pp60(v-src) reactivation inhibits serum-induced accumulation of inositol phosphates and phosphatidylethanol in tsNRK

In tsRSV-infected NRK (tsNRK) cells, pp60(v-src) reactivation bytemperature -shift from a nonpermissive temperature, 39 degrees C, to a permissive one, 32 degrees C, induced the production of inositol phosphates (IPt) and phos phatidylethanol (PEt), This was accompanied by an increase in membrane-asso ciated protein kinase C (PKC) activity in the absence of exogenous growth f actors. However, with serum-stimulation, the amounts of IPt and PEt at 32 d egrees C were less than those at 39 degrees C, Pretreatment with PKC inhibi tors, Re-31-8220 and staurosporine, enhanced the accumulation of IPt but no t of PEt at 32 degrees C. The tyrosine phosphorylation of phospholipase C g amma 1 (PLC gamma 1) was increased either by serum or by pp60(v-src) reacti vation. These results suggest that serum transduces its signal through PLC gamma 1 mediation, and that pp60(v-src), possibly through the PKC mediation , negatively affects serum-induced PLC gamma 1 activation.