D‐mannopyranosyl, α‐D‐glucopyranosyl, or a sterically related residue (hydroxyl groups in the C‐3,4, and 5 positions). Although these residues are not present on all glycoproteins, it does indicate that CPNPF is most likely not a glycoprotein. CPNPF activity is not blocked by neutralizing antibodies directed toward NGF, β‐FGF, IL‐1β, IL‐6, TGF‐β2, TGF‐β1.2, TGF‐β3, TGF‐β5, or EGF. CPNPF appears to either be oligomeric protein or a complex of proteins. On the basis of indirect evidence, it does not appear to be glial derived protease nexin‐I. The alteration in morphology of the C6 glial cell line by serum‐free conditions in the presence of collagen may have induced the production of a potentially new NPF not seen by previous investigators. © 1993 Wiley‐Liss, Inc.
p44mpk MAP kinase induces aizheimer type alterations in tau function and in primary hippocampal neurons
Authors: Lu Q. , Soria J. P. , Wood J. G. 
Published: January 2005

AbstractAbnormally phosphorylated tau protein is a major component of the cytoskeletal pathology of Alzheimer's disease (AD) found in the neurofibrillary tangle (NFT) and neuritic plaque (NP). Identification of the kinase responsible for this phosphorylation has been difficult. In the test tube, several proline‐directed kinases, particularly mitogen‐activated protein (MAP) and cdc2 kinase, phosphorylate tau on sites that appear to mimic the abnormally phosphcrylated sites in AD. Important unanswered issues include: (1) whether this phosphorylation event occurs in the tightly regulated environment of a living cell; (2) whether this phosphorylation of tau affects its functional properties; and (3) what is the subcellular relationship of proline‐directed kinases and tau. We show here that tau can be phosphorylated in cultured hippocampal neurons by the MAP kinase p44mpk and phosphorylation of tau compromises its functional ability to assemble microtubules. We show further that MAP kinase copurifies with microtubule fractions where it is tyrosine phosphorylated and presumably active. These studies address and raise several important issues regarding the regulation of tau phosphorylation in normal and AD brain. © 1993 Wiley‐Liss, Inc.
Alkylcatechols regulate NGF gene expression in astroglial cells via both protein kinase C‐and cAMP‐independent mechanisms
Authors: Furukawa Y. , Furukawa S. , Omae F. , Awatsuji H. , Hayashi K. 
Published: January 2005

AbstractIt has been previously demonstrated that, in mouse astroglial cells and fibroblast cells in culture, alkylcatechols cause a rapid increase in the nerve growth factor (NGF) mRNA level followed by a marked increase in the amount of NGF released into the medium. To understand the mechanism of this alkylcatechol effect on NGF gene expression in astroglial cells, we examined the effects of protein kinases that influence intracellular signal transduction and of their inhibitors. The reagents to increase the intracellular content of cyclic AMP (cAMP) such as dibutyryl cyclic AMP (Bt2cAMP), forskolin, or cholera toxin did not mimic alkylcatechol induction of NGF gene expression. Phorbol ester, a direct activator of protein kinase C (PKC), caused an increase in the NGF synthesis/secretion. The stimulatory effect of homocatechol (4‐methylcatechol) on NGF synthesis was not completely inhibited by staurosporine, an inhibitor of PKC. The treatment of cells with homocatechol resulted in the translocation of PKC from cytosol to membrane‐associated fractions, although the levels of the subcellular location of PKC were not correlated with the level of the induction of NGF gene expression. The concomitant administration of homocatechol (10−4M) and PMA (10−8−10−6 M) evoked a drastic and prolonged increase in the NGF mRNA level, and also markedly increased the amounts of NGF secreted by the cells (approximately 150‐fold). This synergism was inhibited in part by staurosporine, but the level of increase in NGF mRNA and in NGF protein was rather greater than that of activation of PKC.These results suggest that neither PKC‐dependent pathway nor cAMP‐dependent pathway is dominant in the stimulatory effect of alkylcatechol on NGF synthesis. © 1993 Wiley‐Liss, Inc.
Transient requirement for vimentin in neuritogenesis: Intracellular delivery of anti‐vimentin antibodies and antisense oligonucleotides inhibit neurite initiation but not elongation of existing neurites in neuroblastoma
Authors: Shea T. B. , Beermann M. L. , Fischer I. 
Published: January 2005

AbstractVimentin is initially expressed by nearly all neuronal precursors in vivo, and is gradually replaced by neurofilaments shortly after the immature neurons become postmitotic (Cochard and Paulin, 1984, J Neurosci 4:2080; Tapscott et al., 1981, Dev Biol 86:40). A transient increase in neuritic vimentin filaments occurs within the first day of dbcAMP‐mediated neurite induction in NB2a/d1 neuroblastoma, after which vimentin levels rapidly decline and neurofilaments increase (Shea, 1990, Brain Res 521:343). In the present study, we tested the possibility that vimentin filaments may function in neurite elaboration by inducing neuritogenesis under conditions where vimentin expression and assembly was inhibited. Intracellular delivery of anti‐vimentin antiserum into transiently permeabilized NB2a/d1 cells prevented the initial elaboration of neurites, but did not retract existing neurites. By contrast, intracellular delivery of antiserum directed against the low molecular weight neurofilament subunit or normal rabbit antiserum did not affect neurite outgrowth. Treatment with vimentin antisense oligonucleotides reversibly depleted vimentin synthesis and steady‐state levels, and prevented neurite initiation, but did not induce retraction of existing neurites. These findings point toward an hitherto undetected role for vimentin in the initiation of neurite outgrowth. © 1993 Wiley‐Liss, Inc.
Proliferation and differentiation properties of bipotent glial progenitor cell lines immortalized with the adenovirus E1A gene
Authors: Galiana E. , Bernard R. , Borde I. , Rouget P. , Evrard C. 
Published: January 2005

AbstractBipotent glial progenitors have been immortalized by the transfer of the adenovirus E1A gene into primary cultured cells from embryonic rat brain. The lines obtained are phenotypically untransformed, retain growth contact‐inhibition, and are able to differentiate, unless they are surtransfected with transforming oncogenes. Depending on the growth conditions, these immortalized cells express differentially either oligodendrocyte or astrocyte‐specific markers and genes. After being seeded in serum‐free medium, they display gangliosides recognized by A2B5 monoclonal antibody, and then they express sequentially O4 epitopes, galactocerebroside, and the myelin protein DM20. When grown in serum‐supplemented medium, the cells express at first A2B5 epitopes, and then transiently O4 and galactocerebroside; after reaching confluence, O4 and galactocerebroside become undetectable, whereas the cells begin to coexpress glial fibrillary acidic protein and glutamine synthetase. These results indicate that the cell lines can undergo a differentiation reminiscent both of O‐2A progenitors and of plastic process‐bearing glial subpopulations. The cells were also genetically marked by the stable introduction of the nlslacZreporter gene. Thus, the lines could be useful for studying direct interactions in vitro, or for post‐grafting investigations. They should also provide a model for studying the mechanisms involved in the commitment and in the control of proliferation and differentiation of this cell lineage. This suggestion is consistent with the data indicating a growth arrest‐dependent differential expression of a novel gene encoding a protein with a helix‐loop‐helix domain. © 1993 Wiley‐Liss, Inc.
Phosphorylation and disruption of intermediate filament proteins in oligodendrocyte precursor cultures treated with calyculin A
Authors: Almazan G. , Afar D. E. H. , Bell J. C. 
Published: January 2005

AbstractTreatment of primary cultures of oligodendrocyte precursors with calyculin A, a potent inhibitor of protein phosphatases 1 and 2A, caused the phosphorylation of two intermediate filament components, nestin and vimentin. Phosphoamino acid analysis demonstrated that phosphorylation took place mainly on serine and to a lesser extent on threonine residues. In addition, calyculin A treatment caused a shift in the distribution of the two proteins from the Triton‐X‐100 insolube fraction to the detergent soluble fraction as demonstrated by immunoblotting. This redistribution, which was evident within 15 min after treatment and was nearly completed by 90 min, was accompanied by a disruption of the intermediate filament network. Thus, both nestin and vimentin retracted from the cytoplasmic processes to form a large perikaryal ring as shown by immunocytochemical analysis. Both morphological and biochemical changes were reversed 2–5 hr after removal of calyculin A from the culture medium. © 1993 Wiley‐Liss, Inc.
Nitric oxide synthase in cultured endothelial cells of cerebrovascular origin: Cytochemistry
Authors: Morin A. M. , Stanboli A. 
Published: January 2005

AbstractCultured cells derived from the cerebromicrovasculature can be shown to contain the enzyme nitric oxide synthase (NOS) by NADPH diaphorase staining. Nos is located largely as a distinct crescent adjacent to the nuclear membrane. NOS in these cells appears to be associated with the microtubule and microfilament structures and the Golgi apparatus of the cell as opposed to being freely soluble in the cytoplasm or bound to the plasma membrane. Disruption of the integrity of these structures with colchicine or cytochalasin B causes a change in the subcellular localization of NOS as well as a change in the intensity of staining. © 1993 Wiley‐Liss, Inc.This article is a US Government work and, as such, is in the public domain in the United States of America.
Expression of mRNA for neurotrophic factors and their receptors in the rat dorsal root ganglion and sciatic nerve following nerve injury
Authors: Sebert M. E. , Shooter E. M. 
Published: January 2005

AbstractThe adult rat dorsal root ganglion (DRG) produces mRNA for the neurotrophic factors nerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF) and contains large populations of neurons responsive to these factors. We report that following a focal crush injury of the sciatic nerve, NGF mRNA expression increases threefold and BDNF mRNA twofold, in the ipsilateral L4 and L5 DRGs. The mRNAs encoding the cognate neurotrophin receptors, p75NGFR, trkA, and trkB were expressed in the DRG throughout the post‐injury time course, suggesting that DRG neurons remain responsive to both NGF and BDNF. p75NGFR mRNA levels became transiently depressed in the DRG during the first several days after the lesion but returned to normal within 1 week. trkB mRNA was expressed in the normal sciatic nerve and levels were not altered by nerve crush. RNase protection assays detected both full‐length and truncated trkB transcripts in the DRG, but only truncated trkB mRNA, lacking the tyrosine kinase domain, was detected in the sciatic nerve. Likewise, trkA transcripts were not detected by RNase protection in normal sciatic nerve or in a segment of nerve distal to the crush site. These results are consistent with a model in which regenerating sensory neurons are supported by neurotrophic factors synthesized within the DRG. © 1993 Wiley‐Liss, Inc.
Glutamate neurotoxicity in mesencephalic dopaminergic neurons in culture
Authors: Kikuchi S. , Kim S. U. 
Published: January 2005

AbstractThe neurotoxic effect of glutamate in cultured mouse mesencephalic dopaminergic neurons was investigated. Neuron‐rich cell cultures were prepared from 13–14‐day‐old fetal mouse ventral mesencephalic tissue. Cultures were exposed to glutamate for 10 min and evaluated for glutamate neurotoxicity (GNT) 18–24 hr later by tyrosine hydroxylase (TH) immunostaining, microtubule associated protein‐2 (MAP2)immunostaining, and radiolabeled dopamine uptake assay.In glutamate‐exposed cultures, the number of TH‐positive neurons and the level of dopamine uptake were reduced to 40% (35–45%) and 50% (47–52%), respectively, of control cultures. The number of MAP2‐positive neurons was also reduced to 47%, indicating that the GNT was not restricted or selective to dopaminergic neurons.It is concluded that GNT was mediated by the N‐methyl‐D‐aspartic acid (NMDA) receptor from the following observations: (1) GNT was completely blocked by MK‐801, an NMDA receptor antagonist; (2) NMDA itself was as toxic as glutamate; (3) 6‐cyano‐7‐nitroquinoxaline‐2, 3‐dione (CNQX), an antagonist of the α‐amino‐3‐hydroxy‐5‐methylisoxazole‐4‐propionic acid/kainate (AMPA/KA) receptor, did not block GNT; (4) kainate did not show neurotoxicity at a low concentration; and 5) two modulators of the NMDA receptor, 7‐chlorokynurenic acid and magnesium, were effective in blocking GNT.Protective effects of phorbol myristate acetate, a tumor promoter, and gangliosides (GM1 and GT1b on GNT were also demonstrated. Possible interactions between GNT and several protein kinase cascades were also investigated. Forskolin, an activator of adenyl cyclase and protein kinase A, showed some protective effect on GNT. But okadaic acid, an inhibitor of phosphatases, and genistein, a tyrosine kinase inhibitor, did not show any protective effect.These results suggest that (1) glutamate is capable of causing neuronal death in the substantia nigra; (2) GNT on dopaminergic neurons is mainly mediated by the NMDA receptor under the conditions of our study; (3) protein kinase C translocation is a key mechanism of GNT; and (4) there is an interplay of a signal transduction system in the pathomechanism of GNT. © 1993 Wiley‐Liss, Inc.