RESUMO
Both Fas and PMA can activate phospholipase D via activation of protein kinase Cbeta in A20 cells. Phospholipase D activity was increased 4 fold in the presence of Fas and 2.5 fold in the presence of PMA. The possible involvement of tyrosine phosphorylation in Fas-induced activation of phospholipase D was investigated. In five minute after Fas cross-linking, there was a prominent increase in tyrosine phosphorylated proteins, and it was completely inhibited by D609, a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). A tyrosine kinase inhibitor, genistein, can partially inhibit Fas-induced phospholipase D activation. There were no effects of genistein on Fas-induced activation of PC-PLC and protein kinase C. These results strongly indicate that tyrosine phosphorylation may in part account for the increase in phospholipase D activity by Fas cross-linking and D609 can block not only PC-PLC activity but also tyrosine phosphorylation involved in Fas-induced phospholipase D activation.
Assuntos
Camundongos , Animais , Anticorpos Monoclonais/imunologia , Receptor fas/imunologia , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Linhagem Celular , Reagentes de Ligações Cruzadas , Relação Dose-Resposta Imunológica , Ativação Enzimática , Genisteína/farmacologia , Hidrólise , Linfoma/patologia , Fosfolipases Tipo C/antagonistas & inibidores , Fosfolipase D/metabolismo , Fosforilação , Fosforilcolina/metabolismo , Solubilidade , Tionas/farmacologia , Células Tumorais Cultivadas , Tirosina/metabolismo , Água/químicaRESUMO
Both Fas and PMA can activate phospholipase D via activation of protein kinase Cbeta in A20 cells. Phospholipase D activity was increased 4 fold in the presence of Fas and 2.5 fold in the presence of PMA. The possible involvement of tyrosine phosphorylation in Fas-induced activation of phospholipase D was investigated. In five minute after Fas cross-linking, there was a prominent increase in tyrosine phosphorylated proteins, and it was completely inhibited by D609, a specific inhibitor of phosphatidylcholine-specific phospholipase C (PC-PLC). A tyrosine kinase inhibitor, genistein, can partially inhibit Fas-induced phospholipase D activation. There were no effects of genistein on Fas-induced activation of PC-PLC and protein kinase C. These results strongly indicate that tyrosine phosphorylation may in part account for the increase in phospholipase D activity by Fas cross-linking and D609 can block not only PC-PLC activity but also tyrosine phosphorylation involved in Fas-induced phospholipase D activation.
