摘要:

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 gp75LNGFRand 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 t

ISSN:0360-4012    

DOI:10.1002/jnr.490370402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractWe have examined the region‐specific expression of mRNAs for four members of rat FGF receptor family, FGFR‐1, FGFR‐2, FGFR‐3, and FGFR‐4, in rat brain by in situ hybridization. The FGFR‐1, FGFR‐2, and FGFR‐3 mRNAs were expressed widely but differentially in the brain. However, the FGFR‐4 mRNA was not expressed in the brain. The FGFR‐1 mRNA was strongly expressed in several regions including the hippocampus, cerebellum, and pedunculoptine tegmental nucleus. The FGFR‐2 mRNA expression was high in the choroid plexus, and moderate in the fiber‐rich regions (the corpus callosum, external capsule, and internal capsule) and the olfactory bulb. The FGFR‐3 mRNA was expressed diffusely in the brain. We have also examined the cellular localization of these mRNAs in the brain. Although the FGFR‐1 mRNA was expressed preferentially in neurons, the FGFR‐2 and FGFR‐3 mRNAs were expressed preferentially in glial cells. The present findings that the FGFR‐1, FGFR‐2, and FGFR‐3 mRNAs were expressed widely but with region‐and cell‐specificity in the brain indicate that these receptors have different r

ISSN:0360-4012    

DOI:10.1002/jnr.490370403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractWe examined the binding of the gp120 envelope glycoprotein (gp120) of the human immunodeficiency virus (HIV‐1) to sulfatide (GalS), galactocerebroside (GalC), and GMI‐ganglioside (GMI). The gp120 glycoprotein bound to GalS but not to GalC or GMI by enzyme‐linked immunosorbent assay (ELISA) and by an immunospot assay on nitrocellulose paper. However, it bound to all three glycolipids by an immunospot assay on thin layer chromotography (TLC) plates. In studies to determine whether GalS could be a receptor for gp120 on the surface of cells, gp120 bound to GalS incorporated into the plasma membrane of lymphoid cells as determined by cytofluorometric analysis and immunofluorescence microscopy. These studies indicate that GalS may function as a receptor for gp120 and HIV‐1. © 1994 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490370404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractFerritin is the major iron storage protein and accounts for the majority of the iron in the brain. Thus, ferritin is a key component in protecting the brain from iron induced oxidative damage. The high lipid content, high rate of oxidative metabolism, and high iron content combine to make the brain the organ most susceptible to oxidative stress. The role of oxidative damage and disruption of brain iron homeostasis is considered clinically important to normal aging and a potential pathogenic component of a number of neurologic disorders including Alzheimer's disease and Parkinson's disease. Little is known, however, of the mechanism by which the brain maintains iron homeostasis at either the whole organ or cellular level. In this study we report the cellular distribution of the two isoforms of ferritin in the brain of adult subhuman primates. A subset of neurons immunolabel specifically for the H‐chain ferritin protein, whereas cells resembling microglia are immunolabeled only after exposure to the L‐chain ferritin antibody. Only one cell type immunostains for both H‐and L‐chain ferritin; these cells are morphologically similar and have the same distribution pattern as oligodendrocytes. Neither ferritin isoform is usually detected in astrocytes. These data indicate considerable differences in iron sequestration and use between neurons and glia and among neuronal and glial subtypes. This information will be essential in determining the role of each of these cells in maintaining general brain iron homeostasis and the relative abilities of these cells to withstand oxidative stress. © 1994 Wiley

ISSN:0360-4012    

DOI:10.1002/jnr.490370405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractLewisxis a cell‐surface carbohydrate antigen defined by the trisaccharide structure, Galβ 1→4 (Fucα 1→3) GlcNAc. Expression of Lewisxand sialyl‐Lewisxantigens 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 Lewisxantigen was expressed in more than 15% of astrocytes and 100% of oligodendrocytes, whereas it was not identified in neurons or in microglia. The oligomeric Lewisxantigen was undetectable in any cell types, while the sialylated oligomeric Lewisxantigen was expressed in more than 95% of microglia but not in any other cell types. The cell type‐specific expression of Lewisxand sialyl‐Lewisxantigens 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. ©

ISSN:0360-4012    

DOI:10.1002/jnr.490370406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

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 differe

ISSN:0360-4012    

DOI:10.1002/jnr.490370407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractIn order to determine the peptide bond specificity of calpain, human myelin basic protein (HMBP) was treated with purified calpain of bovine brain. Upon incubation, HMBP component I (HMBP‐1) was degraded into several peptides as demonstrated by sodium dodecy1 sulfate‐polyacrylamide gel electrophoresis. Component I was more susceptible to degradation than components II and III. HMBP degradation products were separated by high performance liquid chromatography (HPLC) and the cleavage sites in HMBP molecules were determined by peptide sequence analysis and by N‐ and C‐terminal analyses. The major cleavage site was found to be94Val‐95Thr with several minor cleavages at49Arg‐50Gly,18Ala‐19Ser,23His‐24Ala,27Gly‐28Phe,59Asp‐60Ser,70Gly‐71Ser,97Arg‐98Thr,110Ser‐111Leu,145Asp‐146Ala, and156Leu‐157Gly. These results indicate that calpain is involved in the limited proteolysis of human myelin basic protein and prolonged incubation causes further digestion of the large pep

ISSN:0360-4012    

DOI:10.1002/jnr.490370408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractRetinal cells from 7‐day‐old chicken embryos were cultured in the presence of a polyclonal anti‐GMI antibody, at low and high density in a “sandwich cell culture”. Cells that were about 80% neurofilament positive at all times, changed their morphology and emitted processes as controls. By examining immunocytochemical expression of gangliosides, cells cultured in the presence of the antibody maintained GD3 expression longer than controls, albeit the expression of the gangliotetraosylgangliosides (GTOG) was not considerably affected. This leads to an extension of the transient period in which differentiating cells coexpressed both types of gangliosides (GD3 and GTOG). At 3–4 days in vitro the relative synthesis of GD3 was about 30% higher and that of GD1a about 40% lower than in controls, indicating a delay in the shift of the synthesis pattern. Nevertheless, the pattern of ganglioside composition resembled at 4 days in vitro.Results indicate that the anti‐GMI antibody may modulate the expression and synthesis of gangliosides without a detectable decrease in neuritogenesis. Considering that the emission of neurites occurs in coexpressing GD3 and GTOG neurons, it is suggested that neuritogenesis could be irrespective of losing the G

ISSN:0360-4012    

DOI:10.1002/jnr.490370409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractThe tyrosine phosphorylation of glycoproteins in the adult and developing rat brain was investigated. Immunoblotting with anti‐tyr(P) antibodies identified a glycoprotein with an apparent Mr of 180,000 (GP180) as the major tyrosine‐phosphorylated protein in the concanavalin A (con A)‐binding fraction prepared from forebrain homogenates. This glycoprotein had the same electrophoretic mobility as the postysynaptic density (PSD)‐associated glycoprotein PSD‐GP180. Tyrosine‐phosphorylated GP180 was enriched 24‐fold in isolated PSDs relative tohomogenates. Digestion with endoglycosidase F/N‐glycosidase F demonstrated that GP180 present in total homogenates and PSD‐GP180 present in total homogenates and PSD‐GP180 present in isolated PSDs contained similar amounts of N‐linked oligosaccharide suggesting that they are the same glycoprotein. The tyrosine phosphorylation of GP180 in homogenates varied between brain regions with the highest levels occurring in cortical areas and the amygdala and low or undetectable amounts being present in hindbrain regions. Incubation of homogenates with adenosine triphosphate (ATP) resulted in the tyrosine phosphorylation of GP180 in all regions examined except the cerebellum and identified a second con A‐binding glycoprotein, GP110, which was phosphorylated on tyrosine. GP180 was not phosphorylated on tyrosine following the incubation of cerebellar homogenate, synaptic membranes, or PSDs with ATP. Tyr(P)‐GP180 was not detected prior to the onset of synaptogenesis, increased in parallel with the formation of synapses during the first 4 weeks of postnatal development of the frontal cortex and hippocampus, and then decreased 50–60% to adult levels. The results suggest that GP180 corresponds to the PSD glycoprotein PSD‐GP180 and are consistent with a role for this glycoprotein in synaptic development and signal transduction at the sy

ISSN:0360-4012    

DOI:10.1002/jnr.490370410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY

摘要:

AbstractPlectin is a high molecular weight protein originally identified and characterized as a major cytoskeletal component of the C6 rat glioma cell. Here we demonstrate by immunoblotting of crude intermediate filament (IF) protein preparations that plectin is a cytoskeleton‐associated component of the rat spinal cord. We then used avidin‐biotin peroxidase immunocytochemistry and indirect immunofluorescence to localize plectin within the adult rat central nervous system (CNS) and examine its distribution with respect to IF proteins. Plectin immunoreactivity is localized to all ependymal cells including the choroidal epithelial cells and tanycytes, Bergmann glial processes, radially oriented glial cells in the spinal cord, astrocytes in white matter, a subset of astrocytes in gray matter, a subset of motoneurons in the brainstem and spinal cord, and certain endothelial cells. Colocalization studies with neural If proteins show that plectin has a unique distribution pattern which most closely resembles, but is distinct from, that of vimentin. The few plectin positive neurons invariably also contain the neurofilament triplet proteins and peripherin, so that the ability of plectin to bind to the triplet proteins in vitro may reflect an in vivo interaction. The predominance of plectin at the inner ventricular boundaries of the nervous system as well as at the blood‐brain barrier is in line with the pattern of plectin expression in other tissues and suggests a general role for plectin in the maintenance of such junctional regions. © 1994 Wiley‐L

ISSN:0360-4012    

DOI:10.1002/jnr.490370411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1994

数据来源: WILEY