Crj. Kennedy et al., ROLE OF PLA(2), PLC, AND PLD IN BRADYKININ-INDUCED RELEASE OF ARACHIDONIC-ACID IN MDCK CELLS, American journal of physiology. Cell physiology, 40(4), 1996, pp. 1064-1072
The role of cytosolic phospholipase A(2) (cPLA(2)), phosphatidylcholin
e-specific phospholipase C (PC-PLC) and phospholipase D (PLD) in the b
radykinin (BK)-stimulated release of arachidonic acid (AA) was examine
d in Madin-Darby canine kidney (MDCK) cells. Release of AA, phosphoryl
choline, choline, and phosphatidic acid (PA) or the transphosphatidyla
tion product, phosphatidylethanol, was detected after 1 min of BK stim
ulation. A role for PC-PLC was confirmed with D609, which reduced BK-s
timulated AA by 70%. Ethanol (EtOH), which blunts PA formation, dimini
shed BK-stimulated AA release by 50%. Together, D609 and EtOH inhibite
d this release almost completely. Evidence indicated that diacylglycer
ol and PA can enhance PLA(2) activity when added to cytosol extracts.
The enzyme responsible for AA release was characterized as cPLA(2), si
nce PLA(2) activity assayed in cell extracts was largely inhibited by
an antibody to this enzyme. The membrane fraction PLA(2) activity incr
eased significantly in BK-stimulated cells. We conclude that BK signal
ing in MDCK cells is mediated by the lipid products of PC-PLC and PLD,
increasing cPLA(2) activity, possibly by causing perturbations in the
bilayer structure of its substrate, by a direct effect on the enzyme
or by activation of protein kinases such as protein kinase C.