Glycopeptide of P0 protein inhibits homophilic cell adhesion: competition assay with transformants and peptides.
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Amino Acid Sequence↗
Biomedical subjects
H Asou
Publications and source records attributed to H Asou.
Cell adhesion molecule L1 guides cell migration in primary reaggregation cultures of mouse cerebellar cells.
We demonstrate a new assay in vitro using reaggregated cerebellar neurons in order to test the role of the L1 molecule in migration events. Cells other than neurons were eliminated in these cultures. Cerebellar neuron reaggregates plated on L1 molecule substrates migrated at rates similar to those observed in vivo. This migration was blocked by anti-L1 antibody. These findings suggest that this culture could provide a useful system with which to directly study relationships between neuron migration and adhesion molecules.
Animals↗
Glycopeptide of P0 protein inhibits homophilic cell adhesion. Competition assay with transformants and peptides.
Expression of major myelin glycoprotein P0 by P0 cDNA transfection into C6 glioma cells promoted homophilic cell adhesion of the cells. After the dissociated cells were incubated for various times, the number of particles at each time point was measured. The total number of particles decreased to 24% in 60 min for transformant (C6P0) cells, in contrast to only 68% for control (C6P0') cells. To confirm the homophilic mechanism of adhesion, mixed-cell aggregation experiments were performed. Among the four synthetic peptides corresponding to a part of the P0 sequence used, only peptide 3 (residues 90-96), which contained a carbohydrate attaching site, caused considerable inhibition of cell aggregation (approximately 50%). In addition, the glycopeptide (residues 91-95) obtained from bovine P0 markedly inhibited cell aggregation (by approximately 85%).
Amino Acid Sequence↗
Functional expression of a full-length cDNA coding for rat neural cell adhesion molecule L1 mediates homophilic intercellular adhesion and migration of cerebellar neurons.
Neural cell adhesion molecule L1 is postulated to be involved in cell-cell interaction, neurite elongation, fasciculation of axons, cell migration, and myelination. To determine the function of L1 directly, we have transfected rat L1 cDNA into mouse fibroblast L cells. Stable transformants expressing L1 showed uniform surface expression of the molecule without phenotypic changes. Dispersed L1-expressing transfectants aggregated with faster kinetics than control cells in a homophilic manner. Divalent cations were not required for this cell aggregation. L1-transfected cells markedly enhanced neuronal cell adhesion and migration in co-culture with rat cerebellar neurons. These results indicate that L1 is involved in a determinant step of neural development through molecular interactions.
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A novel monoclonal antibody against carbohydrates of L1 cell adhesion molecule causes an influx of calcium in cultured cortical neurons.
We have studied the function of carbohydrates of the L1 molecule, a member of the immunoglobulin superfamily of adhesion molecules, using a novel monoclonal antibody, mAb-L1(2E12), against L1 molecule. This antibody was specific for the 200 kDa component of mouse L1 molecule and its epitope was N-linked for complex-type oligosaccharides. The mAb-L1(2E12) was found to induce a rise in intracellular Ca2+ concentration ([Ca2+]i) in cultured mouse embryonic cortical neurons. The rise in [Ca2+]i was dependent on the concentrations of mAb-L1(2E12). The rise seemed to be due to an influx of extracellular Ca2+ as EGTA treatment abolished it. Both cadmium and nifedipine blocked the effect of mAb-L1(2E12), suggesting the Ca2+ influx was through voltage-operated Ca2+ channels, particularly L-type Ca2+ channels. These results provide an important insight for understanding the mechanisms by which oligosaccharides of the L1 molecule influence various functions of neural cells.
Animals↗
Monoclonal antibody that recognizes the carbohydrate portion of cell adhesion molecule L1 influences calcium current in cultured neurons.
A monoclonal antibody (mAb), 2E12, against the neural cell adhesion molecule L1 recognized the 200 kDa component of L1. The epitope of L1 reacting with mAb 2E12 was localized in its carbohydrate chain, judging from the results of experiments on glycopeptidase F treatment. The physiological effect of adding mAbL1 (2E12) to cultured mouse dorsal root ganglion neurons was studied using patch-clamp techniques. The binding of mAbL1 (2E12) to the neurons expressing L1 molecule induced an inward current inhibited by calcium channel blockers such as nifedipine and Lanthanum. It was also found that the mAbL1 (2E12) leads to a rise in the intracellular Ca2+ concentration ([Ca2+]i) in cultured neurons. This rise seems to be due to an influx of extracellular Ca2+, since treatment with EGTA abolished those phenomena. L-type calcium channel blockers such as nifedipine and cadmium, as well as inward current, blocked the effect of mAbL1 (2E12). These results suggest that the carbohydrate chain of L1 glycoprotein is directly involved in the induction of calcium current, and that the L1 molecule may play a prominent role in regulation of the Ca2+ channel.
Animals↗
Gradient expression of neural cell adhesion molecule (NCAM) in the pontine migratory stream of fetal rats.
Immunohistochemical localization of a neural cell adhesion molecule (NCAM) was examined in the subpial pontine migratory stream of the fetal rat with a monoclonal antibody specific for the rat NCAM, MAb-AF11. Although the pontine cell strand showed weaker expression of NCAM than the parenchymal areas of the brainstem, within the cell strand, NCAM-immunoreactivity was somewhat greater in the anterior part of the stream near the neurons' destination than the caudal part. The weak NCAM gradient in the pontine migratory stream may contribute to formation of the pontine cell strand and the basal pontine gray.
Animals↗
Involvement of neuronal cell surface molecule B2 in the formation of retinal plexiform layers.
The B2 molecule is a 220 kd neuronal cell surface protein of Xenopus, recognized by monoclonal antibody B2 (MAb B2). Immunohistochemistry using MAb B2 revealed that the B2 molecule was expressed in both the inner and outer plexiform layers within the neural retina. During development of the neural retina, the B2 molecule first appeared at stages 35/36 in the newly formed plexiform layers. When embryonic eyes were cultured in the presence of anti-B2 antiserum (Fab fragments), the formation of the retinal plexiform layers was impeded. These data suggest that the cell surface molecule B2 plays a role in the development of retinal plexiform layers.
Animals↗
The cell adhesion molecule L1 has a specific role in neural cell migration.
L1-transfected L cells show a markedly enhanced ability for neuronal cell binding and promotion of neuron migration compared with control L cells. Further, when purified L1 was used as a culture substrate for neurons, it was found to promote neuronal adhesion and enhance the speed of migration of cerebellar neurons from reaggregated cultures, indicating that it is involved in a determinant step of neural cell migration.
Animals↗
Selective binding of [3H]NMeQNB to a subpopulation of muscarinic receptors in single smooth muscle cells induces a temperature dependent decrease of receptor-[3H]NMeQNB complex.
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Animals↗
Cytogenetic 2; 18 and 18; 22 translocation in chronic lymphocytic leukemia with juxtaposition of bcl-2 and immunoglobulin light chain genes.
The majority of follicular lymphoma cells carry the typical chromosome translocation 14;18, which juxtaposes the bcl-2 gene to the immunoglobulin heavy-chain (IgH) gene. Variant translocations of the bcl-2 gene to the Ig lambda or Ig kappa gene have been found by molecular biological techniques in a significant fraction (approximately 10%) of chronic lymphocytic leukemia (CLL). However, there have been no reports describing the presence of cytogenetic 18;22 and 2;18 translocations in CLL, in spite of extensive karyotypic studies. We present here two cases of CLL, one with cytogenetically detected t(2;18)(p11;q21) and the other with the t(18;22)(q21;q11). The molecular analysis revealed that these translocations juxtaposed the bcl-2 and immunoglobulin light-chain (IgL) genes. The t(18;22) broke the 5' flanking region of the bcl-2 gene and juxtaposed to the immunoglobulin lambda light-chain (Ig lambda) gene in a head-to-head configuration, as in the cases previously described. In the case of the t(2;18), the bcl-2 gene and immunoglobulin kappa light-chain (Ig kappa) gene were juxtaposed in a head-to-tail configuration, which is opposite to that expected from the orientation of the genes on chromosomes. The breakpoint was located within the 5' untranslated region of the bcl-2 gene. The results presented here indicate that the bcl-2/immunoglobulin light-chain (IgL) gene juxtaposition seen in a fraction of CLL is the result of cytogenetically detectable reciprocal chromosome translocations 2;18 and 18;22.
Base Sequence↗
Molecular cloning of cell adhesion molecule L1 from human nervous tissue: a comparison of the primary sequences of L1 molecules of different origin.
Complementary DNA for the human neural cell adhesion molecule L1 was cloned and sequenced: the deduced amino acid sequence consists of 1257 amino acid residues containing six repeats of the immunoglobulin C2 domain and five repeats of the fibronectin type III domain. The intracellular domain of human L1 is highly conserved as compared to mouse, but not identical to L1 cloned from human melanoma cells, suggesting the existence of alternative forms in the same species.
Amino Acid Sequence↗
Molecular cloning of cDNA encoding the rat neural cell adhesion molecule L1. Two L1 isoforms in the cytoplasmic region are produced by differential splicing.
We have isolated and sequenced a full-length cDNA encoding the rat neural cell adhesion molecule L1. The deduced amino acid sequence as a whole shows high homology to mouse L1 sequence. In addition to this complete form of L1, we found an isoform, L1cs, which lacks four amino acid residues (RSLE) in the cytoplasmic domain and probably is derived from the same single L1 gene by tissue-specific alternative splicing. While L1 mRNA was predominantly expressed in the brain, L1cs mRNA was found exclusively in peripheral nervous tissue. Differential splicing in the highly conserved cytoplasmic domain may play an important role in modulating the function of L1 in different cells.
Amino Acid Sequence↗
Establishment of a human acute myeloid leukemia cell line (Kasumi-1) with 8;21 chromosome translocation.
A novel leukemic cell line with an 8;21 chromosome translocation, designated as Kasumi-1, was established from the peripheral blood of a 7-year-old boy suffering from acute myeloid leukemia (AML). The Kasumi-1 cells were positive for myeloperoxidase showing a morphology of myeloid maturation. The response in proliferation assay was observed in the culture with interleukin-3 (IL-3), IL-6, granulocyte colony-stimulating factor (G-CSF), and granulocytemacrophage CSF (GM-CSF), but not with IL-1 or IL-5. Neither granulocytic nor eosinophilic maturation was observed in the liquid culture by the addition of dimethyl sulfoxide, G-CSF, or IL-5, respectively. In contrast, induction of macrophagelike cells was seen by the addition of phorbol ester. This is the first report of a human AML cell line with t(8;21) that has characteristics of myeloid and macrophage lineages. The cell line could be a useful tool for elucidating the pathophysiology of AML with t(8;21).
Antigens, CD↗
Changes of endogenous ganglioside composition in mouse cerebrum primary cultures following long-term exposure to phorbol ester.
Changes in endogenous gangliosides caused by phorbol 12-myristate 13-acetate (PMA, 162 nM) were examined using mouse cerebrum primary cultures. The total ganglioside content was significantly decreased by 25% and 40% in PMA-treated cultures compared to control cultures on days 1 and 8, respectively. In addition, changes in the pattern of ganglioside composition were also observed in which the percentage of GM1 and GD3 in total gangliosides was significantly increased and, in contrast, the percentage of GD1a and GT1b was reduced. Treatment of neurons with PMA induced the change of morphology. These results suggest that the decrease in the total ganglioside content and changes in ganglioside composition produced by long-term exposure to PMA are related to the appearance of neuronal cell aggregation and neurite fasciculation.
Animals↗
[Molecular construction of Philadelphia chromosome and its relation to the clinical features].
In 1960, Nowell and Hungerford found, for the first time, a minute chromosome at the metaphase in chronic myelocytic leukemia (CML) cells, which was called Philadelphia chromosome (Ph1 chromosome) later. Ph1 chromosome was considered to be specific for the disease and was frequently used as an important marker for the definite diagnosis. However, in mid-1970s, some cases with acute lymphocytic leukemia (ALL) were also found to have Ph1 chromosome in the leukemic cells. Therefore, Ph1 chromosome seemed to be non-specific for the diagnosis of CML. In 1980s, molecular-biology techniques were applied in the fields of leukemia research. As a result, clear differences were demonstrated between the two diseases (CML and ALL with Ph1 chromosome, respectively) at the molecular level using oncogene concept. In this review, molecular-genetic constructions of ABL, BCR and BCR-ABL hybrid genes in CML, as well as m-BCR-ABL hybrid gene in Ph1 positive ALL are focused in detail. Relationship between these molecular-genetic changes with the clinical features and the mechanism of cell growth in these cells with BCR-ABL or m-BCR-ABL hybrid genes are also discussed.
Chromosome Fragility↗
Localization of ganglioside GM1 with biotinylated choleragen.
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Animals↗
Morphological changes and neural cell adhesion molecule expression in mouse cerebrum primary cultures following long-term exposure to phorbol ester.
The effect of phorbol 12-myristate 13-acetate (PMA) on development of brain cells in culture was investigated. Chronic treatment of brain cells from fetal ICR mouse with PMA resulted in a time-dependent loss of specific [3H]phorbol 12,13-dibutyrate binding, generally called 'down-regulation'. In contrast to control culture, neurons cultured in PMA (162 nM)-containing medium exhibited aggregation and neurite fasciculation, and then the neural cell adhesion molecule (N-CAM) was expressed selectively on neurons. Also, the number of astrocytes, which were positively stained with anti-glial fibrillary acidic protein antibody, decreased by treatment with PMA. These results suggest that the normal development of cultured brain cells is interrupted by PMA treatment, which may involve protein kinase C (PKC) in the differentiation of neural cells and cell-cell (neuron-neuron, neuron-astrocyte etc.) interaction as PKC is believed to be a receptor for PMA and is down-regulated by chronic treatment with PMA.
Animals↗