A HEPARIN-SENSITIVE PHOSPHOLIPASE A(2) AND PROSTAGLANDIN ENDOPEROXIDESYNTHASE-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 int erleukin (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 generatio n of prostaglandin (PG) D-2 through utilization of constitutive prosta glandin endoperoxide synthase (PGHS) -1 and induced PGHS-2, respective ly (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 stim ulated with KL + IL-10 + IL-1 beta also exhibit the biphasic release o f [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 arachi donic 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) inhibito r, 12-epi-scalaradial, suppressed delayed-phase PGD(2) generation at c oncentrations that did not affect immediate eicosanoid generation, Tra nscripts for type IIA PLA(2), as assessed by reverse transcription-pol ymerase chain reaction, were progressively induced in BALB/cJ BMMC tre ated 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 express ion 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) transcr ipts and was suppressed by heparin, with concomitant release of PLA(2) into the supernatant, However, both the direct, cytokine stimulated a nd 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 mor e, this heparin-sensitive PLA(2) likely represents a novel PLA(2) or a new function for a known low molecular weight PLA(2).