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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cholinergic pathway ascending from the nucleus basalis magnocellularis (NBM) to the cortex has been implicated in several important higher brain functions such as learning and memory. Following infarction of the frontoparietal cortical area in the rat, a retrograde atrophy of cholinergic cell bodies and fiber networks occurs in the basalocortical cholinergic system. We have observed that neuronal atrophy in the NBM induced by this lesion can be prevented by intracerebroventricular administration of exogenous nerve growth factor (NGF) or the monosialoganglioside GM1. In addition, these agents can upregulate levels of cortical choline acetyltransferase (ChAT) activity in the remaining cortex adjacent to the lesion site. Furthermore, an enhancement in cortical high-affinity 3H-choline uptake and a sustained in vivo release of cortical acetylcholine (ACh) after K+ stimulation are also observed after the application of neurotrophic agents. Moreover, these biochemical changes in the cortex are accompanied by an anatomical remodeling of cortical ChAT-immunoreactive fibers and their synaptic boutons.
Mol Neurobiol 1992
PMID:Trophic factor effects on cholinergic innervation in the cerebral cortex of the adult rat brain. 128 34

The fluorescence method has been used to investigate ricin and its isolated subunits interaction with some model membranes. Three liposome types were used as a model of biological membrane: 1) liposomes constructed from lecithin and cholesterol (9:1, M:M) 2) from ganglioside receptors GM1 and 3) from the mixture of GM1, lecithin and cholesterol (1:9:1). Interaction of the protein with liposome evokes changes in the parameters of both intrinsic protein fluorescence and fluorescence of the covalently bound dansyl. Binding constants were calculated from a decrease of the intrinsic fluorescence intensity as well as from the changes in the dansyl rotation anisotropy. Measurements were carried out at neutral and acidic pH. There was good correlation of the results obtained by different methods. It was shown that association constants were different for intact ricin and its subunits. The constants also depend on liposome composition and pH of the solution. The present study has demonstrated that interaction of ricin with liposome is accounted for not only by receptor centers but also by other hydrophobic regions of ricin that are inaccessible in the native toxin and may represent the region of the subunits interaction.
Mol Biol (Mosk)
PMID:[Interaction of the toxic plant protein--ricin, with model membranes. A fluorescence method of study]. 140 16

1. No difference was observed in the in vitro growing ability of granule cells isolated from hypothyroid or normal rat brain. When granule cells were taken from hypothyroid rat brain and grown in normal culture medium containing 10% fetal calf serum, they behaved similarly to the granule cells obtained from normal rat brain. 2. In both cases there were progressive losses of in vitro growing ability of the granule cells with the age of the animal and it became impossible to grow them when derived from 21 days or older animals. 3. A marked decrease in cell surface GM1 was observed when the cells were maintained under thyroid hormone-deficient conditions in culture. 4. Anti-GM1 antibody was found to inhibit significantly the migration of granule cells along the astrocyte fibers. 5. These results indicate that GM1 has an important role in thyroid hormone-dependent postnatal brain maturation in rat.
Cell Mol Neurobiol 1992 Dec
PMID:Thyroidal influence on the cell surface GM1 of granule cells: its significance in cell migration during rat brain development. 149 Feb 75

We studied antibody responses after immunization with ganglio-series gangliosides against 10 strains of inbred mice, including Balb/c, C57BL/6, A/J, C3H/HeN, C3H/HeJ, CBA/N, AKR/N, NZB/N, DBA/2 and nu/nu Balb/c. Twelve gangliosides having NeuAc as their sialic acid moiety (GM4, GM3, GM2, GM1, GD3, O-Ac-GD3, GD2, GD1a, GD1b, GT1a, GT1b and GQ1b), four gangliosides having NeuGc (GM3, GM2, GM1 and GD3) and four asialo-gangliosides (GA4, GA3, GA2 and GA1) were injected intravenously adsorbed to Salmonella minnesota. The antibody titers of the mice sera were determined by an enzyme-linked immunosorbent assay and an immune adherence assay. Antibody responses were found to depend not only on the ganglioside used as an immunogen but also on the mouse strain. Gangliosides having a trisaccharide sequence (NeuAc alpha 2----8NeuAc alpha 2----3Gal-) such as GD3, GD2, GD1b, GT1a and GQ1b, in particular O-Ac-GD3, induced high-titer antibody responses, whereas those having a disaccharide sequence (NeuAc alpha 2----3Gal-) such as GM4, GM3, GM2, GM1, GD1a and GT1b induced low-titer antibody responses. On the other hand, gangliosides with NeuGc developed minimum titers. In contrast, asialogangliosides induced much higher responses than the corresponding gangliosides. The differences in ceramide portions of these gangliosides did not appear to be involved in inducing antibody responses. Mice could be divided into three groups according to the magnitude of their antibody responses: Group 1, those that produce the highest antibody responses (C3H/HeN and A/J); Group 2, those that demonstrate moderate antibody titers (Balb/c, C57BL/6, DBA/2 and nu/nu Balb/c); and Group 3, those that make minimum responses (AKR/N, C3H/HeJ, CBA/N and NZB/N). The pattern of reactivity to the various gangliosides was similar in all the strains tested.
Mol Immunol 1992 May
PMID:Antibody responses to ganglio-series gangliosides in different strains of inbred mice. 158 31

Highly ordered two-dimensional crystals of cholera toxin B-subunit pentamers have been grown by specific interaction with planar lipid films containing monosialoganglioside GM1. Electron diffractograms of frozen-hydrated crystals show diffraction peaks extending to beyond 4 A, while electron images diffract to 8 A. A two-dimensional projected structure of cholera toxin B-subunit-GM1 complex has been calculated at 9 A resolution by combining electron diffraction and image data. Crystals present an approximate pgg projection symmetry, with unit cell dimensions a = 119(+/- 1) A, b = 123(+/- 1) A, gamma = 90 degrees. Each pentameric assembly presents two concentric rings of electron scattering density, separated by an area of lower density. The outer and inner rings are centered at 25 A and and 11 A from the pentamer centre, respectively. The apparent projected density of the outer ring is larger than that of the inner ring. We propose that the outer and inner density rings correspond respectively to the peripheral beta-sheet arrangement and the central alpha-helix barrel, recently identified in the crystal structure of the heat-labile enterotoxin from Escherichia coli.
J Mol Biol 1992 Jul 05
PMID:A 9 A two-dimensional projected structure of cholera toxin B-subunit-GM1 complexes determined by electron crystallography. 161 52

The effect of murine recombinant interferon-gamma (IFN-gamma) on cell-mediated cytotoxicity against tumor cells in vitro and in vivo was investigated using a spontaneously developed, weakly immunogenic, syngeneic murine mammary adenocarcinoma, designated JC, as the target. Preincubation of JC tumor cells with IFN-gamma increased the susceptibility of lysis by both cytotoxic T lymphocytes and interleukin-2 (IL-2)-induced lymphokine-activated killer cells in an IFN-gamma dose-dependent manner. A direct injection of IFN-gamma (10,0000 U/d) daily for 5 consecutive days into the JC tumor nodule on the backs of BALB/c mice reduced the tumor growth in comparison with that of the control group. This antitumor activity was further enhanced by combination with a simultaneous intraperitoneal injection of IL-2 (300,000 IU/d) daily for 5 consecutive days. Phenotypic examination of tumor-infiltrating lymphocytes after injection of IFN-gamma plus IL-1 revealed an increased percentage of the cells expressing asialo GM1, L3T4, and IL-2 receptors. Additionally, an enhanced expression of major histocompatibility complex class I molecules on the JC tumor cells was detected. These results indicated that a direct injection of IFN-gamma into the tumor accompanied with the administration of IL-2, by enhancing cell-mediated immunity of the hosts and expression of major histocompatibility complex class I antigens on target cells, will be of potential clinical value.
Mol Biother 1992 Mar
PMID:Enhanced cell-mediated cytotoxicity by interferon-gamma and interleukin-2 against syngeneic murine mammary adenocarcinoma. 162 74

Phosphoinositide-specific phospholipase C and adenylyl cyclase were studied in brain cortical membranes from cats with GM1 and GM2 gangliosidosis. In contrast to brain cortical membranes from unaffected control cats, phospholipase C acting against exogenously supplied phosphoinositide substrates did not respond to stimulation by GTP gamma S, carbachol or fluoroaluminate in cortical membranes of cats with gangliosidosis. However, the enzyme was activated by calcium in membranes from affected cats to the same extent as in membranes from control cats. Basal adenylyl cyclase activity was increased 3-fold in cortical membranes of cats with GM1 and GM2 gangliosidosis, compared with unaffected sibling controls. Fluoroaluminate was equally effective in stimulating adenylyl cyclase in controls and in membranes of affected and normal cats. In addition, GppNHp was able to inhibit the forskolin-activated enzyme both in membranes from cats with gangliosidosis and sibling controls. These data suggest that the activation of phosphoinositide-specific phospholipase C in brain membranes by guanine nucleotide binding proteins is markedly impaired in GM1 and GM2 gangliosidoses.
Brain Res Mol Brain Res 1991 Oct
PMID:Altered phosphoinositide-specific phospholipase C and adenylyl cyclase in brain cortical membranes of cats with GM1 and GM2 gangliosidosis. 166 24

For the electron microscopic identification of asialo GM1-positive cells, fresh-frozen sections fixed with cold acetone and PLP-fixed vibratome sections of adult rat livers were prepared immunocytochemically using the avidin-biotin-peroxidase complex method. Asialo GM1-positive cells were located mainly in the sinusoids, and rarely in Glisson's sheath and portal veins. In the sinusoids, most pit cells, showing the ultrastructural characteristics of large granular lymphocytes (LGL), were positive for asialo GM1 but a few pit cells were asialo GM1-negative. There were several, morphological differences between asialo GM1-positive and -negative pit cells. The asialo GM1-negative pit cells were smaller and had less-developed cell organelles and fewer dense granules, suggesting a more immature stage of development. Almost all the monocytes, segmented neutrophils and eosinophils, and small or large lymphocytes in the sinusoids also showed positive reaction for asialo GM1. In Glisson's sheath, in addition to pit cells and lymphocytes, mast cells were also positive for asialo GM1. In contrast, fixed cells such as liver parenchymal cells, endothelial cells, Kupffer cells and Ito cells within the liver lobules, as well as biliary epithelial cells, smooth muscle cells, fibroblasts, endothelial cells and pericytes in Glisson's sheath were all negative for asialo GM1. Thus, cell surface asialo GM1 expression is not specific for pit cells (LGL) in the rat liver.
Virchows Arch B Cell Pathol Incl Mol Pathol 1991
PMID:Immunoelectron microscopic identification of asialo GM1-positive cells in adult rat liver. 168 55

The plasmid pBRD026, which directs expression of the B subunit of the Escherichia coli heat-labile toxin (LTB), was modified so that DNA encoding epitopes could be inserted at the 3' end of the gene. An oligonucleotide linker containing restriction sites for BglII and SpeI was inserted at the SpeI site at the 3' end of the LTB gene to form plasmid pFV1. This linker also encodes the amino acid sequence Gly-Pro-Gly-Pro which we propose acts as a 'hinge' between the LTB and the foreign epitope. Oligonucleotides specifying an epitope from the Bordetella pertussis P.69 outer membrane protein were cloned into pFV1 to form pFV169. The resultant fusion protein (LTB69) was partially purified from the periplasm of E. coli strains in a soluble pentameric form which could bind GM1 gangliosides. Mice immunized intranasally with purified LTB69 produced antibodies against both LTB and the P.69 protein. In addition, ELISPOT assays demonstrated the presence of LTB-specific and P.69-specific antibody-secreting cells in the lungs of immunized mice.
Mol Microbiol 1991 Jun
PMID:Intranasal immunization using the B subunit of the Escherichia coli heat-labile toxin fused to an epitope of the Bordetella pertussis P.69 antigen. 172 57

A hybrid protein consisting of the Escherichia coli lipoprotein signal sequence attached to the mature sequence of the B subunit of heat-labile enterotoxin (Lipo-EtxB) was expressed in yeast and E. coli. Analyses of cell lysates from Saccharomyces cerevisiae and E. coli expressing the protein revealed that both organisms were able to assemble Lipo-EtxB into oligomers that were (i) stable in the presence of sodium dodecyl sulphate, (ii) resistant to proteinase K degradation, and (iii) able to bind to GM1-ganglioside receptors. Each of these properties are characteristic of the wild-type B subunit pentamer produced in E. coli. Assembly of Lipo-EtxB was found to be unaffected in a sec18 mutant of S. cerevisiae, which possesses a temperature-sensitive defect in protein transport from the endoplasmic reticulum (ER) to the Golgi apparatus, but was found not to assemble in a sec53 mutant, which causes the misfolding of proteins targeted to the ER. A kar2-1 mutation with a defect in the yeast homologue of BiP caused an 18-fold reduction in Lipo-EtxB assembly at the non-permissive temperature in S. cerevisiae. However, introduction of the wild-type KAR2 gene on a plasmid into the kar2-1 mutant completely suppressed the inhibition of Lipo-EtxB assembly. This provides the first evidence that KAR2 facilitates the assembly of an oligomeric protein in yeast and thus implicates KAR2 as a 'molecular chaperone'. The possible mechanisms of enterotoxoid assembly in E. coli and S. cerevisiae are discussed.
Mol Microbiol 1991 Nov
PMID:Targeting and assembly of an oligomeric bacterial enterotoxoid in the endoplasmic reticulum of Saccharomyces cerevisiae. 177 57


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