Ganglioside GD3 monoclonal antibody-induced paxillin tyrosine phosphorylation and filamentous actin assembly in cerebellar growth cones

We have demonstrated that antibody to ganglioside GD3 (R24) immunoprecipitates src-family tyrosine kinase Lyn from primary cerebellar granule cells and R24 treatment of the intact cells induces Lyn activation and rapid tyrosine phosphorylation of several substrates, suggesting the functional association of ganglioside GD3 with Lyn. In this study, R24 treatment of primary cerebellar granule cells enhances phosphorylation of paxillin at tyrosine residue 118 and induces filamentous actin assembly and neurite outgrowth. R24 treatment of cerebellar growth cone membrane fraction induces prominent tyrosine phosphorylation of 68 kDa protein which comigrates with phosphopaxillin at tyrosine residue 118. Tyrosine phosphorylation of paxillin is known to regulate actin cytoskeleton-dependent changes in cell morphology. Signal transduction by ganglioside GD3 is involved in growth cone morphology via tyrosine phosphorylation of paxillin.