Antibodies to ganglioside GM1 induce mitogenic stimulation and cap formation in rat thymocytes.
Antibodies towards the ganglioside GM1 [galactosyl-N-acetylgalactosaminyl-(N-acetylneuraminyl)-galactosyglucosyl ceramide] stimulated DNA synthesis in rat thymocytes. No mitogenic stimulation was observed  with the monomeric Fab fragment of anti-GM1, suggesting that cross-linking of the gangliosides or associated components was required for activation by these antibodies. Incubation of thymocytes with anti-GM1 and fluorescein-labeled anti-rabbit IgG at 0 degree C resulted in uniform ring-like or patchy staining that developed into a pronounced cap upon elevation of temperature. The cap had a characteristic uropod form, enriched with intracellular organelles. Sodium azide and cytochalasin B completely inhibited cap formation, while colchicine was without effect. These results imply a possible direct or indirect association between surface gangliosides and submembraneous cytoskeletal assemblies that control modulation of these surface components and may transmit stimuli to the interior of the cell.
D000818:Animals; D000906:Antibodies; D000918:Antibody Specificity; D002417:Cattle; D004247:DNA / Q000096:biosynthesis; D005455:Fluorescent Antibody Technique; D005732:Gangliosides / Q000276:immunology*; D007152:Immunologic Capping; D008297:Male; D008854:Microscopy, Electron; D008934:Mitogens; D051381:Rats; D013601:T-Lymphocytes / Q000276:immunology* / Q000378:metabolism / Q000648:ultrastructure
D000906:Antibodies; D005732:Gangliosides; D008934:Mitogens; D004247:DNA