title: Gangliosides mediate association of tetanus toxin with neural cells in culture.
abstract: Somatic neurohybrid SB21B1 cells grown in serum exhibit limited capacity to bind 125I-labeled tetanus toxin and cannot synthesize gangliosides higher than GM2. By 6 h after supplementing the culture medium with pure or mixtures of brain gangliosides, binding of 125I-labeled tetanus toxin to cells increases approximately 8-fold compared to that of nonsupplemented cells. The uptake of added gangliosides is a saturable process and is facilitated by serum removal (2.1-fold) or substitution of growth factors for serum (3.8-fold). Enhancement of tetanus toxin binding to cells depends on the ganglioside species and concentration; GT1b (25 micrograms/ml) is, respectively, two and three times as effective as GD1b and GM1 in increasing toxin binding. Reconstitution of ganglioside-mediated tetanus toxin binding activity is a reversible phenomenon; removal of medium gangliosides causes a 3-fold drop in toxin binding by 24 h, after which an apparent plateau for at least 3 days above the basal level is established. As in cerebral cultures, binding of toxin to ganglioside-supplemented neurohybrid cells exhibits salt and sialidase sensitivity and is enhanced 2.6-fold at 37 degrees C compared to 0-4 degrees C. The resultant temperature-dependent toxin-cell association is sialidase insensitive. Fixation of cells by formaldehyde or treatment of ganglioside-supplemented cells with trypsin has no substantial effect on ganglioside-mediated binding of the toxin. Methanol/chloroform treatment of cells causes a 91.4% loss of binding activity.
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D005732:Gangliosides / Q000378:metabolism / Q000502:physiology*; D006822:Hybrid Cells; D007739:L Cells; D008565:Membrane Proteins; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D011950:Receptors, Cholinergic / Q000378:metabolism*; D013696:Temperature
chemical_list: D005732:Gangliosides; D008565:Membrane Proteins; D011950:Receptors, Cholinergic; C028728:tetanus toxin receptor