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Biomedical subjects

E Engvall

Publications and source records attributed to E Engvall.

At least 109 records · Page 6Linked to original sources
PubMed1984

Basement membrane diversity detected by monoclonal antibodies.

Human fetal membranes or pepsin solubilized proteins thereof were used as immunogens in the production of monoclonal antibodies to basement membrane-associated components. Some of the antibodies obtained reacted with all basement membranes in indirect immunofluorescent microscopy, others reacted with all epithelial but not with endothelial basement membranes, and yet other antibodies reacted only with certain epithelial basement membranes in these tests. The reactivities of the antibodies demonstrate that different basement membranes are (immuno) chemically different and contain unique components in addition to ubiquitous components such as type IV collagen and laminin.

Animals↗
PubMed1983

Human laminin isolated in a nearly intact, biologically active form from placenta by limited proteolysis.

A protein with properties of laminin has been isolated from human placental extracts by using monoclonal antibodies. Placental tissue was extracted with 0.5 M NaCl and high molecular weight proteins were isolated from the extract by salt precipitation and gel filtration on Sepharose 6B. The resulting protein fraction which contained material cross-reactive with anti-sera to rat laminin was used as immunogen to prepare hybridomas. Thirteen hybrids produced antibodies which reacted with basement membrane-associated antigens in indirect immunofluorescence of tissues. One of these, 4E10, was characterized in detail. This monoclonal antibody reacted with human laminin as shown by several lines of evidence. Immunoprecipitation from metabolically labeled culture media of a human amniotic epithelial cell line with the 4E10 antibody followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed polypeptides with Mr similar to those of rat laminin. Immunochromatography of placental extracts obtained by limited pepsin digestion yielded material with main polypeptides at 160 and 130 kilodaltons in sodium dodecyl sulfate-polyacrylamide gel electrophoresis after reduction. These peptic fragments cross-reacted with rat laminin in immunodiffusion and enzyme immunoassay, and a polyclonal antiserum against the fragments reacted with basement membranes in tissues in a manner identical with the 4E10 antibody. Electron microscopic images of the human peptic fragments showed structures similar to the cross-shaped images of murine laminins, although the short arms were truncated to various degrees or even absent. The isolated peptic fragments also displayed biological activity similar to that of murine laminins in that the outgrowth of neurites by neuronal cells was promoted on plates coated with the fragments.

Antibodies, Monoclonal↗
PubMed1983

Sodium butyrate produces concordant expression of "early placental" alkaline phosphatase, pregnancy-specific beta 1-glycoprotein and human chronic gonadotropin beta-subunit in a newly established uterine cervical cancer cell line (SKG-IIIa).

The production of early and term placental alkaline phosphatase (ALP), human chorionic gonadotropin beta-subunit (beta-hCG) and pregnancy-specific beta 1-glycoprotein (SP1) was confirmed in the newly established uterine cervical cancer call line SKG-IIIa. Treatment of these cells in culture with sodium butyrate caused an increase of all of these oncodevelopmental proteins. On the other hand, prednisolone treatment enhanced only term placental ALP, while it reduced early placental ALP, beta-hCG and SP1. These data suggested that such oncotrophoblastic proteins as early placental ALP, beta-hCG and SP1 were concordantly modulated by butyrate and prednisolone. These findings may support the possibility of the reexpression of sets of development phase-specific genes in cancer cells.

Alkaline Phosphatase↗
PubMed1983

Laminin from rat yolk sac tumor: isolation, partial characterization, and comparison with mouse laminin.

Laminin was isolated from a rat yolk sac tumor by salt extraction, gel filtration, and affinity chromatography on heparin-Sepharose. The purified laminin gave two polypeptide chains with approximate Mr of 200,000 and 400,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Its amino acid composition and electron microscopic appearance were similar to those reported earlier for mouse laminin. Carbohydrate analysis revealed 13% carbohydrate consisting of N-acetylglucosamine, galactose, mannose, fucose, sialic acid, and small amounts of N-acetyl galactosamine. The purified rat laminin was immunologically very similar to mouse laminin as recognized by rabbit antibodies but was antigenically distinct when recognized by mouse antibodies.

Amino Acids↗
PubMed1983

Cell adhesive, protein binding, and antigenic properties of laminin.

The cell adhesive, protein-binding and immunological properties of laminin were studied. When present on a solid-phase, laminin promoted to some degree the adhesion of various types of cells including fibroblasts, but it was less active than insolubilized fibronectin, type I collagen, or type IV collagen. When laminin was present in solution, it promoted the adhesion of cells to surfaces that would otherwise be nonadhesive. No significant binding of laminin to type IV collagen could be demonstrated by affinity assays employing radioactively labeled ligands or enzyme-labeled antibodies. Binding of laminin to anti-laminin and to polyornithine could be readily demonstrated under the same conditions. The possible autoantigenicity of laminin was studied by immunizing mice with rat and mouse laminin. Rat laminin induced antibodies that reacted strongly with rat laminin and weakly with mouse laminin in enzyme immunoassay. Mouse laminin did not induce any detectable antibodies. These results confirm earlier work on cell adhesive properties of laminin but show that laminin is different from fibronectin adhesive properties of laminin but show that laminin is different from fibronectin in that laminin promotes adhesion of cells better when presented to the cells in a soluble form. They do not support the contention that laminin would bind directly to type IV collagen or that it would be autoantigenic.

Animals↗
PubMed1983

Laminin promotes neuritic regeneration from cultured peripheral and central neurons.

The ability of axons to grow through tissue in vivo during development or regeneration may be regulated by the availability of specific neurite-promoting macromolecules located within the extracellular matrix. We have used tissue culture methods to examine the relative ability of various extracellular matrix components to elicit neurite outgrowth from dissociated chick embryo parasympathetic (ciliary ganglion) neurons in serum-free monolayer culture. Purified laminin from both mouse and rat sources, as well as a partially purified polyornithine-binding neurite promoting factor (PNPF-1) from rat Schwannoma cells all stimulate neurite production from these neurons. Laminin and PNPF-1 are also potent stimulators of neurite growth from cultured neurons obtained from other peripheral as well as central neural tissues, specifically avian sympathetic and sensory ganglia and spinal cord, optic tectum, neural retina, and telencephalon, as well as from sensory ganglia of the neonatal mouse and hippocampal, septal, and striatal tissues of the fetal rat. A quantitative in vitro bioassay method using ciliary neurons was used to (a) measure and compare the specific neurite-promoting activities of these agents, (b) confirm that during the purification of laminin, the neurite-promoting activity co-purifies with the laminin protein, and (c) compare the influences of antilaminin antibodies on the neurite-promoting activity of laminin and PNPF-1. We conclude that laminin and PNPF-1 are distinct macromolecules capable of expressing their neurite-promoting activities even when presented in nanogram amounts. This neurite-promoting bioassay currently represents the most sensitive test for the biological activity of laminin.

Animals↗
PubMed1982

Nonhelical, fibronectin-binding basement-membrane collagen from endodermal cell culture.

A novel method of affinity chromatography on insolubilized collagen-binding fragments of fibronectin was utilized to isolate a random-coil collagenous protein from culture media of mouse teratocarcinoma-derived endodermal cells. These cells also produced another collagenous protein, which did not bind to fibronectin but could be isolated by differential salt precipitation. The affinity-purified collagen differs from its conventionally isolated counterpart in that it is not triple-helical in structure, its polypeptides are not disulfide-crosslinked and it has affinity for fibronectin in its native state. Both collagens resemble previously characterized type IV basement-membrane collagens with respect to their amino acid composition, cyanogen bromide peptides, chain size, immunological reactivity and tissue localization. The random-coil collagen is directly active in promoting the attachment of some lines of cells, but for attachment of the endodermal cells addition of fibronectin is required. This suggests that the presence of nonhelical, fibronectin-binding collagen may have biological significance in the interaction of cells with the extracellular matrix.

Amino Acids↗
PubMed1982

Cell attachment on replicas of SDS polyacrylamide gels reveals two adhesive plasma proteins.

A novel procedure that detects adhesive proteins in complex mixtures was used to characterize such proteins in plasma. The proteins are separated by SDS PAGE and transferred to nitrocellulose filters. Cells incubated on these filters attach to those proteins that have adhesive properties. When applied to human plasma proteins this procedure reveals, in addition to fibronectin, a cell-attachment protein with a polypeptide molecular weight of 70,000. Using a monoclonal antibody that inhibits attachment of cells to fibronectin, we show that this polypeptide is not a fragment of fibronectin and we present evidence that it is a component of the serum spreading factor. Therefore, as defined by our assay, this protein and fibronectin are the major attachment proteins for fibroblastic cells in plasma or serum.

Animals↗
PubMed1982

Molecular and biological interactions of fibronectin.

Fibronectin is a high molecular weight glycoprotein present at cell surfaces and in various body fluids. It is involved in cellular adhesion. The frequent absence of fibronectin from the surface of malignant cells may contribute to the invasive growth of tumors. To develop a better understanding of the functions of fibronectin, we have studied its structure by making use of proteolytic fragmentation and monoclonal antibodies. Fragments of plasma fibronectin which retain one or several of the affinities of intact fibronectin have been purified using affinity chromatography on collagen and heparin, and on monoclonal antibodies. These studies reveal a structure in which the different functions are located in separate protease-resistant molecular domains. The NH2-terminal domain contains the binding sites for fibrin, actin, and Staphylococci; this is followed by a collagen-binding domain, the cell attachment domain, and at the COOH-terminal end, the heparin-binding domain. These binding sites allow fibronectin to participate in multiple interactions with collagens and proteoglycans. The insoluble complexes formed by these 3 components that can be generated in vitro may represent a model for the basic structure of extracellular matrices. The role of fibronectin in such a matrix may be to contribute to the stability of the complex and to provide adhesion sites for cells. Disturbances in the interactions involving fibronectin could be potentially important to understanding diseases of connective tissues and in malignancy.

Animals↗
PubMed1982

Monoclonal antibodies in analysis of oncoplacental protein SP1 in vivo and in vitro.

Three monoclonal antibodies were developed to the placenta-specific glycoprotein SP1. The antibodies were used in the characterization of SP1 in placental tissue, pregnancy serum and urine, cancer serum, and cell culture. The three antibodies reacted similarly with purified SP1 of placental origin in radio- and enzyme immunoassay, and all three decorated the syncytiotrophoblast layer of placental villi in immunoperoxidase staining applied to fixed placental tissue. However, the three antibodies were found to have different and unique specificities and affinities. One antibody of relatively low affinity was used to isolate SP1 from placenta and fibroblast culture medium. The other two antibodies were used to develop a new and simple immunoassay for SP1. A panel of samples including cancer sera, pregnancy sera and urine, as well as cell culture fluids gave similar results in the monoclonal assay as in a conventional radioimmunoassay. Our work with monoclonal antibodies to SP1 provides further evidence for the production of authentic SP1 by fibroblastic cells in vitro and offers improved reagents for the isolation, characterization, and quantitation of an important marker of cancer and fetal development.

Antibodies, Monoclonal↗
PubMed1982

Production and characterization of a monoclonal antibody to human Type IV collagen.

We have produced a monoclonal antibody to human basement membrane Type IV collagen. The antibody reacts with the pepsin-resistant, collagenase-sensitive domain of Type IV collagen isolated from placental membranes, but not with human collagens of Types I, II, III, V, 1alpha, 2alpha, and 3alpha. The antibody precipitates biosynthetically labeled human Type IV procollagen, and the precipitate contains both the alpha1 (IV) and alpha2 (IV) chains, suggesting the occurrence of both of these chains within the same triple-helical molecule. When used in indirect immunofluorescence, the antibody gives brilliant staining of basement membranes from a variety of human tissues but does not stain tissues of bovine, canine, rabbit, rat, or mouse origin. It is suggested that this antibody will be of value in research on the structure of human basement membrane collagen, on the distribution of this collagen in various basement membranes, and particularly for the study of basement membranes in normal human development and pathologic processes.

Animals↗
PubMed1981

Alignment of biologically active domains in the fibronectin molecule.

Gelatin-binding material was isolated from a human plasma cryoprecipitate by affinity chromatography on gelatin-Sepharose. Individual fragments of fibronectin with Mr = 170,000, 100,000, and 80,000 and a mixture of fragments with Mr = 205,000 and 190,000 (200K fraction) were isolated from this material. These fragments reacted with antifibronectin and with antibodies to a gelatin-binding Mr = 70,000 tryptic fragment of fibronectin. They all shared the same NH2-terminal amino acid sequence. The 205K and 190K fragments bound also to heparin-Sepharose, whereas the smaller fragments did not. The 200K fraction and the 170K fragment mediated cell attachment when used to coat plastic, whereas the 100K and 80K fragments were inactive in this assay. Further digestion of the 205K and 190K fragments with chymotrypsin yielded separate sets of smaller fragments that bound to either gelatin-Sepharose or heparin-Sepharose, as well as fragments that did not show either of these binding activities but mediated cell attachment. Since the NH2-terminal ends of the 205K, 190K, 100K, and 80K fragments are the same, the results define the order of the active sites in the fibronectin molecule as gelatin-binding site, cell attachment site, and heparin-binding site.

Amino Acid Sequence↗
PubMed1981

Comparative studies on amniotic fluid and plasma fibronectins.

Human fibronectin was isolated from second-trimester amniotic fluid, from amniotic fluid obtained at term and from adult plasma. The amniotic-fluid fibronectins had a slightly higher apparent molecular weight on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis than the plasma fibronectin. Early- and late-amniotic-fluid fibronectin had 9.5 and 9.6% carbohydrate respectively, whereas plasma fibronectin had 5.8%. The amniotic-fluid fibronectins had similar mannose and sialic acid contents to plasma fibronectin, but greater amounts of glucosamine, galactosamine, galactose and fucose. There were no detectable differences in the amino-acid composition of amniotic-fluid and plasma fibronectins, and the patterns of peptides obtained after tryptic digestion of fibronectin from the two sources showed extensive similarities. Fibronectins from plasma and amniotic fluid were equally active in promoting cell attachment and were immunologically indistinguishable. These results show that fibronectin from amniotic fluid is more heavily glycosylated than plasma fibronectin or previously analysed fibronectins from cultured fibroblasts. The observed differences in glycosylation may be related to cell type and/or stage of development.

Amino Acids↗