bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunological determinants of nerve growth factor involved in p140trk (Trk) receptor binding
Authors: Nanduri J. , Vroegop S. M. , Buxser S. E. , Neet K. E. 
Published: January 2005

AbstractMonoclonal anti‐NGF antibodies that specifically inhibit the biological activity of mouse β‐NGF were used to study the structural determinants involved in the interaction of NGF with its receptors gp75LNGFR and Trk. None of the three antibodies–N60, M15, and 27/21–showed any reactivity toward denatured NGF. Three experimental methods–radioim‐munoassay (RIA), enzyme‐linked immunoassay (ELISA), and slot blots–detected no significant cross reactivity between the antibodies and BDNF or NT‐3. RIA showed that M15 and N60 recognize the same or an overlapping antigenic site, but 27/21 recognizes a different epitope. Only 27/21, and not N60 or M15, immunoprecipitated β‐NGF crosslinked to LNGFR receptor. Thus, the epitope recognized by 27/12 does not overlap the LNGFR receptor binding site. N60, M15, and 27/21 all block binding of NGF to Trk in a manner consistent with competitive inhibition. Purified Fab fragments of N60 and M15 gave similar results to the intact antibodies. The other subunits present in the 7S complex of NGF, i.e. the α and γ subunits, competitively inhibited binding of antibodies to β‐NGF. Only the γ subunit inhibited phosphorylation of Trk and biological activity of β‐NGF. These findings suggest that the M15, N60, and 27/21 antibodies bind to a specific site on the surface of NGF where they competitively inhibit binding to the Trk NGF receptor. The region encompassing the N‐terminus, the C‐terminus, and the loop on the surface of β‐NGF containing residues 60–80 is proposed as important for binding to the Trk receptoe. © 1994 Wiley‐Liss, Inc.
Differential expression of Lewisx and sialyl‐Lewisx antigens in fetal human neural cells in culture
Authors: Satoh J. , Kim S. U. 
Published: January 2005

AbstractLewisx is a cell‐surface carbohydrate antigen defined by the trisaccharide structure, Galβ 1→4 (Fucα 1→3) GlcNAc. Expression of Lewisx and sialyl‐Lewisx antigens in primary cell cultures isolated from fetal human brains of 12‐15 weeks gestation was investigated by double immunolabelling with antibodies against monomeric Lewisx (4C9), oligomeric Lewisx (FH4), and sialylated oligomeric Lewisx (FH6) antigens and cell type‐specific markers. The monomeric Lewisx antigen was expressed in more than 15% of astrocytes and 100% of oligodendrocytes, whereas it was not identified in neurons or in microglia. The oligomeric Lewisx antigen was undetectable in any cell types, while the sialylated oligomeric Lewisx antigen was expressed in more than 95% of microglia but not in any other cell types. The cell type‐specific expression of Lewisx and sialyl‐Lewisx antigens in fetal human glial cells suggests that these fucose‐containing carbohydrate molecules play roles in intercellular recognition between distinct cell types during the development of the human central nervous system. © 1994 Wiley‐Liss, Inc.
Functional identification of integrin laminin receptors that mediate process outgrowth by human SY5Y neuroblastoma cells
Authors: Choi E. S.‐H. , Rettig W. J. , Wayner E. A. , Srour M. L. , Clegg D. O. 
Published: January 2005

AbstractTreatment of the human neuroblastoma cell line SY5Y with nerve growth factor (NGF) induces terminal neuronal differentiation of a subpopulation of cells which can be selected by treatment with a DNA synthesis inhibitor. We have examined the interactions of navie (untreated) and NGF‐differentiated SY5Y cells with laminin, and identifid integrin receptors that mediate laminin‐induced process outgrowth. Differentiated cells displayed a greater capacity for process extension, which correlated with increased expression of integrin laminin receptors. Both naive and differentiated cells expressed integrins α1/β1, α2/β1, and α3/β1 but the differentiated population expressed about 5‐fold higher levels of α1/β1 and about 2‐fold nore α2/β1 and α3/β1 on their surface. Function blocking monoclonal antibodies were used to identify integrin receptors mediating process outgrowth. The anti‐α1 monoclonal antibodies were used to identify intergrin receptors mediating process outgrowth. The anti‐α1 moniclonal antibody SR84 was shown to block α1 function and inhibit process outgrowth on laminin. Despite the presence of multiple integrins which have been shown to bind laminin in other cell types, α1/β1 mediated the majority of process outgrowth in both naive and differentiated cells, with a minor role played by α3/β1. These data indicate that α1/β1 function is requried for process outgrowth on laminin by SY5Y cells and suggest that increased expression may be a crucial aspect of neuronal differentiation. © 1994 Wiley‐Liss, Inc.
Proteolipid protein interactions in transfectants: Implications for myelin assembly
Authors: Sinoway M. P. , Kitagawa K. , Timsit S. , Hashim G. A. , Hashim G. A. , Colman D. R. 
Published: January 2005

AbstractThe proteolipid proteins (PLP and DM20) are major constituents of CNS myelin, but how they are delivered to and organized within the oligodendrocyte plasma membrane is incompletely understood. We have expressed both PLP and DM20 singly or together in a host cell line, HeLa. In either DM20 or PLP transfectants, at early time points (24 hours), the expressed proteins are found within intracellular compartments. In DM20 transfectants, the protein is delivered to the plasma membrane by 48 hours. In HeLa cells, PLP remains intracellular when expressed in the absence of DM20; only when it is coexpressed with DM20 is it transported to the plasma membrane. In cotransfectants, PLP can also be localized to organelles involved in both the protein biosynthetic and the endocytic pathways. Since, in HeLa cells at least, the delivery of PLP to the plasma membrane is facilitated by the coexpression of DM20, we suggest that the two proteins interact intracellularly to form a complex. In some PLP/DM20 cotransfectants, the proteolipids are concentrated in regions of cell‐cell contact. The regional accumulation of these proteins at cell‐cell interfaces is highly reminiscent of the behavior in transfected cells of another myelin protein, Po, and certain cadherin polypeptides, both of which have readily demonstrable membrane adhesive properties. Our data suggests that at certain stoichiometric ratios, proteolipids can become stablized at cell surfaces to form adhesive bonds. © 1994 Wiley‐Liss, Inc.
Intracellular transport and sorting of the oligodendrocyte transmembrane proteolipid protein
Authors: Gow A. , Friedrich V. L. , Lazzarini R. A. 
Published: January 2005

AbstractDelineating the properties and functions of the major central nervous system myelin proteins has been the focus of intensive research for decades. For PLP, this task has been confounded by its unusual properties, the complexity of the cellular membrane in which it resides, and the absence of a functional assay for the protein. The development of new experimental paradigms in which to study PLP may shed fresh light on the properties and functions of this intrinsic membrane protein. In the present communication we have used indirect, double label, immunofluorescence, and confocal microscopy to examine the distribution of PLP in Cos‐7 cells transfected with an expression vector bearing the human PLP cDNA. Our results show that PLP is synthesized in the rough endoplasmic reticulum of transfected cells and passes through the Golgi apparatus to the cell surface. These results are consistent with previous studies showing PLP reaches the cell surface by transport through the secretory pathway. Levels of PLP at the cell surface are modest, most likely because protein deposited in this compartment can be endocytosed and subsequently transported to perinuclear lysosomes. Similar results are reported in the companion communication by Sinoway et al. (J Neurosci Res, 37:551–562, 1994). Using transfected HeLa cells they show that DM20 alone and PLP coexpressed with DM20 assume appropriate conformations for transport to the cell surface.The presence of PLP in subcellular compartments beyond the endoplasmic reticulum in Cos‐7 cells indicates that the protein achieves a conformation appropriate for transport in the absence of other oligodendrocyte‐specific factors; however, accumulation of large amounts of PLP in the cytoplasmic membrane compartment may require interactions with such glial‐specific factors. Thus, the transfection paradigm described herein should prove a useful tool for investigating the folding and sorting of wild type and mutant forms of PLP as well as its membrane topology and posttranslational processing.
Retinal ganglion cell survival in vitro maintained by a chondroitin sulfate proteoglycan from the superior colliculus carrying the HNK‐1 epitope
Authors: Nichol K. A. , Everett A. W. , Schulz M. , Bennett M. R. 
Published: January 2005

AbstractWe recently reported evidence implicating a superior colliculus‐derived chondroitin sulfate proteoglycan (SCCP) in the trophic support of cultured retinal ganglion cells (Schulz et al., 1990). In the present work we show preparations of the SCCP to be reactive with an antibody (CS‐56) to chondroitin sulfate types A and C and with the HNK‐1 antibody. Reaction with the HNK‐1 antibody allowed us partially to purify the native proteoglycan by immunoaffinity chromatography. HNK‐1 reactive material was further processed by a combination of molecular sieve chromatography in the presence of 4M guanidine HCL followed by anion exchange chromatography to yield a product that migrated electrophoretically as a single band in polyacrylamide gel with an apparent molecular weight of not less than 400k. The SCCP, when added to a fully defined culture medium, maintained the survival of the vast majority (80%) of the ganglion cells over a 16 hr culture period with 86% of these cells showing a profusion of processes; few ganglion cells (10%) survived in the absence of the proteoglycan. Electrophoretic analysis of nonreduced preparations of the molecule did not reveal any low molecular weight silver stained components that may have remained associated with the molecule after guanidine HCL treatment. However, two bands corresponding to molecular weights of around 60 and 80 k were reproducibly obseved on polyacrylamide gels following electrophoresis of the molecule in the presence of β‐mercaptoethanol. Our findings provide further evidence suggesting a role for a chondroitin sulfate proteoglycan carrying the HNK‐1 epitope in the trophic support of central neurones. © 1994 Wiley‐Liss, Inc.
Peripheral myelin protein‐22 expression in charcot‐marie‐tooth disease type 1a sural nerve biopsies
Authors: Hanemann C. O. , Stoll G. , D'Urso D. , Fricke W. , Martin J. J. , Van Broeckhoven C. , Mancardi G. L. , Bartke I. , Müller H. W. 
Published: January 2005

AbstractPeripheral myelin protein‐22 (PMP22) is expressed in myelinating Schwann cells and shows significant homology to murine growth arest‐specific gene gas3. Charcot‐Marie‐Tooth disease type 1a (CMT1a) is a common hereditary demyelinating neuropathy. Recently it was demonstrated that the gene for PMP22 is duplicated in CMT1a patients. A gene dosage mechanism has been postulated to cause CMT1a. According to this hypothesis, the increase in copy number of PMP22 gene would lead to an elevated expression of PMP22 and thereby cause the demyelinating phenotype of CMT1a. In the present communication we analyzed PMP22 mRNA and protein expression in sural nerve biopsies from CMT1a patients and normal controls. We show that PMP22 mRNA expression in CMT1a is not uniform. We found both elevated as well as normal PMP22 mRNA levels in patients. Interestingly, the highest PMP22 mRNA level was found in the least affected patient. In contrast to the mRNA levels, PMP22 was clearly reduced in all CMT1a patients as shown by immunohistochemistry. Thus the CMT1a phenotype may not be strictly correlated with increased PMP22 mRNA and protein expression. Possible roles of PMP22 in the pathogenesis of CMT1a are discussed. © 1994 Wiley‐Liss, Inc.
Molecular cloning and expression of a δ‐opioid recetpor from rat brain
Authors: Abood M. E. , Noel M. A. , Farnsworth J. S. , Tao Q. 
Published: January 2005

AbstractWe have isolated and characterized a rat δ‐opioid receptor. The deduced amino acid sequence (372 aa) closely resembles the murine δ‐opioid receptor, DOR‐1. In fact, 97% of the amino acid residues are conserved between the two species, while 93% of the nucleic acid residues are identical. A 6 kb mRNA was detected in rat cortex using rat DOR‐1 as a probe. When expressed in COS cells, the clone shows high‐affinity opioid binding with selectivity for δ‐opioids. The rat δ‐opioid receptor cDNA clone will be a useful tool for studying the function of δ‐opioid receptor in rats. Wiley‐Liss, Inc.
(–)‐Deprenyl alters the survival of adult murine facial motoneurons after axotomy: Increases in vulnerable C57BL strain but decreases in motor neuron degeneration mutants
Authors: Oh C. , Murray B. , Bhattacharya N. , Holland D. , Tatton W. G. 
Published: January 2005

AbstractThe effect of (–)‐deprenyl on the survival of axotomized adult murine facial motoneurons was investigated. Previously, (—)‐deprenyl was shown to increase the number of rat facial motoneurons (FMns) surviving after axotomy at postnatal day 14, apparently by compensating for the loss of muscle‐derived trophic factor. In the present study, three different strains of adult mice—A/J, C57BL/6J, and a congenic substrain of the C57BL/6J mice, the C57BL/Mnd mutants—underwent unilateral facial nerve transection. FMns were counted from serial sections taken through the entire length of the facial nuclei ipsilateral and contralateral to the facial nerve transections in animals sacrificed 21 days after axotomy. Subgroups of C57BL/6J and Mnd mutants were treated with either saline or 1.0 mg/kg (—)‐deprenyl for 21 days. Another subgroup of Mnd mutants were treated with the metabolites of (—)‐deprenyl, a mixture of (—)‐amphetamine and (—)‐methamphetamine, at a dosage equimolar to 1.0 mg/kg (—)‐deprenyl.The number of surviving facial motoneurons in the A/J strain was 90% of unlesioned, control values which supports previous findings that adult FMns receive adequate trophic support and thus can survive loss of muscle‐derived trophic support. In the C57BL/6J strain, the facial motoneuron survival was 35% and (—)‐deprenyl increased the survival to 50.5%. Mnd mutants showed 62.4% survival; however, (—)‐deprenyl decreased the number of motoneurons to 54.9% and amphetamine and methamphetamine treatment further decreased the motoneuron survival to 41.1%.These findings show that FMns in the Mnd mutants and their parental strain, C57BL/6J mice, show greater vulnerability to axotomy as compared to other adult strains of mice. The vulnerability is similar to that found in early postnatal life. (—)‐Deprenyl increases the survival of the axotomized C57BL/6J FMns but its major metabolites, (—)‐methamphetamine and (—)‐amphetamine, further decrease FMn survival in the C57BL/Mnd mutants, possibly due to the induction of neurotoxic proteins causing programmed neuronal death. The efficacy of (—)‐deprenyl in increasing the survival of damaged neurons would be expected to decrease as dosage increased above the dosage sufficient to induce maximum neuronal rescue (approximately 0.01 mg/kg) but would decrease as the dosage exceeded that necessary to produce toxic concentrations of the metabolites of (—)‐deprenyl (1.0 mg/kg in this study). © 1994 Wiley‐Liss, Inc.
Direct immunocytochemical localization of 5‐hydroxytryptamine receptors in the adult rat spinal cord: A light and electron microscopic study using an anti‐idiotypic antiserum
Authors: Ridet J.‐L. , Tamir H. , Privat A. 
Published: January 2005

AbstractIn the present study, we performed the immunodetection of serotonergic (5‐HT) receptor subtypes in the spinal cord by using an anti‐idiotypic antiserum (TH8) at light and electron microscopic levels. This antibody has been shown to recognize 5‐HT1B, 5‐HT1C, and 5‐HT2 receptor subtypes (Tamir et al.: J Neurochem 57:930–942, 1991). The TH8 immunoreactivity was observed in the dorsal and ventral horns of the gray matter. Light microscopy revealed that small cell bodies located in laminae I–III of the dorsal horn were intensely immunolabeled. A more homogenous and discrete staining was also observed throughout the entire dorsal horn. In the ventral horn, motoneurons were also immunoreactive (IR). Peroxidase deposits were observed as numerous patches covering the motoneuronal surface. Numerous interneurons were moderately and homogeneously immunostained.With the electron microscope, most of the labeled structures were identified as neurons (dendrites and perikarya) in both the dorsal and ventral horns. In the dorsal horn, immunoreactivity was present in dendrites and neuronal perikarya. A large majority of the immunoreactivity found in dendrites was not associated with synaptic differentiations. Indeed, the dendrites, in which peroxidase deposit was seen, were not locally involved in synapses. Very scarce synaptic varicosities were observed in close apposition with IR dendrites. In the ventral horn, TH8 immunoreactivity was present in dendrites, with an accumulation of peroxidase deposit on the active zone of synapses, facing presynaptic membranes. Both the postsynaptic membrane and the submembrane area were IR. In addition, a few astroglial fine processes were immunostained; most of them were observed in the dorsal horn. Scarce IR astroglial profiles were observed in the ventral horn. These observations show that such an antiserum constitutes a useful tool for the ultrastructural analysis of 5‐HT receptor distribution. Finally, correlation between the immunocytochemical localization of 5‐HT receptor subtypes and the modes of 5‐HT transmission in the spinal cord (wiring and volume transmissions) is discussed in the present report. © 1994 Wiley‐Liss, Inc.
Restricted hypotonic swelling of peripheral nerve myelin in streptozocin‐induced diabetic rats
Authors: Kirschner D. A. , Eichberg J. 
Published: January 2005

AbstractExperimental diabetic neuropathy includes the non‐enzymatic glycosylation (or glycation) of the major proteins of peripheral nerve myelin. We have used X‐ray diffraction to determine whether such glycation affects myelin membrane structure and interactions in peripheral nerves from experimental diabetic rats. Streptozocin at 60 mg/kg was injected intraperitoneally to induce diabetes; controls were pair‐fed and age‐matched. Animals were sacrificed periodically from 2 weeks to after 1 year. The dissected sciatic nerves were tied off and incubated overnight at room temperature in hypotonic saline of defined pH and ionic strength or in distilled water. Such treatments have been shown to result in systematic changes of myelin period, which can be detected using X‐ray diffraction, and which may indicate alterations in inter‐membrane interactions owing to changes in composition. We observed no differences in repeat periods between control and diabetic nerves at pH 4.0 and 7.4, and ionic strength 0.01, 0.02, 0.06, 0.15, and 0.18; however, we did detect a significant difference (P <.02) in their maximum extent of swelling in distilled water: control nerves showed a period of 292 Å (s.d. 23 Å; n = 12) compared to 272 Å (s.d. 19 Å; n = 11) for diabetic nerves. To determine whether this difference in swelling was due to an alteration in the properties of the apposed, extracellular surfaces of the myelin membranes or to the connective tissue in peripheral nerve, we compared the X‐ray patterns from peripheral nerve myelin isolated by sucrose density gradient centrifugation from sciatic nerves of diabetic and control rats. No difference in the patterns was observed. Since the maximum extent of myelin membrane swelling in peripheral nerves is limited by the collagen, our results suggest that the collagen in the nerves of diabetic rats is less elastic or more densely packed than in the controls, most likely due to N‐glycation‐mediated cross‐linking. © 1994 Wiley‐Liss, Inc.
Multiple interactions of aluminum with neurofilament subunits: Regulation by phosphate‐dependent interactions between C‐terminal extensions of the high and middle molecular weight subunits
Authors: Shea T. B. , Beermann M. L. 
Published: January 2005

AbstractExposure of individual purified neurofilament (NF) proteins to AlCl3 alters their electrophoretic properties in a time‐ and concentration‐dependent manner, as visualized by their failure to migrate into SDS gels. Co‐incubation of purified high (NF‐H) and middle (NF‐M) but not low (NF‐L) molecular weight NF subunits prevents this AlCl3‐induced alteration in electrophoretic migration. This latter finding suggested that specific interactions between NF‐H and NF‐M other than filament formation influenced their interaction with AlCl3. Co‐incubation of the 160 kDa α‐chymotryptic cleavage product of NF‐H (corresponding to the highly phosphorylated C‐terminal sidearm domain) with native NF‐M prevented alteration in subunit electrophoretic migration by AlCl3. By contrast, intact, dephosphorylated NF‐H subunits were unable to prevent AlCl3‐induced alteration of native NF‐M electrophoretic migration. Taken together, these findings suggest that phosphate‐dependent interactions between the sidearm extensions of NF‐H and NF‐M diminish the ability of AlCl3 to associate with either subunit in a manner that alters their electrophoretic migration. This interaction of NF‐H and NF‐M sidearms is SDS‐sensitive, while AlCl3‐induced alteration in electrophoretic migration of individual subunits is SDS‐resistant. Addition of SDS to mixtures of NF‐H and NF‐M subunits disrupted the protective effect, and promoted AlCl3‐induced alterations in subunit electrophoretic migration. These findings support and extend the current hypothesis that the ability of aluminum to interact with NF subunits is a function of subunit phosphorylation, assembly, and extent of neurofilament‐neurofilament cross‐linking. © 1994 Wiley‐Liss, Inc.
SR13/PMP‐22 expression in rat nervous system, in PC12 cells, and C6 glial cell lines
Authors: De León M. , Nahin R. L. , Mendoza M. E. , Ruda M. A. 
Published: January 2005

AbstractSR13/PMP‐22 is a protein that was identified after screening a sciatic nerve cDNA library. Our study focused on comparing the level and pattern of expression of SR13/PMP‐22 protein and RNA. Northern blot analysis revealed that although SR13/PMP‐22 mRNA was present in all nervous tissues and cells studied, levels were at least seven fold higher in the sciatic nerve and the spinal cord. During sciatic nerve postnatal development and maturation, the SR13/PMP‐22 mRNA was detected at 2 days after birth, reached a maximal level at day 24, and decreased to 1/3 of the maximum in adult animals. Nerve transection reduced the level of SR13/PMP‐22 mRNA to less than 5% in the segment distal to the nerve injury. Experiments using in situ hybridization localized the SR13/PMP‐22 mRNA in Schwann cells. Schwann cells present in the vicinity or distal to the nerve cut repressed the signal for the message. In situ hybridization experiments also demonstrated that dorsal root ganglia satellite cells contained the message for SR13/PMP‐22. The SR13/PMP‐22 antisera used in our study showed a complex pattern of staining. As expected, the SR13/PMP‐22 antibody peptide 1 immunoreacted with the sciatic nerve sheath. However, immunocytochemistry of the dorsal root ganglia revealed that the staining was contained in the neuron's cell body and processes and also in satellite cells. We also identified immunoreactive cell bodies and fibers in the spinal cord dorsal horn. Tissue culture studies demonstrated that SR13/PMP‐22 mRNA is induced in NGF treated PC12 but not in C6 glioma cell lines grown under experimental conditions that stimulated cell growth arrest. Our experiments suggest that SR13/PMP‐22 may have some other function(s) in addition to its hypothesized role in peripheral myelination. © 1994 Wiley‐Liss, Inc.