Protein kinase C activators of the teleocidin family decrease the IgE-binding capacity of rat basophilic leukemia cells.
The tumor promoters 12-O-tetradecanoylphorbol-13-acetate (TPA) and the teleocidins (TCDs) had similar inhibitory effects on IgE binding onto the membrane of rat basophilic leukemia (RBL)-2H3 cells. The level of expression of the functional IgE Fc receptor (Fc epsilon R), as measured by CELISA, was decreased up to a maximum of 60% within 5 min-1 h of treatment. This inhibition was obtained at concentrations of 0.1 microgram/ml for most TCDs, of 1 microgram/ml for TPA and of 20 micrograms/ml for one TCD (olivoretin A). These molecules also decreased the amount of cell-bound IgE detectable by CELISA on cells that had been coated with IgE prior to TCD treatment. When incubated with RBL-2H3 cells for 30 min-2 h, the TCDs and TPA stimulated serotonin release. Depending on their concentration, they had various effects on IgE-plus antigen-induced serotonin release. It is suggested that the down-regulation of IgE receptor expression by these tumor promoters is mediated through protein kinase C activation and phosphorylation of the Fc epsilon R.
D000818:Animals; D001491:Basophils; D002455:Cell Division; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D007073:Immunoglobulin E / Q000378:metabolism*; D007942:Leukemia, Experimental / Q000473:pathology*; D008235:Lyngbya Toxins / Q000494:pharmacology*; D011485:Protein Binding; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D011961:Receptors, Fc / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D014407:Tumor Cells, Cultured / Q000187:drug effects
D008235:Lyngbya Toxins; D011961:Receptors, Fc; C022176:teleocidins; D012701:Serotonin; D007073:Immunoglobulin E; D011493:Protein Kinase C