P. Dieter et E. Fitzke, DIFFERENTIAL REGULATION OF PHOSPHOLIPASE-D AND PHOSPHOLIPASE-C BY PROTEIN-KINASE-C-BETA AND PROTEIN-KINASE-C-DELTA IN LIVER MACROPHAGES, Cellular signalling, 7(7), 1995, pp. 687-694
We have studied activation of phospholipase (PL) C and PLD in liver ma
crophages labelled with [H-3]arachidonic acid. Zymosan, phorbol 12-myr
istate 13-acetate (PMA), A23187 and fluoride but not arachidonic acid
or lipopolysaccharide (LPS) induce an activation of PLD ([H-3]phosphat
idylethanol (PEt) accumulation). An activation of PLC ([3H]diacylglyce
rol (DAG) accumulation) is measured with zymosan, PMA and fluoride but
not with A23187, LPS or arachidonic acid whereas inositol phosphates
are formed with zymosan, only. Removal of extracellular calcium reduce
s the formation of [H-3]PEt and [H-3]DAG while pretreatment of the cel
ls with dexamethasone reduces [H-3]PEt formation, only. PMA- and zymos
an-induced activation of PLD and PMA-induced activation of PLC both se
em to be mediated by protein kinase (PK) C-beta whereas zymosan-induce
d activation of PLC is negatively controlled by PKC-delta. We could fu
rthermore present evidence that the release of [H-3]arachidonic acid i
n these cells occurs independent of an activation of PLD.