A heparin-sensitive phospholipase A(2) and prostaglandin endoperoxide synthase-2 are functionally linked in the delayed phase of prostaglandin D-2 generation in mouse bone marrow-derived mast cells

BALB/cJ mouse bone marrow-derived mast cells (BMMC) developed with interleukin (IL)-3 can be stimulated by c-kit ligand (KL) in the presence of IL-10 and IL-1 beta for sequential immediate and delayed generation of prostaglandin (PG) D-2 through utilization of constitutive prostaglandin endoperoxide synthase (PGHS) -1 and induced PGHS-2, respectively (Murakami, M., Matsumoto, R., Austen, K, F., and Arm, J. P. (1994) J. Biol, Chem, 269, 22269-22275), We now report that BALB/cJ BMMC stimulated with KL + IL-10 + IL-1 beta also exhibit the biphasic release of [H-3]arachidonic acid with an immediate phase over the first 10 min followed by a delayed phase from 2 to 7 h, The delayed phase of arachidonic acid release and of PGD(2) generation was inhibited by heparin, which concomitantly released a phospholipase (PL) A(2) from the cells into the supernatant. Both dexamethasone and a type II PLA(2) inhibitor, 12-epi-scalaradial, suppressed delayed-phase PGD(2) generation at concentrations that did not affect immediate eicosanoid generation, Transcripts for type IIA PLA(2), as assessed by reverse transcription-polymerase chain reaction, were progressively induced in BALB/cJ BMMC treated for 2 to 7 h with KL + IL-10 + IL-1 beta; the induction of these transcripts was down-regulated by 10(-6) M dexa methasone. The expression of steady-state transcripts and protein for cytosolic PLA(2) (cPLA(2)) did not change, PGHS-2-dependent delayed-phase PGD(2) generation elicited by IgE-dependent activation of BALB/cJ BMMC primed with KL + IL-10 was also accompanied by the induction of type IIA PLA(2) transcripts and was suppressed by heparin, with concomitant release of PLA(2) into the supernatant, However, both the direct, cytokine stimulated and the cytokine primed, IgE-dependent, delayed phase PGD(2) generation occurred in BMMC from C57BL/6J mice, which have a natural disruption of the type IIA PLA(2) gene. Thus, kinetic, pharmacologic, and genetic analyses suggest that an inducible, heparin-sensitive PLA(2), rather than cPLA(2), provides arachidonic acid to concomitantly induced PGHS-2 for delayed phase PGD(2) biosynthesis in activated BMMC, Further more, this heparin-sensitive PLA(2) likely represents a novel PLA(2) or a new function for a known low molecular weight PLA(2).