title: Sphingosine blocks both membrane fusion and calmodulin-dependent phosphorylation of the 100-kDa protein of chick embryonic myoblasts.
abstract: Sphingosine, a potent inhibitor of protein kinase C, was found to block membrane fusion of chick embryonic myoblasts in culture. This effect was dose-dependent and could be reversed upon removal of the drug. Treatment with 12-O-tetradecanoylphorbol 13-acetate, which is a powerful activator of protein kinase C and capable of preventing myoblast fusion, further potentiated the inhibitory effect of sphingosine. Thus, the sphingosine-mediated inhibition of myoblast fusion appears to be independent of protein kinase C. Sphingosine also decreased the phosphorylation state of the 100-kDa protein when given to the cell extracts, and this inhibition was competitive with calmodulin. Thus, sphingosine seems to act as a calmodulin antagonist. These results suggest that the sphingosine-mediated inhibition of myoblast fusion may be associated with the inhibitory effect of the drug against the calmodulin-dependent phosphorylation of the 100-kDa protein.
authors: Department of Molecular Biology and SRC for Cell Differentiation, College of Natural Sciences, Seoul National University, Korea.
authors: H S
authors: HS
authors: Kim
authors: I H
authors: IH
authors: Lee
authors: Y J
authors: YJ
authors: Jeon
authors: C H
authors: CH
authors: Chung
authors: D B
authors: DB
authors: Ha
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000502:physiology; D002642:Chick Embryo; D004533:Egtazic Acid / Q000494:pharmacology; D008561:Membrane Fusion / Q000187:drug effects*; D009124:Muscle Proteins / Q000378:metabolism*; D009132:Muscles / Q000166:cytology*; D010766:Phosphorylation / Q000187:drug effects; D013110:Sphingosine / Q000494:pharmacology*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D009124:Muscle Proteins; D014268:Trifluoperazine; D004533:Egtazic Acid; D013110:Sphingosine; D013755:Tetradecanoylphorbol Acetate