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M Aubery

Publications and source records attributed to M Aubery.

16 recordsLinked to original sources
PubMed1992

Relationship between the content of [14C]glucose-derived monosaccharides in glycoprotein oligosaccharide chains and the state of enterocytic differentiation of HT-29 cells.

The HT-29 cell line derived from a human colon adenocarcinoma has a glucose-dependent state of differentiation which is negatively correlated with the presence of D-glucose in the culture medium. The contribution of glucose to the biosynthesis of N-glycan chains, as a function of the differentiation state of HT-29 cells, was shown by: (a) [14C]glucose incorporation by undifferentiated HT-29 cells being lower after 2 h and higher after 19 h of metabolic labeling than that by differentiated cells; (b) a lack of glucose in the culture medium of undifferentiated HT-29 cells diminishing [14C]glucose incorporation into glycan chains, but not changing the glucose distribution between lipid- and protein-linked saccharides; (c) glucose behavior in undifferentiated HT-29 cells being not related to mannose-glycan metabolism, as the high-mannose compounds labeled with glucose and observed by HPLC showing a different distribution associated with the duration of glucose labeling; and (d) glucose being interconverted into other monosaccharide-glycan constituents in proportions different in differentiated and undifferentiated cell populations.

Carbon Radioisotopes↗
PubMed1992

Swainsonine is a useful tool to monitor the intracellular traffic of N-linked glycoproteins as a function of the state of enterocytic differentiation of HT-29 cells.

After treatment with swainsonine, an inhibitor of both lysosomal alpha-mannosidase and Golgi alpha-mannosidase-II activities, analysis of [3H]mannose-labeled glycans showed that HT-29 cells, derived from a human colonic adenocarcinoma, displayed distinct patterns of N-glycan expression, depending upon their state of enterocytic differentiation. In differentiated HT-29 cells hybrid-type chains were detected, whereas undifferentiated HT-29 cells accumulated high-mannose-type oligosaccharide, despite our demonstration of Golgi alpha-mannosidase-II activity in both cell populations. Pulse/chase experiments carried out in the presence of swainsonine revealed that the persistence of high-mannose-type chains in undifferentiated HT-29 cells was the result of the stabilization of glycoproteins substituted with these glycans. These data suggest that in undifferentiated HT-29 cells, glycoproteins with high-mannose-type oligosaccharides are delivered to a degradative compartment containing swainsonine-sensitive alpha-mannosidase(s), whereas in differentiated HT-29 cells glycoproteins enter a compartment in which alpha-mannosidase II (Golgi apparatus) is present. Thus, this apparent dual effect of swainsonine on N-glycan trimming may reflect differences in the intracellular traffic of glycoproteins as a function of the state of enterocytic differentiation of HT-29 cells.

Adenocarcinoma↗
PubMed1992

Evidence for the presence of complex high-molecular mass N-linked oligosaccharides in intranuclear glycoproteins from HeLa cells.

Nonhistone proteins were extracted in 0.4 M NaCl from membrane-depleted nuclei of HeLa cells grown in the presence or the absence of [5,6-3H]fucose. Control experiments strongly suggest that most extracted proteins were indeed nuclear components. Several proteins, present in the 0.4 M NaCl nuclear extract, with M(r) ranging from 35,000 to 115,000 were identified on Western blots as fucosylated glycoproteins owing to their binding to the fucose-specific lectin, Ulex europeus agglutinin I. Results of experiments involving mild alkaline treatment and peptide N-glycosidase F digestion showed that the carbohydrate moieties of these fucosylated nuclear glycoproteins were N-linked to the polypeptide backbone. Analysis of the N-glycans revealed the presence of two populations of sialylated oligosaccharides on the basis of their relative molecular masses. The sensitivity of the high-M(r) oligosaccharides to endo-beta-galactosidase and their incorporation of [3H]glucosamine suggest that they could contain repeating N-acetyllactosamine units. [3H]Fucose incorporated into nuclei was confined to the nucleoli, as judged by autoradiography of sections cut through cells grown in the presence of [3H]fucose. Electron microscopy autoradiography showed that the fibrillar centers were never labeled, while silver grains were observed on the dense and the granular components of nucleoli. Taking into account of these data most nuclear fucosylated glycoproteins extracted in 0.4 M NaCl might be nucleolar ribonucleoproteins.

Blotting, Western↗
PubMed1992

Enzymatic activity and in vivo distribution of 5'-nucleotidase, an extracellular matrix binding glycoprotein, during the development of chicken striated muscle.

The ecto-enzyme 5'-nucleotidase isolated from chicken gizzard has previously been shown to be a potent ligand of two glycoproteins of the extracellular matrix, namely fibronectin and laminin. Using immunofluorescent labeling techniques we observed that 5'-nucleotidase codistributed with laminin during the development of chicken striated muscle. In contrast, ecto-5'-nucleotidase was only faintly detectable on cells surrounded by a matrix expressing high levels of fibronectin. This distribution pattern distinguished 5'-nucleotidase from the pluripotent extracellular matrix receptors, chicken beta 1-integrins, which are expressed equally well in muscle and connective tissue. In addition, the specific activity of striated muscle ecto-5'-nucleotidase was stable during development and increased markedly posthatching. At each age considered, this specific activity corresponded to an 80-kDa enzyme which was inhibited by alpha,beta-methyleneadenosine diphosphate or by a monoclonal antibody directed against the smooth muscle isoform of the enzyme. Previous in vitro studies have revealed that 5'-nucleotidase is involved in the spreading of various mesenchyme-derived cells, such as chicken embryonic fibroblasts and myoblasts, on a laminin substrate. A prerequisite to examining a potential in vivo role for 5'-nucleotidase as an extracellular matrix ligand was to study its distribution. In adult muscle, 5'-nucleotidase displayed a more restricted distribution than in embryo. Results show that, in vivo, 5'-nucleotidase is revealed by immunofluorescent labeling using poly- and monoclonal antibodies to chicken gizzard 5'-nucleotidase in two structures, the costameres and myotendinous junctions, which are closely related to the focal adhesion sites observed in cell culture.

5'-Nucleotidase↗
PubMed1979

Changes in the sensitivity of chick fibroblasts to Ricinus lectin (RCA I) toxicity in relation to the stage of embryo development.

The toxic effect of Ricinus lectin RCA I, as estimated by the inhibition of [3H]leucine incorporation, was investigated on chick-embryo fibroblasts at different stages of development. There appeared to be a differential susceptibility of chick-embryo fibroblasts to lectin RCA I. Fibroblasts from 16-day embryos were the most sensitive to its toxic effect in terms of both concentration and time, and cells from 8-day embryos were the least sensitive. This differential sensitivity to the toxic effect of lectin RCA I was closely related to the binding of the lectin: fibroblasts from 16-day embryos had more binding sites (1.5 x 10(7)/cell) with a high affinity than did 12-day (0.45 x 10(7)/cell) or 8-day embryos (0.2 x 10(7)/cell). Studies on the specificity and the removal of bound lectin RCA I by D-galactose indicated that the lectin binding was necessary but not sufficient in itself to cause the toxic effect and that the lectin needed to enter the cells in order to be toxic. The amount of lectin RCA I needed to induce a 50-60% toxicity enters fibroblasts of 16-day embryos more rapidly than those of 12- and 8-day embryos.

Animals↗
PubMed1979

[Electrophoretic profiles of proteins and glycoproteins of chick embryo fibroblasts during development].

The variations of proteins and glycoproteins of Chick embryo fibroblasts are studied during development. This investigation is carried out using polyacrylamide disc gel electrophoresis in SDS. Two glycoproteins of high apparent molecular weight (250,000 and 200,000) undergo quantitative modification: they increase from the 8th to 12th day of development and then remain unchanged to the 16th day. They are cell surface components as suggested by fluorescamine labelling and trypsin sensitivity. The results are discussed in terms of relationship between tumor- and embryo cells.

Animals↗
PubMed1979

Concanavalin A binding to amphibian embryo and effect on morphogenesis.

The effect of Concanavalin A (Con A) on morphogenesis in Pleurodeles waltlii has been studied. Embryos were incubated with various concentrations of the lectin for a period of 6 days. Three stages of development were examined, late blastula, young gastrula and late gastrula. In the presence of the lectin at a concentration of 200, 150 or 100 micrograms/ml morphogenic movements were delayed, altered and finally blocked. At lower concentrations, 50 or 25 microgram/ml, there was a slight delay in gastrulation, but in some cases development was normal. These findings indicate that Con A exerted an inhibitory effect on amphibian morphogenesis and there is evidence that the lectin effect was concentration dependent. The effects of Con A were specific since they were totally inhibited by alpha-methyl-D-mannopyranoside (0.05 M). The viability of the 24 h lectin-treated embryos was demonstrated by washing experiments. Labelled Con A binding to the embryos was investigated before and after discarding the vitelline membrane. The results suggest a direct interaction between Con A and the cell surface and this was confirmed by using fluorescein isothiocyanate Con A.

Animals↗
PubMed1978

Relationship between regeneration of cell surface glycoproteins in trypsin-treated chick embryo fibroblasts and cell adhesion to the substratum.

The ability of cells to adhere to a substratum was altered by treatment with trypsin but was restored after a 1.5-h culture. A concomitant incorporation of [3H] leucine and [14C] glucosamine in the trypsin-sensitive cell surface glycoproteins was observed and almost reached a plateau within 1.50 h following the treatment with trypsin.

Cell Adhesion↗
PubMed1978

Specific modifications of hepatoma cell-surface glycoproteins with enzymes. Effects on in vitro growth as investigated by the use of lectins.

The effects of enzymic treatment on the interactions between Zajdela's tumor cells and various lectins. Concanavalin A (ConA); Wheat Germ Agglutinin (WGA); Robinia lectin; have been studied. (1) The number of lectin-binding sites and the affinity constants were investigated. (2) The effects of the lectins on cell growth and [3H]thymidine incorporation were studied on untreated and enzyme-treated cells. It was observed that treatment of tumor cells with neuraminidase resulted in a change in the binding characteristics of each lectin. However, additional treatment of the cells with galactose oxidase had no further effect on lectin binding. ConA and Robinia lectin induced a decrease of the untreated tumor cell growth and a stimulation of the [3H]thymidine incorporation. This paradoxal result may be explained as a consequence of the stimulation of the [3H]thymidine uptake observed in the presence of lectins. The enzymatic treatments themselves did not change the cell growth although they did induce a change in the effect of ConA and Robinia lectin on cell growth and [3H]thymidine incorporation. As a result of neuraminidase treatment, the effects of ConA were totally suppressed but those of Robinia lectin only partially. Although WGA interacted with untreated and enzyme-treated cell surfaces, it had no effect on tumor cell growth nor [3H]thymidine incorporation. The results are discussed in terms of lectin transport.

Animals↗
PubMed1976

Embryo cell surfaces--lectin binding and cell proliferation.

The interaction between chick embryo fibroblasts and various lectins has been studied at different stages of embryo development. There is evidence that Robinia lectin, Dolichos lectin, and Concanavalin A decrease cell number and proportion of cells incorporating [3H] thymidine in case of 8- and 10-day-old chick embryo fibroblasts, whereas they stimulated the proliferation of 16-day-old embryo cells. No effect was noticed in 12-day cells. These results suggest that some cell surface changes occur during embryo development. The site number of Dolichos lectin remains the same during embryo development, and the affinity constant decreases. The site number of Robinia lectin and Concanavalin A decreases from the 8th to the 12th day of development, and slowly increases on the 16-day cells, the affinity constant remaining rather constant. The results indicate that the age-dependent effect of lectin on embryo cells could not be directly related to the number of lectin-binding sites. Competitive binding experiments revealed that Dolichos receptor sites were distincts from binding sites of Robinia lectin and Concanavalin A, and Robina receptor sites distinct from those of concanavalin A. Lectin effects on embryo fibroblasts were very specific as determined by inhibitory assays.

Animals↗
PubMed1976

Growth response to lectins in chick embryo cells at different stages of development.

We report here the effect of Robinia lectin and Concanavalin A on fibroblasts and liver cells from chick embryos between the 8th and the 20th day of development. This was observed in vitro after different times of cultivation. There is evidence that these lectins decrease cell number in cultures from young embryo cells but that they stimulate the proliferation of older embryo cells. The optimum concentration of either lectin was 3 mug/ml. No effect was observed on 12- and 14-day cells at the different concentrations of lectin used. The agglutination of fibroblasts by these lectins regularly decreased from the 8th to the 16th day of development. Liver cells however were agglutinated at no stage. These results could perhaps be explained in terms of cell surface changes either during the course of ontogeny or as a result of lectin treatment.

Agglutination↗
PubMed1975

Cell growth and thymidine incorporation changes induced by Dolichos lectin in embryo fibroblasts at various stages of differentiation.

We report here the effect of Dolichos lectin on chick embryo fibroblasts from embryos between 6th and 16th day of development. There is evidence that Dolichos lectin decreases cell number and proportion of cells incorporating tritium labelled thymidine in case of chick embryo fibroblasts of 6th, 8th and 10th day of development. Dolichos lectin stimulated the proliferation of 16-day old embryo cells. No effect was noticed on 12-day embryo cells at different concentrations of Dolichos lectin used. This lectin is specifically inhibited by N-acetyl-D-galactosamine and anti-Dolichos lectin serum. The difference in response by cells during different stages of embryonic development could perhaps be explained as some regulatory changes occurring on the cell surface.

Acetylgalactosamine↗