bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclic AMP has a differentiative effect on an immortalized oligodendrocyte cell line
Authors: Jensen N. A. , Smith G. M. , Garvey J. S. , Shine H. D. , Hood L. 
Published: January 2005

AbstractWe investigated the effects of increasing the concentration of intracellular cyclic adenosine monophosphate (cAMP) on genes associated with oligodendrocyte differentiation in an immortalized glial cell line, 6E12, derived from the spinal cord of an MBP‐SV40 large T‐antigen transgenic mouse. Raising intracellular levels of cAMP induced expression of oligodendrocyte differentiation antigens recognized by O4 and anti‐galactocerebroside antibodies, up‐regulated expression of the proteolipid protein (PLP) gene, and down‐regulated glial fibrillary acidic protein (GFAP) expression. There was no treatment effect on myelinassociated glycoprotein (MAG) expression. These phenotypic changes are consistent with oligodendrocyte differentiation. Treatment of 6E12 cells with dibutyryl cyclic AMP (DBC) down‐regulated myelin basic protein (MBP) gene expression, perhaps, because it also up‐regulated expression of a putative MBP repressor SCIP/Tst‐1. Moreover, the 6E12 cells expressed high levels of MBP mRNA but no MBP translation products were detected in the presence or absence of DBC. This immortalized glial cell line is proposed as a CNS model for cAMP‐modulated myelin gene expression and for post‐transcriptional regulation of MBP. © 1993 Wiley‐Liss, Inc.
38‐Amino acid form of pituitary adenylate cyclase activating peptide induces process outgrowth in human neuroblastoma cells
Authors: Deutsch P. J. , Schadlow V. C. , Barzilai N. 
Published: January 2005

AbstractPermanent cell lines from human neuroblastoma, a sympathoadrenal malignancy, are known to exhibit a more neuronal phenotype characterized by outgrowth of long processes in response to multiple second messenger analogs. In this report we demonstrate that the 38‐amino acid form of a peptide homologous to vasoactive intestinal peptide (VIP), pituitary adenylate cyclase activating peptide (PACAP), as well as the 27‐amino acid form of PACAP, induce NB‐OK human neuroblastoma cells to extrude cellular processes within 5 hr of treatment with either peptide at 10−8 M. Treatment of NB‐OK cells with PACAP38 or PACAP27 at 10−8 M for 1 hr also elevates cAMP content greater than 100‐fold and inositol lipid turnover 11‐ to 12‐fold. VIP acutely induces process outgrowth and elevates intracellular second messenger levels in NB‐OK cells only at higher concentrations, 10−6 M or greater. In contrast to the equipotency of PACAP27 and PACAP38 in stimulating the outgrowth of processes observed after 5 hr of treatment, PACAP38 is much more potent than PACAP27 when NB‐OK cells are scored for process outgrowth after 72 hr of treatment. Correlating with the extended time course over which morphologic changes are seen with PACAP38, cAMP levels remain elevated for a more prolonged time span during treatment with PACAP38 than PACAP27. After 72 hr of treatment with PACAP38 versus treatment with PACAP27, cAMP levels are elevated 10‐fold versus 3‐fold, respectively. PACAP38 at 10−8 M also induces process outgrowth in two additional human neuroblastoma lines tested, SMS‐KAN and LA‐N‐1, whereas PACAP27 and VIP at the same concentration are less effective. The effects of PACAP38 on neuroblastoma cells may be a model for neurotrophic activities of PACAP38 via G protein‐linked intracellular messengers in human sympathoadrenal cells. © 1993 Wiley‐Liss, Inc.
Pentylenetetrazol seizures increase pro‐nerve growth factor‐like immunoreactivity in the reticular thalamic nucleus and nerve growth factor mRNA in the dentate gyrus
Authors: Humpel C. , Ebendal T. , Cao Y. , Olson L. 
Published: January 2005

AbstractNeurotrophins may have a neuroprotective role and are probably involved in the control of axonal sprouting and synaptic plasticity. An antibody raised against a pro‐sequence of nerve growth factor (NGF) was tested. In control undisturbed rats, a strong immunoreactivity was detected in scattered cells in and around the pyramidal and granule cell layer of the hippocampus and a moderate labeling was found in the reticular thalamic nucleus. In situ hybridization showed specific expression of NGF mRNA in a similar population of scattered cells in the hippocampal formation but not in the reticular thalamic nucleus. Acute epileptic seizures, induced by a convulsive dose of 50 mg/kg pentylenetetrazol (PTZ), strongly in creased NGF mRNA in neurons of the granular layer of the dentate gyrus 3 hr but not 6 hr after the injection. No change in pro‐NGF‐like immunoreactivity was observed in the hippocampus or reticular thalamic nucleus after acute seizures. Chemical kindling was induced by daily injections of subconvulsive doses (30 mg/kg) of PTZ for 4 weeks. This treatment significantly increased pro‐NGF‐like immunoreactivity in the reticular thalamic nucleus but did not affect NGF mRNA. These data strengthen a role for the reticular thalamic nucleus and NGF in PTZ kindling. © 1993 Wiley‐Liss, Inc.
Localization of trkB mRNA in postnatal brain development
Authors: Masana Y. , Wanaka A. , Kato H. , Asai T. , Tohyama M. 
Published: January 2005

AbstractWe investigated the localization of trkB mRNA, which encodes a putative component of high‐affinity brain‐derived neurotrophic factor (BDNF) or the neurotrophin‐3 (NT‐3) receptor, in the postnatal rat brain by in situ hybridization histochemistry. At birth, trkB mRNA was strongly expressed in various regions with the thalamus and cerebral cortex showing the strongest expression. As the rat grows, expression generally persisted or declined in most regions with the exception of the hippocampus where trkB mRNA expression increased during postnatal development. In the adult brain, trkB mRNA was detected in the olfactory system, cerebral cortex, hippocampal formation, amygdala, and cerebellar cortex. These findings, together with the developmental profiles of BDNF and NT‐3 mRNA expressions, suggest that trkB product (gp145trkB) mainly transduces NT‐3 signals early in the postnatal period, and BDNF signals later in the period. © 1993 Wiley‐Liss, Inc.
The protein phosphatase inhibitor okadaic acid increases axonal neurofilaments and neurite caliber, and decreases axonal microtubules in NB2a/d1 Cells
Authors: Shea T. B. , Paskevich P. A. , Beermann M. L. 
Published: January 2005

AbstractWhen cells were treated with dbcAMP for 3 days to induce the outgrowth of axonal neurites, the addition of the phosphatase inhibitor okadaic acid (0A; 5 nM) for the last 24 hr markedly increased neurofilament subunit immunoreactivity including phosphate‐dependent NF‐H epitopes in axonal neurites, increased axonal neurite caliber by approximately 30 %, but did not increase neurite contour length. Ultrastructural analysis demonstrated a >2‐fold increase in neurofilaments and indicated that neurofilaments were phosphorylated to a similar extent in the presence and absence of OA. Vimentin immunoreactivity, which undergoes down‐regulation during dbcAMP‐mediated differentiation, was not increased by OA. OA did not induce the precocious appearance of delayed phosphate‐dependent neurofilament epitopes suggesting that it did not induce the activation of additional neurofilament kinases. NF‐H subunits from cytoskeletons of OA‐treated cells were less susceptible to degradation by an endogenous calcium‐dependent protease, providing a possible mechanism for neuro filament accumulation during OA treatment. By contrast, OA decreased axonal neurite microtubules, and eliminated stabilized (acetylated) axonal microtubules. OA treatment at earlier times prevented and reversed neurite outgrowth. Despite increased deposition of phosphorylated neurofilaments, OA did not hasten the development of colchicine resistance to neurites, suggesting that stabilization of the axonal cytoskeletal lattice requires neurofilament‐microtubule interaction. © 1993 Wiley‐Liss, Inc.
Immunoreactivity of PMP‐22, P0, and other 19 to 28 kDa glycoprotens in peripheral nerve myelin of mammals and fish with HNK1 and related antibodies
Authors: Hammer J. A. , O'Shannessy D. J. , De Leon M. , Gould R. , Zand D. , Daune G. , Quarles R. H. 
Published: January 2005

AbstractMammalian peripheral nervous system (PNS) myelin contains several glycoproteins with molecular weights of 19 to 28 kDa, including the major 28 kDa P0 glycoprotein and a recently cloned protein called PMP22. Some glycoproteins in this Mr range in humans, cats and some other mammals react with HNK1, a mouse monoclonal antibody that identifies a carbohydrate epitope shared between the immune system and a number of adhesion proteins in the nervous system. A variety of antibodies to PO, PMP‐22, and the carbohydrate determinants reacting with HNK1 were used to characterize immunochemically these 19 to 28 kDa glycoproteins of cat PNS myelin. The HNK1‐reactive components include P0 and two slightly smaller 23 to 26 kDa proteins that are immunologically related to PO. However, HNK1 reacts most strongly with a lower molecular weight glycoprotein that does not react with the antibodies to P0 and was identified as PMP‐22. Since the carbohydrate structure reacting with HNK1 is generally expressed on adhesion molecules, this result suggests that PMP‐22 may function in cell‐cell or membranemembrane interactions. Furthermore, the related human anti‐MAG monoclonal lgM antibodies from patients with neuropathy also react strongly with PMP‐22, suggesting that it may be a target antigen in the pathogenesis of this disease. Purified PNS and CNS myelin from bony fish (toadfish and trout) were also shown to contain major glycoproteins, in the same 19 to 28 kDa Mr range, that react very strongly with HNK1. It is known that fish myelin has major proteins of this size that are immunologically and structurally related to mammalian P0, and it is demonstrated here that one of the strongly HNK1‐positive proteins reacted well with an antiserum raised to bovine P0. The presence of high levels of the adhesion‐related HNK1 epitope on these major myelin proteins of fish suggests that this carbohydrate structure may have played a role in the molecular evolution of myelin. © 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.
NTera 2 Cells: A human cell line which displays characteristics expected of a human committed neuronal progenitor cell
Authors: Pleasure S. J. , Lee V. M.‐Y. 
Published: January 2005

AbstractWe have identified a human cell line with a phenotype resembling committed CNS neuronal precursor cells. NTera 2/cl.D1 (NT2/D1) cells expressed nestin and vimentin, intermediate filament (IF) proteins expressed in neuroepithelial precursor cells, as well as MAP1b, a microtubule‐associated protein (MAP) expressed in human neuroepithelium. NT2/D1 cells also expressed the cell adhesion molecules NCAM and N‐cadherin which are thought to be important in cellcell interactions within the neuroepithelium. These NT2/D1 cells also expressed small amounts of NF‐L, α‐internexin, NF‐M, and MAP2c, indicating that they are committed to a neuronal fate. Previous studies have shown that, following RA treatment, a proportion of NT2/D1 cells terminally differentiate into neurons and that this occurs via an asymmetric stem cell mode of differentiation. In light of the identification of the neuroepithelial phenotype of NT2/D1 cells we decided to examine more closely the relationship of in vitro neurogenesis in NT2/D1 cells, during RA treatment to that of neurons in vivo. Three days after RA treatment, islands of NT2/D1 cells showed increased expression of neurofilament proteins and increased phosphorylation of NF‐M. By 10–14 days, these cells began to resemble neurons morphologically, i.e., with rounded cell bodies and processes. These neuronal cells were clustered into clumps which rested on top of a layer of progenitor cells. In this upper layer, the neurons began to express MAP2b and tau and extinguished their expression of mestin. Recently, we developed a method for obtaining pure cultures of neurons from RA treated NT2/D1 cells. The phenotype of these postmitotic neurons is clearly dissociated from that of the untreated NT2/D1 cells. Given the data obtained in this study and the characterization of the neurons derived from NT2/D1 cells, we propose that NT2/D1 cells are a committed human neuronal precursor cell line which retains some stem cell characteristics and is capable only of terminal differentiation into neurons. © 1993 Wiley‐Liss, Inc.
Early responses of PC‐12 cells to NGF and EGF: Effect of K252a and 5′‐methylthioadenosine on gene expression and membrane protein methylation
Authors: Kujubu D. A. , Stimmel J. B. , Law R. E. , Herschman H. R. , Clarke S. 
Published: January 2005

AbstractAlthough epidermal growth factor (EGF) and nerve growth factor (NGF) have markedly different biological effects on PC‐12 cells, many of the signaling events following ligand binding are similar. Both EGF and NGF result in the induction of the primary response gene egr‐1/TIS8 and increased methylation of a variety of membrane‐associated proteins as early as 5 min after EGF or NGF treatment using a methylation assay that detects methyl esters as well as methylated arginine residues. At 20 min after stimulation with these factors, the stimulation of methylation by NGF is greater than that of EGF, especially in the polypeptides of 36–42 and 20–22 kDA. To help dissect the pathways involved in these cellular responses, the protein kinase inhibitor K252a and the methyltransferase inhibitor 5′methylthioadenosine (MTA) were used. Both K252a and MTA inhibit NGF‐, but not EGF‐mediated, primary response gene expression. In contrast, MTA, but not K252a, can block NGF‐induced membrane associated protein methylation. These data suggest a role for differential protein methylation reactions in EGF and NGF signal transduction. © 1993 Wiley‐Liss, Inc.
Protein kinases modulate the sensitivity of hippocampal neurons to nitric oxide toxicity and anoxia
Authors: Maiese K. , Boniece I. R. , Skurat K. , Wagner J. A. 
Published: January 2005

AbstractMultiple processes lead to neuronal death after ischemia, but the generation of nitric oxide (NO) is a key component in this cascade of events. The mechanisms that regulate the extent of neuronal degeneration during anoxia and NO toxicity are multifactorial. Neuronal death may be modulated by the activity of signal transduction systems that influence the toxicity of NO or its metabolic products such as cGMP. The enzyme responsible for the production of NO, nitric oxide synthase (NOS), is phosphorylated by protein kinase C (PKC), the cAMP‐dependent protein kinase (PKA), and the calcium/calmodulin‐dependent protein kinase II (CaM‐II). We examined in primary cultured hippocampal neurons whether the protein kinases PKC, PKA, CaM‐II, and cGMP‐dependent protein kinase modified the toxic effects of anoxia and NO. Down‐regulation of PKC activity with PMA (1μM) increased hippocampal neuronal survival during anoxia and NO exposure from approximately 22% to 88%. Inhibitors of PKC activity 9H‐7, H‐8, sphingosine, and staurosporine also were neuroprotective. Down‐regulation of PKC activity increased survival during anoxia even in the presence of the NOS inhibitor, Nω‐methyl‐L‐arginine. Thus, although down‐regulation of PKC activity may increase neuronal survival by decreasing NOS activity, it also is likely that PKC contributes to ischemic neuronal death by mechanisms that are independent of NOS. Inhibition of the cGMP‐dependent protein kinase activity, but not the activity of the CaM‐II also was neuroprotective during NO administration. In contrast to the protective effects of inhibition of PKC and the cGMP‐dependent protein kinase, activation rather than inhibition of PKA increased hippocampal neuronal survival during NO exposure. These results indicate that neuronal survival during anoxia and NO exposure is linked to the modulation of PKC, PKA, and cGMP‐dependent protein kinase activity but is not dependent on the CaM‐II pathway. Understanding the involvement of PKC, PKA, and the cGMP‐dependent protein kinase in modulating the effect of neuronal death during ischemia and NO toxicity may help in directing future therapeutic modalities for cerebrovascular disease. © 1993 Wiley‐Liss, Inc.
Intracellular distribution of transgenic bacterial β‐galactosidase in central nervous system neurons and neuroglia
Authors: Friedrich V. L. , Holstein G. R. , Li X. , Gow A. , Kelley K. A. , Lazzarini R. A. 
Published: January 2005

AbstractBacterial β‐galactosidase is widely used as a marker for gene expression and in cell tracing experiments. In a survey of three transgenic mouse lines expressing β‐galactosidase in the central nervous system (CNS) under the control of different promotors, we find substantial variation in the intracellular distribution of the lacZ protein. In line MβP5, transgene β‐galactosidase expression is driven by a promoter/enhancer fragment from the oligodendrocyte‐specific myelin basic protein gene; however, electron microscopy of histochemically stained preparations revels transgene expression not only in oligodendrocytes but also in some neurons. Immunofluorescence and immunoperoxidase staining show the β‐galactosidase protein distributed throughout the perikaryal cytoplasm of oligodendrocytes and in processes reaching to myelin sheaths. By contrast, immunoreactive protein appears restricted in neurons to one or a few small perikaryal immunoreactive granules. The granules are visible in the electron microscope as amorphous inclusion bodies of moderate electron density and lack a limiting membrane. Histochemical staining patterns with X‐gal and Bluo‐gal echoed the protein distribution: diffuse distribution of enzyme protein yielded cells filled with substrate, while punctate enzyme distribution yielded restricted or punctate histochemical staining. Examination of two other lines using different promoter/enhancers to drive expression in the CNS showed both diffuse and punctate β‐galactosidase immunolocalization and histochemical staining. The amount of protein synthesized or other properties, yet unidentified, intrinsic to the target cells may determine the intracellular distribution of β‐galactosidase. In retroviral marking studies, clone members have been identified as those cells filled with X‐gal reaction product. This approach may underestimate both clone size and the minimum number of divisions separating the members of each clone. © 1993 Wiley‐Liss, Inc.
Neuron‐oligodendroglial interactions during central nervous system development
Authors: Hardy R. , Reynolds R. 
Published: January 2005

AbstractIt is well established that a variety of growth factors influence the differentiation of oligodendroglial lineage cells in culture, although little information is available concerning the role and source of these factors in vivo. Developing oligodendroglia are almost constantly in a neuronal environment and would be expected to respond to a variety of signals from neurons that affect their survival, migration, division, maturation and myelin production. However, very little is known about the specific interactions that occur between these two cell types. Here we review the experimental evidence for the influence of neurons on oligodendroglial differentiation, including studies on the effects of both soluble factors and contact dependent events. We also propose a scheme for the control of myelinogenesis via both internal and external signals. © 1993 Wiley‐Liss, Inc.
Expression of neuromodulin (GAP‐43) and its regulation by basic fibroblast growth factor during the differentiation of O‐2A progenitor cells
Authors: Deloulme J. C. , Laeng P. , Janet T. , Sensenbrenner M. , Baudier J. 
Published: January 2005

AbstractIn a recent work we have shown that neuromodulin (Nm, also known as GAP‐43), a protein kinase C substrate, previously believed to be expressed exclusively in neurons, is also present in glial cells. Here we investigated the expression of Nm and its mRNA in O‐2A glial progenitor cells (common precursor for oligodendrocytes and type‐2 astrocytes) during their development in secondary culture and under the influence of basic fibroblast growth factor (bFGF). The different stages of oligodendrocyte development were characterized by the expression of surface markers: A2B5, which identifies O‐2A glial precursor cells, and O4 and galactocerebroside (GC), which characterize later developmental stages. The number of cells expressing Nm (about 90% at culture initiation) decreased rapidly during the first 2 days and reached a plateau at around 30–40%. The level of Nm mRNA followed a similar kinetic. Immunocytochemistry demonstrated that at 4 days in vitro about 25–30% cells were A2B5,+, 30–40% Nm+, a high percentage (60–70%)O4 +, and 35–40% GC+. Nearly all of the morphologically immature A2B5+ cells expressed also the Nm antigen, very few of the O4+ cells still expressed Nm and almost no cells expressed both GC and Nm. Most O4+ cells developed a typical oligodendrocyte morphology and were essentially GC+. This study also showed that in the presence of serum, the A2B5+ Nm and 04+ Nm+ (GC−)xs cells retained their bipotentiality and differentiated into GFAP+ (glial fibrillary acidic protein) Nm+ type‐2 astrocytes.The bFGF was found to stimulate the proliferation of Nm+ 0–2A precursor cells and to increase the level of Nm mRNA. At 4 days under this culture condition the predominant cell type was A2B5+ and Nm+. Only 25–35% of the cells were O4+, but 90–95% of them were Nm+. Very few GC+ cells were visible in the presence of bFGF, but 20–40% of them were Nm+. These data indicate that Nm is essentially associated to glial O‐2A precursor cells and further confirm that bFGF blocks the differentiation of these cells. It is suggested that Nm plays a role in the plasticity (developmental potential) of the bipotential 0–2A progenitor cells. © 1993 Wiley‐Liss, Inc.
Cell blotting and isoelectric focusing of neuroblastoma‐derived heparin‐binding neurotrophic activities: Detection of basic fibroblast growth factor protein and mRNA
Authors: Wewetzer K. , Janet T. , Heymann D. , Unsicker K. 
Published: January 2005

AbstractNeuroblastoma cells have been shown to contain growth factors, which may be involved in the regulation of cell proliferation and/or differentiation. We have examined whether human IMR‐32 neuroblastoma cells store factors with a capacity to promote neuron survival and differentiation. Heparin affinity chromatography, cell blotting, and isoelectric focusing of IMR‐32 cell extracts revealed multiple neurotrophic activities at molecular weights of 16.8, 24.1, 39.0, 45.3, 52.3 and isoelectric points of 4.0, 5.0, 8.3, 9.0. Immunocytochemistry, immunoblotting, and radio‐immunoassay with specific antibodies suggests that one neurotrophic activity is immunologically identical with basic fibroblast growth factor (bFGF). This assumption is supported by Northern blot analysis, which shows a 6.0 kb bFGF transcript. © 1993 Wiley‐Liss, Inc.