Cytosolic phospholipase A(2) activity during the ongoing cell cycle

Cytosolic phospholipase A(2) (cPLA(2)) is of special interest because it se lectively releases arachidonic acid from membrane phospholipids. Arachidoni c acid has been implicated to play an important role in various cellular re sponses. Recently arachidonic acid release and prostaglandin synthesis have been shown to be cell cycle dependent and therefore the activity of cPLA(2 ) during the ongoing cell cycle was investigated, using the mitotic shake o ff method for cell synchronisation. cPLA(2) activity was high in mitotic ce lls and decreased rapidly in the early G1 phase. A strong increase in activ ity was measured following the G1/S transition in both neuroblastoma and Ch inese hamster ovary cells. The changes in activity were not due to a differ ence in cPLA(2) expression but due to phosphorylation of cPLA(2). Phosphory lation of cPLA(2) occurs through MAPK since the use of a specific MAPK kina se inhibitor and serum depletion of synchronised cells inhibited cPLA2 acti vity.