Functional crosstalk between phospholipase D₂ and signaling phospholipase A₂/cyclooxygenase‐2‐mediated prostaglandin biosynthetic pathways

Abstract

We performed reconstitution analyses of functional interaction between phospholipase A 2 (PLA 2 ) and phospholipase D (PLD) enzymes. Cotransfection of HEK293 cells with cytosolic (cPLA 2 ) or type IIA secretory (sPLA 2 -IIA) PLA 2 and PLD 2 , but not PLD 1 , led to marked augmentation of stimulus-induced arachidonate release. Interleukin-1-stimulated arachidonate release was accompanied by prostaglandin E 2 production via cyclooxygenase-2, the expression of which was augmented by PLD 2 . Conversely, activation of PLD 2 , not PLD 1 , was facilitated by cPLA 2 or sPLA 2 -IIA. Thus, our results revealed functional crosstalk between signaling PLA 2 s and PLD 2 in the regulation of various cellular responses in which these enzymes have been implicated. ß

20-Hydroxyeicosatetraenoic Acid Mediates Angiotensin II–Induced Phospholipase D Activation in Vascular Smooth Muscle Cells

“…It has been reported that the activation of PLD depends on cPLA 2 in rat heart sarcolemma, 13 leukocytes, 14 and HEK293 cells. 15 Supporting this hypothesis was our demonstration that the PLA 2 inhibitor MAFP 21 and cPLA 2 antisense blocked Ang II-induced PLD activation in rabbit VSMCs. Although MAFP inhibits both cPLA 2 and iPLA 2 , our data with cPLA 2 antisense oligonucleotides and the lack of inhibition of Ang II-induced PLD activation by iPLA 2 inhibitor HELSS 22 suggest that cPLA 2 mediates Ang II-induced PLD activation.…”

“…To assess the contribution of PLD to arachidonic acid release for prostaglandin synthesis in rabbit VSMCs, we examined the effects of inhibitors of PLD (C 2 ceramide), phosphatidate phosphohydrolase (propranolol), and diacylglycerol lipase (RHC-80267) 15 on Ang II-induced arachidonic acid release. PLD activity was reduced by C 2 ceramide (10 mol/L for 4 hours) but not by C 2 dihydroceramide, an inactive analog of C 2 ceramide (Figure 2A).…”

“…15 To assess the contribution of cPLA 2 to Ang II-induced PLD activation, we used MAFP (50 mol/L), 21 a PLA 2 inhibitor, and HELSS (haloenol lactone suicide substrate), a selective calcium-independent PLA 2 (iPLA 2 ) inhibitor with a 1000-fold selectivity for iPLA 2 over cPLA 2 at 10 mol/L. 22 As shown in Figure 3, Ang II-induced PLD activity was inhibited by MAFP but not by HELSS in VSMCs.…”

“…11 Ang II also activates ras/MAP kinase via arachidonic acid metabolites formed through CYP4A and lipoxygenase . 12 These observations, together with recent reports that the PLD activation in cardiac sarcolemma, 13 leukocytes, 14 and HEK 293 cells 15 is mediated through the stimulation of cPLA 2 , raised the possibility that the activation of PLD in VSMCs by Ang II might be mediated by the ras/MAP kinase pathway metabolites of arachidonic acid that are generated by the initial activation of cPLA 2 . To test this hypothesis, we examined the effect of various inhibitors of this pathway on Ang II-induced PLD activation in rabbit VSMCs.…”

Regulation of Cyclooxygenase-2 Expression by Phospholipase D in Human Amnion-Derived WISH Cells

“…The relative contribution of these factors to PLD activation is highly dependent on the cell type and signaling model examined. Several lines of evidence have suggested a functional role for PLD in COX-2 regulation during cell activation (Sciorra and Daniel, 1996;Kaneki et al, 1998;Ueno et al, 2000). However, the contribution of PLD to COX-2 expression and PG production has not been as extensively studied.…”