Function, activity, and membrane targeting of cytosolic phospholipase A(2)zeta in mouse lung fibroblasts.
Group IVA cytosolic phospholipase A(2) (cPLA(2)alpha) initiates eicosanoid production; however, this pathway is not completely ablated in cPLA(2)alpha(-/-) lung fibroblasts stimulated with A23187 or serum. cPLA(2)alpha(+/+) fibroblasts preferentially released arachidonic acid, but A23187-stimulated cPLA(2)alpha(-/-) fibroblasts nonspecifically released multiple fatty acids. Arachidonic acid release from cPLA(2) alpha(-/-) fibroblasts was inhibited by the cPLA(2)alpha inhibitors pyrrolidine-2 (IC(50), 0.03 microM) and Wyeth-1 (IC(50), 0.1 microM), implicating another C2 domain-containing group IV PLA(2). cPLA(2) alpha(-/-) fibroblasts contain cPLA(2)beta and cPLA(2)zeta but not cPLA(2)epsilon or cPLA(2)delta. Purified cPLA(2)zeta exhibited much higher lysophospholipase and PLA(2) activity than cPLA(2)beta and was potently inhibited by pyrrolidine-2 and Wyeth-1, which did not inhibit cPLA(2)beta. In contrast to cPLA(2)beta, cPLA(2)zeta expressed in Sf9 cells mediated A23187-induced arachidonic acid release, which was inhibited by pyrrolidine-2 and Wyeth-1. cPLA(2)zeta exhibits specific activity, inhibitor sensitivity, and low micromolar calcium dependence similar to cPLA(2)alpha and has been identified as the PLA(2) responsible for calcium-induced fatty acid release and prostaglandin E(2) production from cPLA(2) alpha(-/-) lung fibroblasts. In response to ionomycin, EGFP-cPLA(2)zeta translocated to ruffles and dynamic vesicular structures, whereas EGFP-cPLA(2)alpha translocated to the Golgi and endoplasmic reticulum, suggesting distinct mechanisms of regulation for the two enzymes.
Ghosh
Moumita
M
Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research Center, Denver, Colorado 80206, USA.
Loper
Robyn
R
Ghomashchi
Farideh
F
Tucker
Dawn E
DE
Bonventre
Joseph V
JV
Gelb
Michael H
MH
Leslie
Christina C
CC
D000595:Amino Acid Sequence; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D054513:Group IV Phospholipases A2; D007313:Insecta; D008168:Lung / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D054801:Phosphoinositide Phospholipase C; D010741:Phospholipases A / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D010738:Type C Phospholipases / Q000378:metabolism / Q000502:physiology*
D016718:Arachidonic Acid; D010741:Phospholipases A; D054513:Group IV Phospholipases A2; C519835:Pla2g4f protein, mouse; D010738:Type C Phospholipases; D054801:Phosphoinositide Phospholipase C; C499234:Plcz1 protein, mouse