The surface glycoproteins of human skin fibroblasts detected after electrophoresis by the binding of peanut (Arachis hypogaea) agglutinin and Ricinus communis (castor-bean) agglutinin I

A new methodology was developed to study the cell-surface glycoproteins of cultured human skin fibroblasts. This was based on the binding of a variety of biotinyl-lectins to nitrocellulose electrophoretic transfers of total fibroblast lysates after separation in sodium dodecyl sulphate/polyacrylamide gels, followed by reaction with avidin-biotinyl-peroxidase complexes and detection with 3,3'-diaminobenzidine. The technique proved to be very sensitive and a large number of glycoproteins were detected by binding of concanavalin A and wheat-germ agglutinin. Binding of peanut agglutinin and to a lesser extent of Ricinus communis agglutinin I were found to be dependent on prior removal of sialic acid residues from the glycoproteins. Since by treatment of intact viable cells with neuraminidase only external sialic acid residues were removed, peanut agglutinin and Ricinus communis agglutinin I could thus be utilized for selective detection of cell-surface glycoproteins. Also, because peanut agglutinin was known to bind preferentially to oligosaccharides of the O-glycosidic type, and Ricinus communis agglutinin I to those of the N-glycosidic type, the two lectins were complementary in displaying the surface glycoproteins and in providing information about their oligosaccharide composition.

Giant axonal neuropathy: an inborn error of organization of intermediate filaments

Light microscopic examination of cultured skin fibroblasts from three patients with giant axonal neuropathy (GAN) revealed large aggregates of intermediate filaments (IF). However, electrophoretic analysis of these cells showed normal amounts of vimentin, the fibroblast IF subunit protein. The isoelectric point and peptide mapping of vimentin were identical to controls. Moreover, vimentin was synthesized and phosphorylated at a normal rate. These findings demonstrate that GAN is an inborn error of the organization of IF and suggest that the basic genetic defect in GAN does not involve primarily the IF subunit proteins.

Giant axonal neuropathy: intermediate filament aggregates in cultured skin fibroblasts

Giant axonal neuropathy is characterized by large masses of filaments in neurons and other cells. Coomassie blue staining of the detergent-resistant cytoskeleton of cultured fibroblasts from three patients revealed cytoplasmic masses with the characteristics of aggregates of intermediate (8- to 10-nm) filaments. These fibroblast abnormalities provide definitive evidence for a genetic etiology of this disease and may be useful for prenatal diagnosis and for investigations of pathogenesis.

Lectin histochemistry of human skeletal muscle

Biotinyl derivatives of seven plant lectins-concanavalin A (Con A), peanut agglutinin (PNA), Ricinus communis agglutinin I (RCA I), Ulex europeus agglutinin I (UEA I), soybean agglutinin (SBA), Dolichos biflorus agglutinin (DBA), and wheat germ agglutinin (WGA)-were bound to cryostat sections of biopsied normal human muscle and visualized with avidin-horseradish peroxidase conjugates. A distinct staining pattern was observed with each lectin. The most general staining was observed with Con A, RCA I, and WGA, which permitted strong visualization of the plasmalemma-basement membrane unit, tubular profiles in the interior of muscle fibers, blood vessels, and connective tissue. PNA gave virtually no intracellular staining, while SBA and UEA I selectively stained blood vessels. DBA was unique in providing good visualization of myonuclei. In each case, lectin staining could be blocked by appropriate sugar inhibitors. Neuraminidase pretreatment of the cryostat sections altered the pattern of staining by all lectins except UEA I and Con A; staining with RCA I became stronger and that with WGA became less intense, while staining with PNA, SBA and DBA became stronger and more generalized, resembling that of RCA I. These effects of neuraminidase pretreatment are in conformity with the known structure of the oligosaccharide chains of membrane glycoproteins and specificities of the lectins involved.

Polypeptide heterogeneity of hamster and calf fibronectins

The adhesive glycoprotein fibronectin has been isolated from fresh hamster plasma by affinity chromatography on gelatin coupled to Sepharose beads by the method of Engvall & Ruoslahti [Int. J. Cancer (1979) 20, 1-5]. Polyacrylamide-gel electrophoresis of material heated in sodium dodecyl sulphate and 2-mercaptoethanol shows two prominent polypeptide subunits of approx. mol.wts. 215 000 and 200 000, with variable amounts of lower-molecular-weight fragments. The unexpected polypeptide heterogeneity of different preparations of hamster fibronectins and bovine serum fibronectin is shown to be partly an artefact and is generated during isolation and storage of purified fibronectin. Treatment of each hamster fibronectin subunit or a smaller fragment of approx. mol.wt. 140 000 with thermolysin or trypsin after radioiodination produces similar patterns of tyrpsine-containing peptides, indicating similar primary amino-acid sequences. Antibodies raised against the major subunits of hamster plasma fibronectin were coupled to Sepharose beads and used in conjunction with gelatin affinity chromatography to isolate fibronectins extracted with urea from baby-hamster kidney (BHK) cells and present in the long-term culture medium of these cells. The cell and medium fibronectins are similar to hamster plasma fibronectin in amino-acid and carbohydrate composition and also produce very similar peptide 'maps'. We conclude that the various forms of hamster fibronectins are structurally analogous in agreement with indistinguishable biological properties in mediating the substance adhesion of BKH cells [Pena & Hughes (1978) Cell Biol. Int. Rep. 3, 339-344].

A new technique for the visualization of the cytoskeleton in cultured fibroblasts with Coomassie blue R250

Staining of fibroblast monolayers with Coomassie brilliant blue R250 provides a relatively easy and fast method for visualization of cytoskeletal elements. Staining of detergent-extracted monolayers improves resolution and provides preparations comparable in definition to those obtained by specific immunofluorescence.

Two-dimensional electrophoresis of surface glycoproteins of normal BHK cells and ricin resistant mutants

The surface glycoproteins of baby hamster kidney (BHK) cells were iodinated by lactoperoxidase and submitted to a two-dimensional electrophoresis procedure involving isoelectric focusing in the first dimension and SDS gel electrophoresis in the second dimension. After autoradiography a complex but reproducible pattern was obtained. The technique was then applied to the study of three ricin-resistant mutant clones with reduced rates of cell-cell and/or cell-substratum adhesion. Abnormal patterns were observed in all three mutant clones indicating different mechanisms of ricin resistance and identifying glycoproteins which may be involved in cellular interactions.

Searching for molecular abnormalities in genetic diseases by the use of a double labeling technique. II. Deficiency of a basic protein in fibroblasts of patients with Pompe's disease

We used a double labeling technique to search for molecular defects in two fibroblast strains obtained from patients with Pompe's disease. Analysis of the double labeled subcellular fractions by sodium dodecyl sulfate (SDS) electrophoresis did not reveal any abnormalities except in the "mitochondrial-lysosomal" fraction. In this fraction ratio deviations indicated that in Pompe's disease there was a significant decrease in counts of a protein with molecular weight of about 29,000. After solubilization by freeze-thawing this protein was shown to have an isoelectric point of 7.9 in contrast to the alpha-glucosidase which focused at about pH 4.7. Two-stage gel studies demonstrated an estimated 90% reduction of this protein in Pompe's disease. Two-stage studies of acid alpha-glucosidase did not show any abnormal ratios of leucine incorporation. Similar although quantitatively less pronounced results were obtained in the study of skin fibroblasts from a patient with adult glycogen storage disease type II.

Searching for molecular abnormalities in genetic diseases by the use of a double labeling technique. I. Rationale, techniques, and initial evaluation

To meet the challenge of unravelling the molecular pathology of the ever expanding number of known genetic diseases in man, new efficient investigative techniques have to be designed. A procedure is presented for detection of protein defects in genetic diseases on the basis of structural rather than functional alterations. The technique is based on double labeling of normal and diseased fibroblast proteins followed by extensive fractionation and analysis. The rationale, advantages, and limitations of the procedure are discussed and the technical aspects of its use explained.

Fibroblast to substratum contacts mediated by the different forms of fibronectin

Highly purified preparations of fibronectin from bovine or hamster plasma and conditioned medium or urea extracts of BHK cells facilitate spreading of BHK cells to plastic surfaces. The different forms of fibronectin have very similar specific activities.

Biochemical investigations in cultured skin fibroblasts from patients with Duchenne muscular dystrophy

Cultured skin fibroblasts from patients with Duchenne muscular dystrophy were studied with a double-labeling procedure. Preliminary evaluation of the growth characteristics and average viability of dystrophic cells did not show any major abnormalities. Analysis of doubly labeled fibroblast mixture did not disclose any consistent anomaly in the distribution of subcellular fractions or in the major protein components of dystrophic fibroblasts.

Mitochondrial calcium overload: A general mechanism for cell-necrosis in muscle diseases

It is suggested that the mechanism of muscle-cell necrosis in various muscle diseases is explained by an increased net influx of calcium into cells which triggers a "vicious cycle" of mitochondrial calcium overloading and energy depletion. If correct, this hypothesis may offer the basis of a more rational treatment of some muscle diseases even before their primary aetiology is known.

Familial mental retardation in a family with an inherited chromosome rearrangement

A family of three generations has been described with an insertional type of chromosome rearrangement involving chromosomes 11 and 18[46,XX or XY, ins(11;18)(p15;q11q21)] detected by G-banding using a trypsin digestion method. Four members of this family with clinical features of 18q− have inherited the der(18) from their father and are thus deficient for (18)(q11q21). Three other family members have inherited the der(11) and thus have a duplication of the same segment [(18)(q11q21)]. Genetic marker studies on this family, show no significant segregation of any of the markers studied with either the der(11) or der(18). Eight family members had the PepA⁸PepA¹ genotype and four of these were carrying the der(18), indicating that the PepA locus which had been previously assigned to chromosome 18, does not lie in the segment q11→q21.