phosphatidylethanol and herbimycin

In tsRSV-infected NRK (tsNRK) cells, pp60(v-src) reactivation by temperature-shift from a nonpermissive temperature, 39 C, to a permissive one, 32 degrees C, induced the production of inositol phosphates (IPt) and phosphatidylethanol (PEt). This was accompanied by an increase in membrane-associated protein kinase C (PKC) activity in the absence of exogenous growth factors. However, with serum-stimulation, the amounts of IPt and PEt at 32 degrees C were less than those at 39 degrees C. Pretreatment with PKC inhibitors, Ro-31-8220 and staurosporine, enhanced the accumulation of IPt but not of PEt at 32 degrees C. The tyrosine phosphorylation of phospholipase Cgamma1 (PLCgamma1) was increased either by serum or by pp60(v-src) reactivation. These results suggest that serum transduces its signal through PLCgamma1 mediation, and that pp60(v-src), possibly through the PKC mediation, negatively affects serum-induced PLCgamma1 activation.

Topics: Animals; Benzoquinones; Cell Line, Transformed; Culture Media; Enzyme Inhibitors; Genes, src; Glycerophospholipids; Indoles; Inositol Phosphates; Isoenzymes; Kidney; Kinetics; Lactams, Macrocyclic; Oncogene Protein pp60(v-src); Phospholipase C gamma; Phosphotyrosine; Protein Kinase C; Quinones; Rats; Rifabutin; Staurosporine; Temperature; Type C Phospholipases

Herbimycin A, an inhibitor of protein tyrosine kinases, dose-dependently reduced PDGF-induced inositol phosphates (IPt) accumulation without effect on phosphatidylethanol (PEt) formation in PLC-gamma 1-overexpressing NIH 3T3 (NIH 3T3 gamma 1) cells. The compound also reduced tyrosine phosphorylations of some proteins including PLC-gamma 1 in response to PDGF. On the other hand, phorbol 12-myristate 13-acetate (PMA)-induced phospholipase D (PLD) activation was reduced by herbimycin A in the cells, indicating that the pathways for PLD activation by PDGF and PMA are different from each other. Also, these results suggest that PLC-gamma 1 activation is not always an upstream event for PLD activation and that tyrosine phosphorylation of one or more proteins not affected by herbimycin A should be indispensable for PLD activation in PDGF-stimulated NIH 3T3 gamma 1 cells.

Topics: 3T3 Cells; Animals; Benzoquinones; Enzyme Activation; Enzyme Inhibitors; Glycerophospholipids; Inositol Phosphates; Isoenzymes; Lactams, Macrocyclic; Mice; Phosphatidic Acids; Phospholipase C gamma; Phospholipase D; Phosphoproteins; Phosphorylation; Platelet-Derived Growth Factor; Protein-Tyrosine Kinases; Quinones; Rifabutin; Tetradecanoylphorbol Acetate; Type C Phospholipases; Tyrosine