phosphatidylbutanol and Leukemia--Basophilic--Acute

Antigen (Ag)-stimulated phospholipase D (PLD) activation and secretion were almost abolished by pretreatment of rat basophilic leukemia (RBL)-2H3 cells for 4 h with 5 ng/ml Clostridium difficile Toxin B which is known to inhibit Rho family proteins (Rho, Cdc42, Rac). The concentration-dependent inhibition of PLD activation was well correlated with the level of glucosylation of Rho family proteins. In streptolysin O-permeabilized RBL cells, Toxin B suppressed [3H] phosphatidylbutanol (PBut) formation in response to guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) and phorbol 12-myristate 13-acetate (PMA) by 67 and 43%, respectively. The synergistic PLD activation by GTP gamma S and PMA was also reduced by Toxin B by 67%. These results suggest that the IgE receptor-coupled PLD activation is largely mediated by Rho proteins.

Topics: Animals; Bacterial Proteins; Bacterial Toxins; Cell Line; Cell Membrane Permeability; Clostridioides difficile; Cytotoxins; Dose-Response Relationship, Drug; Enzyme Activation; Glycerophospholipids; Guanosine 5'-O-(3-Thiotriphosphate); Kinetics; Leukemia, Basophilic, Acute; Phosphatidic Acids; Phospholipase D; Rats; Receptors, IgE; Signal Transduction; Streptolysins; Tetradecanoylphorbol Acetate; Tumor Cells, Cultured