cytochalasin-d and phosphatidylinositol-4-phosphate

The mechanism whereby agonist occupancy of muscarinic cholinergic receptors elicits an increased tyrosine phosphorylation of focal adhesion kinase (FAK) and paxillin has been examined. Addition of oxotremorine-M to SH-SY5Y neuroblastoma cells resulted in rapid increases in the phosphorylation of FAK (t(1/2) = 2 min) and paxillin that were independent of integrin-extracellular matrix interactions, cell attachment, and the production of phosphoinositide-derived second messengers. In contrast, the increased tyrosine phosphorylations of FAK and paxillin were inhibited by inclusion of either cytochalasin D or mevastatin, agents that disrupt the cytoskeleton. Furthermore, phosphorylation of FAK and paxillin could be prevented by addition of either wortmannin or LY-294002, under conditions in which the synthesis of phosphatidylinositol 4-phosphate was markedly attenuated. These results indicate that muscarinic receptor-mediated increases in the tyrosine phosphorylation of FAK and paxillin in SH-SY5Y neuroblastoma cells depend on both the maintenance of an actin cytoskeleton and the ability of these cells to synthesize phosphoinositides.

Topics: Actins; Androstadienes; Cell Adhesion; Cell Adhesion Molecules; Chromones; Cytochalasin D; Cytoskeletal Proteins; Cytoskeleton; Enzyme Inhibitors; Focal Adhesion Kinase 1; Focal Adhesion Protein-Tyrosine Kinases; GTP-Binding Proteins; Humans; Lovastatin; Morpholines; Muscarinic Agonists; Neuroblastoma; Nucleic Acid Synthesis Inhibitors; Paxillin; Phosphatidylinositol Phosphates; Phosphatidylinositols; Phosphoproteins; Phosphorus Radioisotopes; Phosphorylation; Protein-Tyrosine Kinases; Receptor, Insulin; Receptors, Muscarinic; Second Messenger Systems; Tumor Cells, Cultured; Tyrosine; Wortmannin