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M Aumailley

Publications and source records attributed to M Aumailley.

89 records · Page 5Linked to original sources
PubMed1986

Regulation of cell attachment and cell number by fibronectin and laminin.

We have examined the effect of laminin and fibronectin on the attachment and growth on type IV collagen of a line of mouse epithelial cells and a strain of adult human fibroblasts. Laminin stimulated attachment of the epidermal cells and fibronectin stimulated fibroblast attachment. At high concentrations (100 micrograms/ml), the attachment proteins altered the growth of cells in culture. The epidermal cells grew better in media containing fibronectin-free serum supplemented with laminin. Fibroblasts, on the other hand, grew best in media containing serum supplemented with fibronectin. These data suggest that laminin promotes epithelial cell growth whereas fibronectin promotes fibroblast growth. This observation was confirmed when these cells were cocultured in the presence of the attachment proteins or of their respective antibodies. The mouse epidermal cells grew best when laminin was added to cocultures of fibroblasts and epithelial cells. Fibroblasts grew best in the presence of antibody to laminin and poorly in the presence of antibody to fibronectin. Thus, fibronectin and laminin may participate in the regulation of cell populations in vivo and may be involved in epithelial-mesenchymal interactions.

Animals↗
PubMed1986

Defective attachment of dermatosparactic fibroblasts to collagens I and IV.

Attachment of fibroblasts from dermatosparactic sheep and cattle to collagenous substrates (types I and IV) is defective (30-50%) when compared with fibroblasts from normal or heterozygous animals. The difference was independent of the amount of substrate, incubation time and protein synthesis. No differences were observed in the binding to fibronectin or laminin. Reduced attachment to collagen can be partially restored by adding fibronectin. The polygonal morphology of dermatosparactic cells was, however, not altered by attachment and growth on dishes coated with different collagens or fibronectin. Reduced interaction with collagens could be due to changes in specific receptors and may represent a further pathological change in dermatosparactic animals.

Animals↗
PubMed1986

Attachment of cells to basement membrane collagen type IV.

Of ten different cell lines examined, three showed distinct attachment and spreading on collagen IV substrates, and neither attachment nor spreading was enhanced by adding soluble laminin or fibronectin. This reaction was not inhibited by cycloheximide or antibodies to laminin, indicating a direct attachment to collagen IV without the need of mediator proteins. Cell-binding sites were localized to the major triple-helical domain of collagen IV and required an intact triple helical conformation for activity. Fibronectin showed preferential binding to denatured collagen IV necessary to mediate cell binding to the substrate. Fibronectin binding sites of collagen IV were mapped to unfolded structures of the major triple-helical domain and show a similar specificity to fibronectin-binding sites of collagen I. The data extend previous observations on biologically potential binding sites located in the triple helix of basement membrane collagen IV.

Animals↗
PubMed1986

Spontaneous coronary artery dissection: case report and evidence for a defect in collagen metabolism.

Spontaneous coronary artery dissection is a rare disease with a higher prevalence in women, especially in the post-partum state. In one case, we attempted to relate this pathology to a disorder in collagen metabolism. A 32-year-old woman presented two episodes of myocardial infarction, 2 and 4 months after delivery which were shown to be due to two consecutive coronary artery dissections on coronary angiogram. Collagen metabolism was investigated in skin fibroblast cultures derived from the patient, and in control fibroblast cultures. After protein labelling in culture, total protein and collagen synthesis were determined. Quantification of procollagen synthesized in cell cultures and their rate of conversion into collagen were determined both in the culture media and a cell layer extract by DEAE cellulose chromatography. The results showed a reduced total collagen synthesis in the cultures of the patient in comparison with control cultures. The ratio between type I and III procollagen was not altered. The rate of conversion of procollagen into collagen was higher in the pathological cultures than in control cultures. Impaired collagen synthesis due perhaps to a change in hormonal equilibrium in the post-partum state might therefore have been responsible for coronary artery dissection.

Adult↗
PubMed1985

Biological activities of laminin.

Laminin is a multifunctional protein with diverse biological activities. Like fibronectin, it can influence cell adhesion, growth, morphology, differentiation, migration, and agglutination as well as the assembly of the extracellular matrix. Laminin primarily affects cells of epithelial origin, and the response varies depending on the cell. Because most differentiated cells are difficult to maintain in culture, laminin may be an important supplement in studies on cell differentiation in vitro.

Animals↗
PubMed1985

Structure and macromolecular organization of type VI collagen.

Collagen VI is a large, disulfide-bonded protein complex which is widely distributed in connective tissue. The constituent polypeptide chains (Mr = 110,000-140,000) consist of collagenous and noncollagenous segments, are degraded to chains of about half the size when collagen VI is solubilized by pepsin, and assemble to a unique pattern of oligomers. As revealed by electron microscopy, the triple-stranded protomer consists of a triple helix 105 nm in length flanked on each side by globular domains of similar size (diameter about 7 nm). Protomers are assembled to dimers by an antiparallel staggered alignment of triple-helical segments. This leads to inner regions, 75 nm in length, of two slightly supercoiled triple helices flanked by globular domains. At both sides 30-nm-long outer triple-helical segments emerge that are terminated by globules. Tetramers are formed from laterally aligned dimers that cross with their outer triple-helical segments in a scissors-like fashion. The same structures, except with much smaller globular domains, are found in pepsin-treated collagen VI. Disulfide-linked collagen VI produced by cultured fibroblasts has a size similar to that of genuine collagen VI found in tissue extracts. Larger forms of collagen VI are assembled from tetramers by end-to-end aggregation which because of an overlap of the outer segments brings all globular domains close together. This arrangement predicts microfibrillar structures in tissues with a periodicity of 100-110 nm and a diameter of 5-10 nm. Structures consistent with this proposal were indeed found by immunoelectron microscopy of placenta and aorta using the ferritin technique. Large, lateral aggregates of collagen VI microfibrils may in addition exist in cell cultures and tissues ("zebra collagen," "Luse bodies") and are presumably maintained by contacts between globular domains.

Animals↗
PubMed1984

Immunochemistry, genuine size and tissue localization of collagen VI.

Collagen VI was solubilized with pepsin from human placenta and used for preparing rabbit antisera. Major antigenic determinants were located in the central region of the antigen including triple-helical and globular structures. Antisera prepared against a constituent-chain showed preferential reactions with unfolded structures. Antibodies were purified by affinity chromatography and failed to cross-react with other collagen types I-V and with fibronectin. These antibodies demonstrated intracellular and extracellular collagen VI in fibroblast and smooth muscle cell cultures. Immunoblotting identified a disulfide-bonded constituent chain about twice as large as those of the pepsin fragments in both cell cultures and tissue extracts. Rotary shadowing electron microscopy indicated that the increase in mass is due to larger globular domains present at both ends of collagen VI monomers. Indirect immunofluorescence demonstrated a wide occurrence of collagen VI in connective tissue particularly of large vessels, kidney, skin, liver and muscle. Collagen VI is apparently not a typical constituent of cartilage or of basement membranes. Ultrastructural studies using the immunoferritin technique showed collagen VI along thin filaments or in amorphous regions of aortic media or placenta but not in association with thick, cross-striated collagen fibrils or elastin. This supports previous suggestions that collagen VI is a constituent of microfibrillar structures of the body.

Cells, Cultured↗
PubMed1984

Laminin, proteoglycan, nidogen and collagen IV: structural models and molecular interactions.

Major components of basement membranes, including collagen IV, laminin, heparan sulphate proteoglycan and nidogen, were isolated from the matrix of the EHS sarcoma. The purified components were analysed for their domain structure and for the participation of distinct domains in molecular interactions and cell binding. Collagen IV consists of four domains which have triple helical or non-collagenous structures. Self-assembly of the protein into a network-like organization occurs by specific interactions between N-terminal triple helical segments and between the C-terminal globules. Cell binding requires a central triple helical segment. Laminin has the shape of an asymmetrical cross; different globular domains within this structure mediate binding to proteoglycan and to cells. The proteoglycan consists of four heparan sulphate chains attached to a small protein core. These chains have the potential to bind laminin, fibronectin and collagen IV. Nidogen was isolated in several molecular forms which showed either self-aggregation or binding to laminin.

Animals↗
PubMed1982

Influence of cell density on collagen biosynthesis in fibroblast cultures.

Characteristic features of collagen metabolism in human skin fibroblasts were studied in relation to cell density. Measuring peptide-bound hydroxyproline we found that collagen synthesis per cell decreased when cultures approached confluency. On the other hand, the relative rate of collagen synthesis (collagen/total protein) was higher in quiescent than in proliferating cultures. With increasing cell density the proportion of type III collagen in comparison with type I was found to be slightly increased. In addition, in low-density cultures [alpha I(I)]3 collagen trimers were produced in considerable amounts, whereas they were no longer detected in cultures with a high cell density. Although hydroxylation of proline residues was normal in all cell stages, conversion of procollagen into collagen was found to depend strongly on the density at which the cells were investigated. Almost no cleavage of procollagen peptides was observed in rapidly growing cells, whereas highly confluent cell cultures converted most of the newly synthesized procollagen molecules.

Cell Count↗
PubMed1981

Case report and study of collagen metabolism in Marfan's syndrome.

The case report on a 33 year old woman with prominent features of Marfan's syndrome is presented. Characteristic signs were seen in the bones, the eyes, the cardiovascular system, and the lungs. Due to regurgitation of both the aortic and mitral valves and an aneurysm of the ascending aorta a double valve replacement was made, including a prosthesis of the aorta. The problems of early diagnosis and therapy of the life-threatening cardiovascular complications are discussed. Tissue specimens from the aorta were analysed histochemically and biochemically. Histology showed a typical necrosis of the media with cyst formation. Biochemical analysis by in vitro labeling of collagen in tissue explants and by electron microscopical evaluation showed proportions of type I and type III collagen which were significantly different from controls. In both the media and the adventitia the amount of type I collagen was drastically reduced as shown by quantitation of collagen and procollagen. Fibroblasts derived from the skin of the patient showed a normal content of type I and type III collagen. It is conceivable that the reduced content of type I collagen in the aortic wall is responsible for the weakness of the vessel wall causing formation of aneurysm and its sequelae.

Adult↗
PubMed1981

Collagen synthesis in organ culture of normal and atherosclerotic aortas.

Using pulse-label experiments in organ culture, collagen synthesis was studied in aortas from healthy and atherosclerotic specimens. Investigations were carried out on human atherosclerotic plaques as well as in the mini-pig in which atherosclerosis occurred spontaneously, and in the rabbit where atherosclerosis was experimentally induced by cholesterol-enriched feeding. When compared to total protein synthesis, the percentage of newly synthesized collagens measured as radioactive pepsin-resistant material, decreased with age in healthy specimens, whereas it remained at a higher level when the aortas were atherosclerotic. Subsequent molecular sieve chromatography of the radioactivity pepsin-resistant material allowed the separation type I collagen from type III collagen and their relative quantification. The results showed that the newly synthesized type III collagen accounted for 16-31% in aortic explants from young animals, for 30-36% when the explants were derived from older specimens and for 35-48% when the tissues were atherosclerotic.

Animals↗
PubMed1980

Biochemical and immunological studies of fibroblasts derived from a patient with Ehlers-Danlos syndrome type IV. Demonstrate reduced type III collagen synthesis.

Fibroblasts derived from a skin biopsy of a patient with the Ehlers-Danlos syndrome (EDS) type IV were cultured in monolayer. The amount of collagen synthesized during a 24-h pulse was not different from that found with normal fibroblasts. Chromatographic procedures and immunofluorescence staining showed a normal synthesis of type I procollagen and collagen but a deficiency in synthesis of type III procollagen and collagen. This could be corroborated by radioimmuno assays showing a reduction in type III procollagen by about 90%. The secretion and degradation of collagens was not altered. The results demonstrate that the molecular defect in this particular patient is due to an impairment of the mechanism controlling the gene expression for type III procollagen.

Cells, Cultured↗
PubMed1976

[Influence of a lathyric agent and of hypercholesterolemic serum on cell cultures of fetal rabbit aorta].

Cell cultures of foetal rabbit aorta are cultivated with a lathyric agent (beta-amino-propio-nitrile) or with an hypercholesterolemic serum; if morphological features, in these two cases, correspond with modifications observed, in vivo, when adult rabbits are respectively submitted to the same treatment, enzymatic activities of collagen metabolism vary in opposite way. Therefore, the influence of different parameters to be studied on vascular cell functions become easier.

Aminopropionitrile↗
PubMed1976

Galactosyl transferase assay. Application to experimental atherosclerosis.

To establish a repetitive measurement, aortic galactosyl transferase activity has been studied with a specific exogenous acceptor, collagen. Reactions were realized with an acellular biosynthesis mixture containing, collagen (3-4 mg/ml) an aliquot of enzymatic extract preparation (105000 g supernatant (2-3 mg/ml of proteins), UDP (14C) galactose (300 pM/ml). Galactose incorporation into collagen required Mn++ (2.5. 10-3M), incubation temperature of 37 degrees C and pH =7,75. Under such conditions a reproducible assay of aortic collagen galactosyl transferase was possible. After submitting rabbits to a chronic lathyric intoxication and/or to an hypercholesterolimic diet, galactosyl transferase activity was measured in rabbit aortic wall. Enzymatic activity was increased for rabbits under treatment, and the increase was directly proportional to the length of treatment (BAPN associated with cholesterolemic diet).

Aminopropionitrile↗
PubMed1975

[Enzyme alterations of the arterial wall following the combination of a lathyrogenic treatment and of moderate hypercholesterolemia in the young rabbit].

To determinate the part of humoural and parietal factors in atherosclerotic injury genesis, metabolism alteration study is realised on aortic cell wall of rabbits which are submitted to a chronical lathyritic intoxication alone, or simultaneously or alternatively associated with a cholesterolemic diet. Catabolic activity increase of beta-glucuronidase occurs in hypercholesterolemic rabbits. Beta-aminoproprionitrile, lathyrogenic drug used, stimulates biosynthetic pathways: increase of soluble proteins, energetic enzyme activities (lacticodeshydrogenase, malicodeshydrogenase), conjonctival protein metabolism (procollagen lysyl hydroxylase); in the same time, cell wall disturbances and lipidic deposits are facilitate when rabbits are submitted to cholesterolemic diet.

Aminopropionitrile↗