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Biomedical subjects

Y Courtois

Publications and source records attributed to Y Courtois.

At least 199 records · Page 11Linked to original sources
PubMed1983

Interaction of bovine epithelial lens (BEL) cells with extracellular matrix (ECM) and eye-derived growth factor (EDGF). I. Effects on short-term adhesiveness and on long-term organization of the culture.

A growth factor (EDGF) derived from the retina controls the proliferation and shape of adult bovine epithelial lens (BEL) cells in vitro as well as extracellular matrix (ECM) assembly. In order to analyse this mechanism and the specificity of the interactions between BEL cells and the extracellular matrix we have investigated the adhesion and growth of BEL cells on various substrata (fibronectin, laminin, ECM). BEL cells treated with EDGF adhered more slowly to plastic Petri dishes than untreated cells, in part due to EDGF inhibition of fibronectin deposition. The untreated BEL cells spread less well on ECM or laminin than on fibronectin-coated plastic. The preferential adhesiveness of BEL cells on fibronectin vs laminin was confirmed by attachment experiments performed on replicas of SDS-PAGE of these proteins. However, in long-term cultures, 8 days after seeding, BEL cells were very differently arranged on plastic or on ECM. ECM by itself did not increase the proliferation rate but helped to restore an organized cell monolayer. BEL cells stimulated to grow on ECM by treatment with EDGF exhibited at least transiently contact inhibition producing a perfectly organized epithelium similar to the one observed in vivo. These results suggest specific interactions between ECM or ECM components with BEL cell that restrain excessive cell spreading and restore an original polarized phenotype of the cells seen in vivo.

Animals↗
PubMed1983

Interaction of bovine epithelial lens (BEL) cells with extracellular matrix (ECM) and eye-derived growth factor (EDGF). II. Partial re-expression of the differentiated collagen distribution and phenotype.

The differentiated phenotype of bovine epithelial lens (BEL) cells consists primarily of type IV collagen production with homogeneous cellular form and monolayer organization. We have previously described how, after several subcultures, BEL cells lost this phenotype, which was replaced by a complex collagen mixture consisting predominantly of type I and type III collagens and a minor proportion of type IV collagen. The cells became irregular and formed multilayers. These dedifferentiated cells can re-express their initial morphological properties when subcultured on an extracellular matrix (ECM) in presence of an eye-derived growth factor (EDGF), as described in the first paper of this series [30]. Furthermore, those cells passaged only one time on ECM + EDGF partially re-express the native differentiated collagen phenotype. The cells synthesize a majority of type IV collagen (up to 65%) with minor amounts of interstitial collagens. As in early subcultured cells, the major proportion of total collagen accumulated in the cell layer. Taken together, the morphological and biochemical data emphasize the relationship between cell shape and collagen phenotype expression. They also provide a reversible system for the study of normal gene expression and pathological alterations.

Animals↗
PubMed1983

Interaction of bovine epithelial lens (BEL) cells with extracellular matrix (ECM) and eye-derived growth factor (EDGF). III. Control of glycoprotein and proteoglycan synthesis.

Bovine epithelial lens (BEL) cells, cultured in the presence or absence of an eye-derived growth factor (EDGF) on plastic surfaces or on extracellular matrix (ECM) laid down by corneal endothelial cells, were metabolically labelled with [3H] glucosamine and with [35S]O2+4. The newly formed glycoproteins and proteoglycans were determined and studied in the extracellular compartment. EDGF reduces radiosulfate incorporation and provides the formation of low molecular weight (LMW) proteoglycans and glycosaminoglycans. [3H]Glucosamine incorporation into the glycoprotein fractions is affected by EDGF and by ECM, but in a different manner. EDGF and ECM reduce the formation of the glycoproteins with an affinity towards the collagen, but the effect of EDGF and ECM on the other glycoproteins is different. It is suggested that the actions of EDGF and of ECM are at least partially different and mutually independent.

Animals↗
PubMed1983

State of differentiation of bovine epithelial lens cells in vitro. Relationship between the variation of the cell shape and the synthesis of crystallins.

Correlations between cell morphology and the expression of specific proteins (crystallins) have been investigated. Two different culture conditions have been chosen which keep bovine epithelial lens cells (BEL cells) in a monolayer of homogeneous epithelioid cells: (1) bovine retinal extract (EDGF) supplemented medium; (2) extracellular matrix (ECM) provided by corneal endothelial cells in standard medium has been compared to previous results obtained with BEL cells cultivated on plastic (Simonneau et al., 1983). Variations of the cell shape had no effect upon crystallin synthesis.

Animals↗
PubMed1983

Human and bovine vascular endothelial cells. Comparative effect on cell growth and longevity of an eye-derived growth factor (EDGF) and of extracellular matrix.

Human and bovine vascular endothelial cells from the umbilical vein and the aorta, respectively, were cultured in the presence of EDGF (a growth factor prepared from bovine retina) on plastic or on extracellular matrix (ECM). Both EDGF and ECM are required to allow the maximal proliferation of human cells and their organization in a typical monolayer. Conversely, bovine aortic endothelial cells grow perfectly in the absence of both factors in 6% fetal calf serum. However, a requirement for EDGF can also be demonstrated in low serum conditions, or in cells at high passage number. ECM had no growth promoting activity by itself. Thrombin acts similarly to EDGF on bovine serum-starved cells. EDGF prolongs the in vitro lifespan of both types of cells. Cells at all stages still synthesize factor VIII antigen as revealed by immunofluorescence. Thus EDGF, like other growth factors from brain, FGF or ECGF, may have an important role in angiogenesis, a critical problem in pathological retinas.

Animals↗
PubMed1982

Alterations in glycopeptide and glycosaminoglycan biosynthesis in bovine lens epithelial cells cultured in the presence of an eye-derived growth factor.

D-[3H]glucosamine-labeled glycosaminoglycans and glycopeptides, obtained by Pronase digestion from bovine lens epithelial cells grown in the presence and in the absence of an eye-derived growth factor, were investigated comparatively in the extra- and pericellular compartments of 16-17th subcultures. Glycosaminoglycans and glycopeptides were separated on Ultrogel AcA 202 column and the retained glycopeptides were further separated by the successive application of affinity, ion-exchange and exclusion chromatographic methods. The following results were obtained: (1) the proportion of the label increased in hyaluronic acid and decreased in the glycopeptide fraction on stimulation with the growth factor: (2) the comparison of the chromatographic elution profiles of the glycopeptides from control and stimulated cells revealed that differences between the two cell groups were largely quantitative. An increase in the high molecular weight glycopeptides, as it was found in transformed cells, could not be demonstrated in eye-derived growth factor-treated cells.

Animals↗
PubMed1982

Purification, characterization, and biological properties of the eye-derived growth factor from retina: analogies with brain-derived growth factor.

Several ocular tissues contain a polypeptide growth factor(s) (eye-derived growth factor(s) or EDGF) that stimulates the proliferation of a large variety of cells from different tissues or species. Partial purification of EDGF from adult bovine retina was accomplished by acid precipitation, blue Ultrogel chromatography, and high-pressure liquid chromatography. EDGF has an isoelectrical point at pH 4.5 +/- 0.5 and an apparent molecular weight of 17,500 +/- 3,500 measured by high-pressure liquid chromatography. On the basis of these data as well as its biological properties EDGF is different from other known growth factors. The specific activity of highly purified EDGF is 1,000-fold greater than that of a 20,000g supernatant of a crude retinal extract. At this stage of purification, EDGF stimulates replicative DNA synthesis and cell proliferation of bovine epithelium lens cells at a concentration of 14 ng/ml of culture medium and for these cells is as efficient as purified brain fibroblast growth factor. The same purification steps were applied to crude bovine brain extracts. Growth factor activity was recovered exactly as for EDGF with slightly smaller apparent molecular weight 14,000 +/- 3,500, suggesting a great similarity between the two tissues as a source of growth factors. A purification of about 2,500-fold was obtained and cell proliferation stimulated at a concentration of 100 ng/ml. Interestingly an inhibitory activity not retained on blue Ultrogel was recovered from both preparations.

Acetates↗
PubMed1981

Effects of retinal growth factor and of the increase of the number of subcultures on sulfated glycosaminoglycans of bovine lens epithelial cells.

Sulfated glycosaminoglycans of cultured bovine lens epithelial cells grown in the presence and in the absence of a retinal growth factor were investigated comparatively. The newly formed [35S]sulfate-labeled glycosaminoglycans were analysed in the extra-, peri- and intracellular compartments of early (4--5th) and late 17--18 h) subcultures. The following results were obtained: (1) Cultured lens epithelial cells grown in the presence or in the absence of the growth factor synthesize chondroitin 4- and 6-sulfates and dermatan sulfate, with heparan sulfate as the main component, the pericellular compartments were particularly rich in heparan sulfate; (2) The distribution pattern of the glycosaminoglycans changes during successive subcultures; the proportion of heparan sulfate increases in the pericellular compartment, the dermatan sulfate to chondroitin sulfate ratio increases in all three compartments; (3) IN contrast to the drastic decrease in the fibronectin levels in the presence of growth factor in the early subcultures, only minor differences were found between the glycosaminoglycan patterns of the treated and non-treated cells.

Animals↗
PubMed1981

Evolution of the distribution, proliferation and ultraviolet repair capacity of rat lens epithelial cells as a function of maturation and aging.

The symmetrical organization of lens epithelium was a determining factor in this study whose purpose was to investigate the growth of this tissue during development, maturation and aging. By direct observation it was possible to score all the nuclei, to determine four different zones of cellular density and to monitor them during the whole lifespan. The central zone is mainly quiescent and the proliferation at the periphery accounts for the low steady growth rate of the tissue. With aging there is a continuous decrease in the mitotic index and a cell size enlargement. These cells were able to perform unscheduled DNA synthesis in vitro after ultraviolet irradiation. There is an age-related decrease in DNA repair, but most of it occurs during development (until 59 weeks of age) and then remains constant (59-173 weeks). These results mean that in a differentiated pure cell population aging is not directly related to decline in unscheduled DNA synthesis.

Aging↗