| First Author | Moon SH | Year | 2012 |
| Journal | J Biol Chem | Volume | 287 |
| Issue | 18 | Pages | 14880-95 |
| PubMed ID | 22389508 | Mgi Jnum | J:184885 |
| Mgi Id | MGI:5426504 | Doi | 10.1074/jbc.M111.336776 |
| Citation | Moon SH, et al. (2012) Activation of mitochondrial calcium-independent phospholipase A2gamma (iPLA2gamma) by divalent cations mediating arachidonate release and production of downstream eicosanoids. J Biol Chem 287(18):14880-95 |
| abstractText | Calcium-independent phospholipase A(2)gamma (iPLA(2)gamma) (PNPLA8) is the predominant phospholipase activity in mammalian mitochondria. However, the chemical mechanisms that regulate its activity are unknown. Here, we utilize iPLA(2)gamma gain of function and loss of function genetic models to demonstrate the robust activation of iPLA(2)gamma in murine myocardial mitochondria by Ca(2+) or Mg(2+) ions. Calcium ion stimulated the production of 2-arachidonoyl-lysophosphatidylcholine (2-AA-LPC) from 1-palmitoyl-2-[(14)C]arachidonoyl-sn-glycero-3-phosphocholine during incubations with wild-type heart mitochondrial homogenates. Furthermore, incubation of mitochondrial homogenates from transgenic myocardium expressing iPLA(2)gamma resulted in 13- and 25-fold increases in the initial rate of radiolabeled 2-AA-LPC and arachidonic acid (AA) production, respectively, in the presence of calcium ion. Mass spectrometric analysis of the products of calcium-activated hydrolysis of endogenous mitochondrial phospholipids in transgenic iPLA(2)gamma mitochondria revealed the robust production of AA, 2-AA-LPC, and 2-docosahexaenoyl-LPC that was over 10-fold greater than wild-type mitochondria. The mechanism-based inhibitor (R)-(E)-6-(bromomethylene)-3-(1-naphthalenyl)-2H-tetrahydropyran-2-one (BEL) (iPLA(2)gamma selective), but not its enantiomer, (S)-BEL (iPLA(2)beta selective) or pyrrolidine (cytosolic PLA(2)alpha selective), markedly attenuated Ca(2+)-dependent fatty acid release and polyunsaturated LPC production. Moreover, Ca(2+)-induced iPLA(2)gamma activation was accompanied by the production of downstream eicosanoid metabolites that were nearly completely ablated by (R)-BEL or by genetic ablation of iPLA(2)gamma. Intriguingly, Ca(2+)-induced iPLA(2)gamma activation was completely inhibited by long-chain acyl-CoA (IC(50) approximately 20 mum) as well as by a nonhydrolyzable acyl-CoA thioether analog. Collectively, these results demonstrate that mitochondrial iPLA(2)gamma is activated by divalent cations and inhibited by acyl-CoA modulating the generation of biologically active metabolites that regulate mitochondrial bioenergetic and signaling functions. |
