bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tau protein induces bundling of microtubules in vitro: Comparison of different tau isoforms and a tau protein fragment
Authors: Scott C. W. , Klika A. B. , Lo M. M. S. , Norris T. E. , Caputo C. B. 
Published: January 2005

AbstractExpression of tau protein in non‐neuronal cells can result in a redistribution of the microtubule cytoskeleton into thick bundles of tau‐containing microtubules (Lewis et al.: Nature 342:498–505, 1989; Kanai et al.: J Cell Biol 109:1173–1184, 1989). We reconstituted microtubule bundles using purified tubulin and tau in order to study the assembly of these structures. Taxol‐stabilized tubulin polymers were incubated with various concentrations of recombinant human tau and examined by electron microscopy. With increasing concentrations of τ3 (tau isoform containing three microtubule binding domains) or τ4 (isoform containing four microtubule binding domains) the microtubules changed orientation from a random distribution to loosely and tightly packed parallel arrays and then to thick cables. In contrast, τ4L, the tau isoform containing four microtubule binding domains plus a 58‐amino acid insert near the N‐terminus, showed minimal bundling activity. τ4‐induced bundling could be inhibited by the addition of 0.5M NaCl or 0.4 mM estramustine phosphate, conditions which are known to inhibit tau binding to microtubules. A tau construct that contained only the microtubule binding domains plus 19 amino acids to the C‐terminus was fully capable of bundling microtubules. Phosphorylation of τ3 with cAMP‐dependent protein kinase had no effect on its ability to induce microtubule bundling. These results indicate that tau protein is directly capable of bundling microtubules in vitro, and suggests that different tau isoforms differ in their ability to bundle microtubule filaments. © 1992 Wiley‐Liss, Inc.
Antibody to beta‐amyloid precursor protein recognizes an intermediate filament‐associated protein in alzheimer's and control fibroblasts
Authors: Dooley N. P. , Gauthier S. , Durham H. D. 
Published: January 2005

AbstractThe expression of beta‐amyloid precursor protein (BAPP) and its mRNAs was studied in fibroblasts obtained from patients afflicted with Alzheimer's disease (AD) and age‐matched controls. Using reverse transcriptase‐polymerase chain reaction (RT‐PCR), transcripts corresponding to 770, 751, 714, and 695 amino acids were detected in both AD and control fibroblasts. Antibody 22C11 against BAPP (Boehringer Mannheim) labeled an intracellular protein, specifically localized to the intermediate filament network. In addition to bands of the predicted molecular weights for BAPP (120–135 kDa), Western blotting revealed a 57 kDa band which was not evident in samples of human brain. As cytoskeletal elements are vital in maintaining cellular architecture and various cell interactions, localization of BAPP or a related molecule to the cytoskeleton suggests a possible structural role for this protein within the cell. © 1992 Wiley‐Liss, Inc.
Nerve growth factor (NGF) receptors in a central nervous system glial cell line: Upregulation by NGF and brain‐derived neurotrophic factor
Authors: Spoerri P. E. , Romanello S. , Petrelli L. , Negro A. , Dal Toso R. , Leon A. , Skaper S. D. 
Published: January 2005

AbstractThe neurotrophic proteins nerve growth factor (NGF) and brain‐derived neurotrophic factor (BDNF) are related in their primary amino acid structures. In this study we investigated the extent to which the low‐affinity NGF receptor (LNGFR) in C6 glioma cells can discriminate between the neurotrophins NGF and BDNF. LNGFR‐immunoreactivity (IR) was studied in C6 cells treated for 16 hr with NGF (50 ng/ml) or BDNF (10 ng/ml), using immunogold labeling and electron microscopic morphometric analysis. The cells were exposed to the anti‐NGFR antibody 192‐IgG, followed by immunoglobulin conjugated with colloidal gold. Untreated C6 cells exhibited some surface gold label (positive LNGFR‐IR). Cells treated with NGF or BDNF displayed significantly increased LNGFR‐IR on all surfaces in terms of gold labeling, which was more pronounced in NGF‐treated cells. LNGFR‐IR was also localized in coated endocytotic vesicles, in smooth endoplasmic reticulum, and in secondary multivesicular lysosomes in neurotrophin‐treated and untreated cells. The increase in LNGFR protein was further substantiated by a correspondingly higher content of LNGFR mRNA detected after 15 hr of either NGF or BDNF treatment. These results suggest that the LNGFR in glial cells can be upregulated by the structurally related neurotrophins NGF and BDNF. © 1992 Wiley‐Liss, Inc.
Changes in chromatin proteins during optic nerve regeneration in the goldfish
Authors: Gossels J. M. , Lewis S. E. , Perrone‐Bizzozero N. I. , Benowitz L. I. 
Published: January 2005

AbstractRegeneration of the goldfish optic nerve involves massive changes in the structure and pattern of macromolecular synthesis in the retinal ganglion cells. To explore the mechanisms that underlie these events, we investigated the changes in chromatin proteins during the course of regeneration. Three major retinal chromatin proteins, two with apparent molecular weights of 58 kDa (C1 and C2) and one at 51 kDa (C3), all having isoelectric points around 5.5, showed a fourfold increase in their synthesis and/or accumulation by 14 days of regeneration. Synthesis of C1 and C3 decreased by day 32, the time at which the axons have grown back to the optic tectum and have formed many of their synapses; synthesis of C2 remained high through day 32. All three proteins bound to DNA‐cellulose and required high salt concentrations (0.2–0.5 M KCl) to be eluted. C1 and C2 had similar proteolytic digestion patterns and reacted with monoclonal antibodies that recognize the goldfish intermediate filament proteins of the ON complex. The proteins identified here could be involved in structural alterations in the chromatin, or might serve as transcription factors to regulate gene expression during nerve regeneration. © 1992 Wiley‐Liss, Inc.
Neuronal migration in cerebellar microcultures is inhibited by antibodies against a neurite outgrowth domain of laminin
Authors: Liesi P. , Seppälä I. , Trenkner E. 
Published: January 2005

AbstractThe functional role of laminin in neuronal migration was investigated by using polyclonal antibodies or their divalent (Fab′)2 fragments to a neurite outgrowth promoting domain of the B2 chain of laminin in a cerebellar microculture system widely recognized as a model for neuronal migration. We show here that these antibodies or their (Fab′)2 fragments totally inhibit migration of the mouse cerebellar granule cells along the glial and other neuronal cell processes. Antibodies to native laminin or other control antibodies have no inhibitory effect. Immunocytochemical analysis of the cerebellar microcultures indicates that the functional role of these antibodies may relate to the fact that the punctate deposits of laminin and its neurite outgrowth promoting domain accumulate in between the migrating neurons and the glial cells. These data provide the first direct evidence for the functional role of laminin and its neurite outgrowth domain in neuronal migration in the mammals. They further suggest that a neuronal cell surface contact with the extracellular deposits of a neurite outgrowth domain of the B2 chain of laminin may mediate neuronal‐glial interactions. © 1992 Wiley‐Liss, Inc.
Developmental expression of major myelin protein genes in the CNS of X‐Linked hypomyelinating mutant rumpshaker
Authors: Mitchell L. S. , Gillespie S. C. , McAllister F. , Fanarraga M. L. , Kirkham D. , Kelly B. , Brophy P. J. , Griffiths I. R. , Montague P. , Kennedy P. G. E. 
Published: January 2005

AbstractRumpshaker (rsh) is an X‐linked mutation causing hypomyelination of the CNS of mice and has recently been identified as an allele of jimpy (jp). The mutation (known as jprsh) differs in several respects from other X‐linked myelin mutants, including jp, in that mice have normal longevity, oligodendrocyte numbers are not decreased, and cell death is not a feature. Myelin sheaths are deficient in immunostainable PLP protein. The present study examines the developmental expression of the major myelin protein genes and translatability of PLP and MBP mRNA. Differences between the spinal cord and brain of mutants are evident in that mRNA levels are more markedly decreased in the brain. Protein levels are severely reduced in both locations and to a proportionately greater extent than the mRNA, particularly in the spinal cord where PLP RNA and protein are approximately 80% and 10–20%, respectively, of age‐matched wild type mice. DM‐20 protein, the other major product of the PLP gene, is disproportionately expressed in rumpshaker as is a 10 kDa proteolipid. In vitro translation studies indicate a marked decrease in PLP translation products from mutant RNA. There is no deficiency in the numbers of PLP mRNA‐expressing oligodendrocytes although the abundance per cell is reduced. The data suggest that the phenotypic effects of the mutation may be associated with reduced translation of major myelin proteins, in particular PLP and its incorporation into compact myelin. However, the mutation is compatible with survival of oligodendrocytes and their differentiation to the stage of expressing PLP/DM‐20 mRNA. © Wiley‐Liss, Inc.
Recombinant human ciliary neurotrophic factor alters the threshold of hippocampal pyramidal neuron sensitivity to excitotoxin damage: Synergistic effects of monosialogangliosides
Authors: Skaper S. D. , Negro A. , Dal Toso R. , Facci L. 
Published: January 2005

AbstractCiliary neurotrophic factor (CNTF) is a multifunctional protein which not only promotes neuronal survival in vitro and in vivo but also controls cell division of neuronal precursors, transmitter differentiation, and glial cell differentiation. Recent studies have indicated that neurotrophic factors can alter hippocampal neuronal threshold to excitotoxin sensitivity. To examine such a role for CNTF, cultures of rat embryonic hippocampal neurons were maintained with recombinant human CNTF for different times, prior to exposure to a toxic dose of glutamate at 5 days in vitro for a further 24 hr. The cytotoxic action of 200 μM glutamate (approximately 40% of pyramidal neurons remaining after 24 hr) was reduced in a concentration‐dependent manner in cultures receiving a prior exposure to CNTF within the first 3 days of cell plating: 30 ng/ml CNTF permitted about 75% of the initial number of pyramidal neurons to survive. Presentation of CNTF less than 48 hr before glutamate challenge was ineffective at up to 100 ng/ml. When pyramidal neurons were cultured with a subthreshold concentration (2 ng/ml) of CNTF together with 10 μM of the monosialoganglioside GM1 (or its inner ester form) in the same paradigm, the resulting neuronal survival was similar to that seen with 30 ng/ml CNTF in the face of a glutamate challenge. Such low doses of either CNTF or ganglioside alone were ineffective. The ability of trophic factors to influence the threshold of neuronal sensitivity to excitatory amino acid injury suggests that these proteins could play an important role in the reparative capacity of acutely traumatized central neurons and in neurodegenerative diseases linked to an excitotoxic mechanism. Furthermore, monosialogangliosides may represent useful pharmacological agents for facilitating neurotrophic factor‐initiated nerve cell recovery processes. © Wiley‐Liss, Inc.
Stereoselective effects of AMOA on non‐NMDA receptors expressed in Xenopus Oocytes
Authors: Wahl P. , Nielsen B. , Krogsgaard‐Larsen P. , Hansen J. J. , Schousboe A. , Miledi R. 
Published: January 2005

AbstractPharmacological characterization of the action of the novel non‐N‐methyl‐D‐aspartate non‐NMDA) antagonist AMOA (2‐amino‐3‐[3‐ (carboxymethoxy)‐5‐methylisoxazol‐4‐yl]propionate on glutamate receptors was investigated in Xenopus ooccytes injected with mouse brain mRNA. AMOA (150 μM) produced a nearly parallel shift to the right of the dose‐response curve for kainate‐induced currents. AMOA was found to have two different effects on AMPA receptors: (1) currents elicited by low concentrations of AMPA (6 μM) were inhibited by AMOA with an IC50 value of 160 ± 19 μM and (2) currents elicited by high concentrations of AMPA (100 μM) were potentiated with an IC50 value of 88 ± 22 μM. The maximal potentiating effect of AMOA on AMPA currents was around 170%. Furthermore, the two opposing effects of AMOA on AMPA responses are specific for the L‐configuration of AMOA. This unusual antagonistic/agonistic property of AMOA may explain its unusual properties with regard to antagonism of non‐NMDA receptor‐mediated events previously described.
Opposing influences of protein kinase activities on neurite outgrowth in human neuroblastoma cells: Initiation by kinase A and restriction by kinase C
Authors: Shea T. B. , Beermann M. L. , Leli U. , Nixon R. A. 
Published: January 2005

AbstractThe respective roles of cAMP‐dependent protein kinase (protein kinase A [PKA]) and protein kinase C (PKC) in the early stages of neurite outgrowth were examined in SH‐SY‐5Y human neuroblastoma cells. Forskolin or dbcAMP, agents that increase intracellular cAMP levels, and intracellular delivery of PKA catalytic subunit induced neurite outgrowth. The PKA inhibitor, N‐(2‐guanidinoethyl)‐5‐isoquinolinesulfonamide (HA 1004), prevented the increases, and decreased further the percentage of cells possessing short, filopodia‐like neurites in the absence of inducers. In contrast to effects on PKA activation, PKC activation by 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) reduced the percentage of filopodia‐like neurites elaborated by otherwise untreated cells, and prevented neurite outgrowth induced by PKA activators. PKC inhibitors 1‐(5‐isoquinolinesulfonyl)‐2‐methylpiperazine dihydrochloride (H7), staurosporine, and sphingosine induced neurite outgrowth.Neurites induced by PKA activation contained higher levels of tubulin immunoreactivity than those induced by PKC inhibition. Furthermore, PKA‐induced neurites rapidly retracted in the presence of colchicine, while those elaborated following PKC inhibition were more resistant. These data suggest that neurites elaborated in response to PKA activation are dependent upon microtubule polymerization, and that neurite induction following PKC inhibition is mediated by a different mechanism.PKA activators and PKC inhibitors exerted additive effects on neurite outgrowth, suggesting that the distinct pathways regulated by these two kinases function cooperatively during neuritogenesis. © Wiley‐Liss, Inc.
Anomalous phosphorylated neurofilament aggregations in central and peripheral axons of hens treated with tri‐Ortho‐cresyl phosphate (TOCP)
Authors: Jensen K. F. , Lapadula D. M. , Knoth Anderson J. , Haykal‐Coates N. , Abou‐Donia M. B. 
Published: January 2005

AbstractPrevious biochemical studies demonstrated a dramatic increase in phosphorylation of cytoskeletal proteins that occurs early in organophosphorus ester‐induced delayed neurotoxicity (OPIDN). In this report we present immunohistochemical evidence that there is anomalous aggregation of phosphorylated neurofilaments within central and peripheral axons following organophosphate exposure. The morphology, location, and time of appearance of these aggregations are consistent with the hypothesis that the aberrant phosphorylation of cytoskeletal elements is an antecedent to the focal axonal swelling and degeneration characteristic of OPIDN. © Wiley‐Liss, Inc.
Autoradiographic analysis of second messenger and neurotransmitter receptor bindings in the strionigral system of the postischemic rat brain
Authors: Nagasawa H. , Araki T. , Kogure K. 
Published: January 2005

AbstractWe studied the postischemic alterations of second messenger and receptor systems focusing on the striobigral pathway in order to clarify the mechanism of the delayed neuronal changes in remote areas of the rat brain after transient focal ischemia. Chronological changes of [3H]forskolin and [3H]SCH 23390 binding sites and 45Ca accumulation were determined by using autoradiographic methods after 90 min of right middle cerebral artery (MCA) occlusion and after such occlusion followed by differnt periods of recirculation. After the ischemic insult, 45Ca accumulation extended to the lateral segment of the caudate putamen (CPu‐L) and to the cerebral cortex, both supplied by the occluded MCA. After the ischemia, [3H]forskolin binding sites were found to be markedly decreased in the early stage in the CPu‐L, the ischemic focus in this model, but reduction of the dopamine D‐1 receptor sites was first detected there 1 day after the ischemia. On the contrary, in the exo‐focal remote areas, there was no alteration of either [3H]forskolin of D‐1 receptor binding sites on day 1. However, 3 days after the ischemia, marked reduction of both these binding sites was first observed in the ipsilateral substantia nigra, which had not been directly affected by the original ischemic insult. These postischemic delayed phenomena observed in the substantia nigra developed concurrently with abnormal 45Ca accumulation. These results suggest that strionigral terminal degeneration in the substantia nigra is caused by precedent ischemic damage of the ipsilateral caudate putamen and that intracellular signal transduction including both second messenger and receptor systems may be involved prior to the neuronal damage in the exo‐focal postischemic brain areas. © 1992 Wiley‐Liss, Inc.
Ethanol administration during early embryogenesis affects neuronal phenotypes at a time when neuroblasts are pluripotential
Authors: Kentroti S. , Vernadakis A. 
Published: January 2005

AbstractOur previous studies have reported that ethanol administration during a critical period of development profoundly affects the expression of neuronal phenotypes in whole brains of chick embryos. The present study examines (a) the long‐lasting effects on anatomically discrete regions of the developing chick CNS. Ethanol (10 mg/50 μl) was administered to embryos via the air sac from E1 to E3. Embryos were sacrificed on days 4, 8, 10, or 15 of embryonic development (E4, E8, E10, E15) and assayed in specific regions of the CNS for glutamate decarboxylase (GAD) or choline acetyltransferase (ChAT) as markers for GABAergic or cholinergic neurons, respectively. The magnitude of the developmental profile for ChAT was highest in spinal cord (SC), with similar profiles observed for cerebral hemispheres (CH) and optic lobes (OL). In contrast, the developmental profile for GAD was highest in OL and lowest in SC. Thus, neuronal phenotypes inhabit specific CNS areas from early primordial stages of development. Furthermore, cholinergic neuronal populations in discrete CNS areas reached mature levels by E10, whereas GABAergic populations continued to increase throughout the experimental period. We suggest that GABAergic precursor neuoblasts may differentiate at a later embryonic age and that specific regional factors may play a role in neuronal distribution and the rate of maturation. As reported previously, primordial CNS areas exposed to ethanol (E1‐E3) exhibited a differential sensitivity. Cholinergic neuronal expression in CH remained retarded throughout the experimental period examined, whereas the early decline observed at E4 in SC cholinergic expression was reversed by E15. In contrast, the enhanced GABAergic expression exhibited at E4 continued up to E15. This differential neuronal sensitivity to ethanol is interpreted to indicate that (a) ethanol may shift neuronal fates during early neuronal commitment and (b) regional factors may play an important role for neuronal recovery following ethanol insult. © 1992 Wiley‐Liss, Inc.
Molecular analysis of the nerve growth factor inducible ornithine decarboxylase gene in PC12 cells
Authors: Muller S. R. , Huff S. Y. , Goode B. L. , Marschall L. , Chang J. , Feinstein Stuart C. 
Published: January 2005

AbstractIn an effort to understand molecular mechanisms by which nerve growth factor (NGF) regulates gene expression, we have isolated a full‐length rat cDNA clone encoding ornithine decarboxylase (ODC) and utilized this probe to identify and examine the transcriptionally active, NGF inducible ODC gene in rat PC12 cells. This same gene is also responsive to epidermal growth factor, basic fibroblast growth factor, and dibutyryl cAMP. Primer extension analysis demonstrates that both basal and NGF induced transcription of the ODC gene utilize the same major transcriptional start site, demonstrating that NGF acts to increase transcriptional activity at the basal start site as opposed to unmasking an alternative, stronger start site. Functional promoter analysis reveals the presence of a constitutive core promoter residing between positions −201 and +390, relative to the start site of transcription. Additional analyses reveal that sequences in the region −7800 to +2257 are insufficient to mediate NGF induced transcriptional activation, demonstrating that at least some of the regulatory sequences necessary for NGF mediated transcriptional induction of the ODC gene must reside at relatively enormous distances from the transcriptional start site. Such a long distance transcriptional regulatory mechanism is unique when compared with other NGF responsive genes that have been similarly analyzed. © 1993 Wiley‐Liss, Inc.
Establishment of an astrocyte progenitor cell line: Induction of glial fibrillary acidic protein and fibronectin by transforming growth factor‐β1
Authors: Yoshida T. , Takeuchi M. 
Published: January 2005

AbstractAn immortalized clonal cell line (AP‐16) has been established from glial cultures obtained from neonatal mouse cerebra by multipassages under serum‐free conditions. Immunofluorescent experiments showed that AP‐16 cells expressed a marker for glial progenitors (A2B5) and did not express markers for oligodendrocytes (galactocerebroside) or mature astrocytes (glial fibrillary acidic protein: GFAP). Treatment with transforming growth factor‐β1 (TGF‐β1) or fetal calf serum (FCS) for 2 days induced AP‐16 cells to differentiate into A2B5‐negative, GFAP‐positive, phenotypically mature astrocytes. AP‐16 cells depended on epidermal growth factor for survival, and their growth was inhibited by FCS. These results indicate that AP‐16 cells retained the properties of astrocyte progenitors. An enzyme‐linked immunosorbent assay showed that AP‐16 cells synthesized fibronectin and laminin, and that the expression of fibronectin was increased by TGF‐β1. AP‐16 cells should be useful for studying the roles of TGF‐β1 in the differentiation of astrocyte progenitors. © 1993 Wiley‐Liss, Inc.