Cellular arachidonate-releasing function of novel classes of secretory phospholipase A2s (groups III and XII).

Here we report cellular arachidonate (AA) release and prostaglandin (PG) production by novel classes of secretory phospholipase A(2)s (sPLA(2)s), groups III and XII. Human group III sPLA(2) promoted spontaneous AA release, which was augmented by interleukin-1, in HEK293 transfectants. The central sPLA(2) domain alone was sufficient for its in vitro enzymatic activity and for cellular AA release at the plasma membrane, whereas either the unique N- or C-terminal domain was required for heparanoid-dependent action on cells to augment AA release, cyclooxygenase-2 induction, and PG production.