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A Faissner

Publications and source records attributed to A Faissner.

At least 91 records · Page 5Linked to original sources
PubMed1988

Biochemical characterization of different molecular forms of the neural cell adhesion molecule L1.

The neural cell adhesion molecule L1 is a phosphorylated, integral membrane glycoprotein that is recovered from adult mouse brain tissue by immunoaffinity chromatography as a set of polypeptides with apparent molecular masses of 200, 180, 140, and 80 kilodaltons (L1-200, L1-180, L1-140, and L1-80, respectively). It has been shown that L1-140 and the phosphorylated L1-80 is generated from L1-200 by mild proteolytic treatment of intact cells. In the present study we have investigated the structural relationships between the different molecular forms of L1 and their location with regard to the surface membrane. We could show that L1-200 has two preferred cleavage sites, one that generates the amino terminal, extracellularly exposed L1-140 and the carboxy terminal L1-80 that spans the membrane. Cleavage at the other site leads to the generation of the amino terminally located L1-180 and the membrane-attached, phosphorylated carboxy terminal L1-30. This site is cleaved during treatment of live cultured cells with broad-spectrum, protease-free phospholipase C (but not phosphatidylinositol-specific phospholipase C) or exposure to sodium azide or cyanogen bromide. Other conditions that cause damage to cells do not lead to the generation of L1-180 and L1-30, suggesting a particular cell-intrinsic cleavage mechanism. L1-180 is truly soluble in aqueous solutions, since it can be recovered from culture supernatants and in the supernatant of a crude membrane fraction after incubation for 2 h at 37 degrees C. Although trypsin treatment alone does not release L1-140 into the supernatant, combination of phospholipase C and mild tryptic treatment leads to the release of L1-140 and L1-50, the latter being most likely the extracellularly exposed domain of L1-80 that is complementary to the membrane-integrated phosphorylated L1-30. Phase separation experiments with Triton X-114 show that the released forms of L1-180 and L1-140 distribute into the aqueous phase, whereas they distribute into the detergent phase when in association with L1-200 or L1-80. However, when L1-80 is cleaved to yield the soluble L1-50 and membrane-anchored L1-30, L1-140 is released into the supernatant together with L1-50. A strong affinity of L1-200, L1-140, and L1-80 to each other is also indicated by the fact that they incorporate together into liposomes and separate only under strong detergent conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Monoclonal antibody detects carbohydrate microheterogeneity on the murine cell adhesion molecule L1.

The cell surface glycoprotein L1 is involved in neural cell interactions and shares with other adhesion molecules, i.e. the neural cell adhesion molecule N-CAM, the myelin-associated glycoprotein MAG and the J1 glycoproteins, an unusual carbohydrate structure designated L2/HNK-1. Recent evidence suggests that the L2/HNK-1 carbohydrate participates in adhesion. Since indirect evidence indicated that the L2/HNK-1 carbohydrate is not present on all molecules within a particular species of glycoproteins, it seemed pertinent to investigate this more directly by sequential immunoprecipitations. Here we show that the L2/HNK-1 epitope appears to be present on 35% of the L1 glycoproteins isolated from mouse brain. The epitope is restricted to the proteolytic fragment of L1 at the aminoterminal, extracellular domain in that it is detectable on L1-200 and L1-140, but absent from L1-80 and L1-50.

Animals↗
PubMed1987

The novel carbohydrate epitope L3 is shared by some neural cell adhesion molecules.

The monoclonal L3 antibody reacts with an N-glycosidically linked carbohydrate structure on at least nine glycoproteins of adult mouse brain. Three out of the L3 epitope-carrying glycoproteins could be identified as the neural cell adhesion molecules L1 and myelin-associated glycoprotein, and the novel adhesion molecule on glia. Expression of the L3 carbohydrate epitope is regulated independently of the protein backbone of these three glycoproteins. Based on the observation that out of three functionally characterized L3 epitope-carrying glycoproteins three fulfill the operational definition of an adhesion molecule, we would like to suggest that they form a new family of adhesion molecules that is distinct from the L2/HNK-1 carbohydrate epitope family of neural cell adhesion molecules. Interestingly, some members in each family appear to be unique to one family while other members belong to the two families.

Adenosine Triphosphatases↗
PubMed1985

Biosynthesis and membrane topography of the neural cell adhesion molecule L1.

The biosynthesis and membrane topography of the neural cell adhesion molecule L1 have been studied in cerebellar cell cultures by metabolic labeling and immunoprecipitation. Pulse and pulse-chase experiments with [35S]methionine show that L1 is synthesized in its high mol. wt. form, the 200 kd component. The lower mol. wt. components with 40, 80 and 140 K apparent mol. wts. can be generated by proteolysis in intact cellular membranes. Peptide maps generated by protease treatment of L1 isolated from adult mouse brain show that the 80 and 140 kd components are related to the 200 kd component, but not to each other. The 200, 80 and 40 kd components can be biosynthetically phosphorylated. The 140 kd component is not phosphorylated and not released from the surface membrane during tryspinization. The phosphorylated amino acid is serine. In the presence of tunicamycin the 200 kd component is synthesized as a 150 kd protein. Pulse-chase experiments in the presence of tunicamycin indicate that the carbohydrate moieties are predominantly N-glycosidically linked and that the contribution of O-glycosylation is minimal. The carbohydrate moieties are of the complex type as shown by treatment with endoglycosidase H. Since monensin inhibits processing of the carbohydrate moieties, the 200 kd component appears to be transported to the surface membrane via the Golgi apparatus.

Amino Acids↗
PubMed1985

Demonstration of immunochemical identity between the nerve growth factor-inducible large external (NILE) glycoprotein and the cell adhesion molecule L1.

The nerve growth factor-inducible large external (NILE) glycoprotein and the neural cell adhesion molecule L1 were shown to be immunochemically identical. Immunoprecipitation with L1 and NILE antibodies of [3H]fucose-labeled material from culture supernatants and detergent extracts of NGF-treated rat PC12 pheochromocytoma cells yielded comigrating bands by SDS-PAGE. NILE antibodies reacted with immunopurified L1 antigen, but not with N-CAM and other L2 epitope-bearing glycoproteins from adult mouse brain. Finally, by sequential immunoprecipitation from detergent extracts of [35S]methionine-labeled early post-natal cerebellar cell cultures or [3H]fucose-labeled NGF-treated PC12 cells, all immunoreactivity for NILE antibody could be removed by pre-clearing with L1 antibody and vice versa.

Adrenal Gland Neoplasms↗
PubMed1984

Synapse formation and synaptic activity in mammalian nerve-muscle co-culture are not inhibited by antibodies to neural cell adhesion molecule L1.

Co-cultures of rat myotubes and spinal cord explants from mouse embryos were maintained in the presence of Fab fragments of polyclonal antibodies to neuronal cell surface antigen L1. Microscopic observation showed that neurite outgrowth was not blocked by anti-L1. By intracellular recording, no effect was observed on the number of myotubes that showed endplate potentials, nor on the efficiency of synaptic contacts. As was demonstrated by indirect immunofluorescence, added Fab fragments remained bound to the neurite surface and were present in the medium for at least two days in culture, after which time antibodies were replaced during the medium change. Taken together, these observations show that L1 antigen is not involved in synapse formation between nerve and muscle.

Animals↗
PubMed1984

The neural cell adhesion molecule L1 is distinct from the N-CAM related group of surface antigens BSP-2 and D2.

The neural cell adhesion molecule L1 and the group of N-CAM related molecules, BSP-2 and D2 antigen, are immunochemically distinct molecular species. The two groups of surface molecules are also functionally distinct entities, since inhibition of Ca2+-independent adhesion among early post-natal mouse cerebellar cells by Fab fragments of both antibodies are at least additive, when compared with equal concentrations of the individual antibodies.

Animals↗
PubMed1984

Expression of neural cell adhesion molecule L1 during development, in neurological mutants and in the peripheral nervous system.

Neural cell adhesion molecule L1 consists of two glycoprotein bands of 140 and 200 kdaltons at all developmental stages studied (from birth to adulthood in murine cerebellum and cerebral hemispheres) and in the 4 neurological mouse mutants reeler, weaver, staggerer and Purkinje cell degeneration. In histological sections L1 antigen is detectable at birth in the Purkinje cell layer and fiber tracts in the prospective white matter, but not in the external granular layer. From postnatal day 4 onwards L1 antigen additionally appears in the inner part of the external granular layer, the zone of postmitotic premigratory granule cell neurons. The outer part of the external granular layer remains L1 antigen-negative until it disappears at approximately day 12. From then onwards, the antigen remains prominent in the nascent molecular layer and is less detectable in white matter and internal granular layer, the location of the cell bodies of postmigratory granule cells. The four neurological mouse mutants show development of L1 antigen expression analogous to the normal situation, despite an abnormal cellular architecture. In contrast to the central nervous system. Western blots of adult sciatic nerve show a more complex pattern of L1 immunoreactive bands. L1 antigen is detectable on most, if not all Schwann cells in histological sections of sciatic nerve from 17-day-old embryos. At postnatal day 2, only some Schwann cells appear L1 antigen-positive. From then onwards L1 seems most prominently associated with non-myelinating Schwann cells. In monolayer cultures of neonatal dorsal root ganglia the antigen is observed on the surface of neurons and of some Schwann cells. The mutant, trembler, shows a more immature staining pattern for L1 antigen in adult sciatic nerve.

Age Factors↗
PubMed1982

Analysis of polypeptides of the tree shrew (Tupaia) herpesvirus by gel electrophoresis.

The virion polypeptide composition of three independently isolated tree shrew herpesviruses (THV) was analysed by SDS-polyacrylamide slab gel electrophoresis and by a two-dimensional technique using isoelectric focusing. Two of the virus isolates analysed were from malignant tumours; the other isolate (THV, strain 1) was from an apparently healthy animal. The polypeptide patterns of the three purified Tupaia herpesvirus isolates were remarkably similar, each consisting of at least 35 polypeptides ranging in mol. wt. from 12,000 to 230,000. Whilst the majority of analogous polypeptides of the three viruses were of indistinguishable electrophoretic mobility, some (e.g. polypeptides of 82K to 86K) showed small differences in apparent mol. wt. which were characteristic of the virus strain. Comparative SDS-polyacrylamide gel electrophoresis made it possible to distinguish the Tupaia herpesvirus isolates from each other. At least five glycoproteins were found in purified THV virions. The two-dimensional electropherograms revealed at least 47 discernible protein spots, some of which were specific for a given THV isolate and which were detectable even in lysates of THV-infected cells.

Animals↗
PubMed1982

Analysis of Tupaia herpesvirus proteins by one- and two-dimensional gel electrophoresis.

The polypeptide composition of four Tupaia herpesvirus strains--of which two were isolated from malignant tumors--was analysed by one- and two-dimensional gel analysis. It was found that purified virions of the tree shrew consist of a least 37 viral polypeptides when determined by SDS polyacrylamide gel electrophoresis. The number of viral polypeptides increased to 49 when analysed by the two-dimensional technique with the molecular weights ranging from 12.000 to 230.000. Variations in the viral polypeptide patterns made it possible to differentiate between the different virus isolated even by the one-dimensional method. The two-dimensional technique allows the identification of virus-specific spots among the polypeptides of virus-infected cells. Radiolabeling experiments identified at least five glycoproteins which seem to reside on the surface of the virus envelope. In addition, neutralisation and immunodiffusion tests were performed which revealed cross-reactivities among the tupaia herpesvirus strains. Rabbit anti-tupaia herpesvirus sera did not neutralize other animal or human herpesvirus.

Animals↗
PubMed1980

Identification of polypeptides of the tree shrew (Tupaia) adenovirus.

The virion polypeptides of the Tupaia (tree shrew) adenovirus were analyzed by SDS-polyacrylamide slab gel electrophoresis and by isoelectric focusing. The viral proteins from either nonradioactive or 35S-methionine-labeled virions formed distinct patterns of at least 15 polypeptides which were different from those of known human and animal adenoviruses. Two-dimensional analyses revealed the presence of 18 discernible polypeptides.

Adenoviridae↗
PubMedDate not supplied

Neuron-glial interactions during the in vivo and in vitro development of the nigrostriatal circuit.

This paper examines a particular aspect of glial-neuronal interactions during central nervous system development: the possible influence of growing neurites on the expression of glial-associated extracellular matrix (ECM) molecules. In particular, using in vivo manipulations of the dopaminergic projections from the midbrain substantia nigra, as well as an in vitro model of the developing nigrostriatal circuit, we look at the reciprocal interactions between growing dopaminergic axons and astrocyte-derived ECM molecules in the striatum. Glial-derived glycoconjugates, including tenascin and a proteoglycan designated DSD-1, are developmentally expressed ECM molecules which have been shown to have different effects on immature neurons and their growing processes. Here we show that the glial expression of these ECM constituents in a target region (the caudate-putamen or neostriatum) may be affected by the presence or absence of an appropriate, maturing afferent projection (in this case, dopaminergic nigrostriatal axons). In general, our results reveal complex glial-neuronal interactions during the normal development of central nervous system circuits, and the ability to create in vivo and in vitro models which may be useful toward understanding these complex cellular and molecular interactions in degeneration and plasticity of the nigrostriatal circuit in diseases including Parkinson's.

Animals↗
PubMedDate not supplied

Neural cell adhesion molecules and myelin-associated glycoprotein share a common carbohydrate moiety recognized by monoclonal antibodies L2 and HNK-1.

Cell surface molecules have been implicated in cell interactions which underlie formation of the nervous system. The analysis of the functional properties of such molecules has profited from the combined use of antibodies and cell culture systems. It has been suggested that the interplay between these molecules modulates cell-to-cell interaction at critical developmental stages. In the mouse, N-CAM and L1 antigen have been shown to mediate Ca2+-independent adhesion among neural cells. N-CAM plays a role in fasciculation of neurites and formation of neuromuscular junction. L1 is apparently not involved in synaptogenesis, but in migration of granule cell neurones in the developing mouse cerebellar cortex. The two antigens are distinct molecular and functional entities which act synergistically in aggregation of neuroblastoma and early postnatal cerebellar cells. In view of a certain similarity in function between the two groups of molecules, it was not surprising to find that structural similarities are detectable by the monoclonal antibody L2. We show here that a carbohydrate moiety recognized by L2 and HNK-1 monoclonal antibodies, is present in mouse N-CAM and L1. The L2 epitope appears on all major neural cell types but not all N-CAM molecules express it. This heterogeneity points to a previously undetected molecular diversity which may have functional implications for modulating cell adhesion during development.

Animals↗
PubMedDate not supplied

The J1 glycoprotein--a novel nervous system cell adhesion molecule of the L2/HNK-1 family.

The neural cell adhesion molecules L1 and N-CAM share a common carbohydrate epitope that is recognized by the monoclonal antibodies L2 and HNK-1. The L2/HNK-1 epitope is also present on the myelin-associated glycoprotein (MAG) which is thought to mediate surface interactions between the axon and myelinating cell. Other, as yet unidentified, cell-surface glycoproteins are recognized by the two antibodies and are believed to belong to a family of neural cell adhesion molecules. To test this hypothesis, we have prepared polyclonal antibodies to a prominent member of the L2/HNK-1 family, the 160K (relative molecular mass (Mr)160,000) glycoprotein. Here we report that these antibodies, designated J1 antibodies, react with astrocytes and oligodendrocytes and interfere with neurone-astrocyte adhesion, but not with neurone-neurone or astrocyte-astrocyte adhesion. This result suggests the involvement of the J1 antigen in cell-cell interactions.

Animals↗
PubMedDate not supplied

Differential inhibition of neurone-neurone, neurone-astrocyte and astrocyte-astrocyte adhesion by L1, L2 and N-CAM antibodies.

The cell adhesion molecules L1, N-CAM and Ng-CAM have been implicated in cell-cell interactions among developing neural cells. L1 and N-CAM are structurally and functionally distinct molecular entities and act synergistically in mediating Ca2+-independent adhesion between re-aggregating early postnatal cerebellar cells. N-CAM has been reported to be neurone-specific in the chicken and to mediate fasciculation of neurites and of nerve-muscle interactions. L1, which in the central nervous system has been found only on post-mitotic neurones, mediates migration of granule cell neurones in the mouse cerebellar cortex. In view of the molecules' distinct effects on cell interactions, we wondered whether different neural cell types are involved in the actions of each molecule. Here we report that L1 antigen promotes neurone-neurone adhesion. N-CAM, which is expressed on both neurones and glia, mediates neurone-neurone, neurone-astrocyte and astrocyte-astrocyte adhesion. The L2 carbohydrate epitope shared between the two adhesion molecules seems to be involved in neurone-astrocyte and astrocyte-astrocyte adhesion and acts in a more than additive manner in N-CAM-mediated neurone-neurone adhesion.

Animals↗
PubMedDate not supplied

A unique mosaic in the visual cortex of the reeler mutant mouse.

Numerous studies have revealed abnormal cytoarchitectonics in the reeler mouse brain. In the present study, acetylcholinesterase (AChE) histochemistry has revealed a distinctive mosaic within the occipital cortex of the reeler mouse. The mosaic does not appear until after the second postnatal week, perhaps in association with eye opening. AChE staining in the visual cortex of normal littermates does not exhibit a mosaic pattern, but rather, is present within bands or laminae. The AChE mosaic in reeler persists into adulthood. Immunocytochemical staining of the tenascin glycoprotein, an astrocyte-derived extracellular matrix molecule that is concentrated in boundaries around emerging functional patterns in the CNS, reveals a boundary-mosaic pattern in the first postnatal week. Dil axonal tracing in normal versus reeler mice indicates that the thalamocortical projections may also be associated with the AChE mosaic. The observation that a mosaic is unique to the occipital cortex of reeler mice suggests that it may evolve through abnormal cell and molecular interactions in the mutant cortex that normally lead to the development of functional visual representations.

Acetylcholinesterase↗