Platelet-activating factor stimulation of p125(FAK) and p130(Cas) tyrosinephosphorylation in brain

The effect of platelet-activating factor (PAF) on protein tyrosine phosphor ylation was studied in rat brain slices. PAF induced a time and concentrati on-dependent increase in tyrosine phosphorylation of a doublet of approxima tely 125 kDa. These proteins were identified by immunoprecipitation as p125 (FAK) and pl30(Cas), using monoclonal antibodies. This effect was mediated by PAF receptors, as shown by its inhibition by the action of a PAF antagon ist. The tyrosine phosphorylation evoked by PAF was dependent, at least in part, on external calcium. The involvement of protein kinase C was demonstr ated by the synergistic effect of TPA on PAF-stimulated tyrosine phosphoryl ation. The finding that PAF stimulates tyrosine phosphorylation of both foc al adhesion protein p125(FAK) and p130(Cas) suggests that PAF might modulat e the integrin mediated signal transduction in the brain. (C) 1999 Elsevier Science B.V. Al rights reserved.