The new basement membrane antigen recognized by the monoclonal antibody GB3 is a large size glycoprotein: modulation of its expression by retinoic acid.
Further biochemical investigations on the hemidesmosome-associated epidermal basement membrane component recognized by the monoclonal antibody GB3 are presented in this study. We previously found that the expression of this constituent is impaired in a severe genodermatosis termed lethal junctional epidermolysis bullosa. We demonstrate now that this factor is a very large glycoprotein (apparent molecular weight, 600 kDa) made up of polypeptides in the range of 93.5 to 150 kDa, and containing N-linked oligosaccharide chains. Both endo-beta-N-acetylglucosaminidases and neuraminidase hydrolysis, as well as concanavalin A binding experiments were performed on the GB3 radioimmunoprecipitated polypeptides from cultured human keratinocytes. They showed that the antigen subunits probably bear both 'high-mannose' and 'complex' type glycosidic chains. The chronic exposure of cultured human keratinocytes to retinoic acid (10(-8) to 10(-6) M) resulted in no apparent changes in the overall bulk of these glycosidic chains, but a dose-dependent increase of synthesis and secretion of the antigen was observed. A relative induction factor of 4 was obtained in cultures treated with 10(-6) M retinoic acid. This induction was also observed morphologically by indirect immunofluorescence at the basement membrane zone from cultured human keratinocytes grown on dead de-epidermized dermis. These results further emphasize the influence of glycoproteins in cell-cell and cell-substratum attachment. Furthermore, the ability to modulate this antigen may be relevant for the understanding of the molecular defect involved in lethal junctional epidermolysis bullosa.
Verrando
P
P
Laboratoire de Recherches Dermatologiques, UER Médecine, Nice, France.
Pisani
A
A
Ortonne
J P
JP
D000911:Antibodies, Monoclonal / Q000276:immunology; D001485:Basement Membrane / Q000276:immunology*; D002478:Cells, Cultured; D003208:Concanavalin A / Q000378:metabolism; D003896:Desmosomes / Q000276:immunology*; D000939:Epitopes; D005455:Fluorescent Antibody Technique; D006026:Glycoside Hydrolases / Q000378:metabolism; D006801:Humans; D007158:Immunologic Techniques; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins / Q000276:immunology*; D008970:Molecular Weight; D010084:Oxidation-Reduction; D014212:Tretinoin / Q000494:pharmacology*; D014415:Tunicamycin / Q000494:pharmacology
D000911:Antibodies, Monoclonal; D000939:Epitopes; D046911:Macromolecular Substances; D008562:Membrane Glycoproteins; D003208:Concanavalin A; D014415:Tunicamycin; D014212:Tretinoin; D006026:Glycoside Hydrolases