Identification and Molecular Characterization of the CalB Domain of the Cytosolic Phospholipase A2 (cPLA2) in Human Neutrophils
The receptor-mediated activation of human neutrophils by ligands such as chemotactic peptide N-formyl-methionine-leucine-phenylalanine (fMLP) is coupled with the activation of phospholipases C and A2 (1,2). Phospholipase A2 (PLA2) hydrolyzes arachidonic acid (AA) and lysophospholipid from the sn-2 position of 1-alkyl-2-arachidonoyl-sn-3-glycerophosphocholine of the membrane (3). Currently, it is accepted that the cytosolic PLA2 (cPLA2) and not the secretory PLA2 (sPLA2) is primarily responsible for the release of AA (4) in most of the cell systems. The reasons for this assumption are based on the observations such as low requirements of Ca++ concentrations (micromolar for cPLA2 vs milimolar for sPLA2), fatty acid preference of cPLA2 at the sn-2 position (5), resistance of cPLA2 to disulfide-reducing agents (4) and increased concentrations of cytosolic Ca++ (5,6). In addition, it is stimulated by phosphorylation through protein kinase C (PKC), but inhibited by staurosporine, an inhibitor of PKC (7). Conversely, previous studies from our laboratory have shown that the inhibition of PKC by staurosporine potentiated the activation of PLC and PLA2 in fMLP-challenged human PMN (8–10).
KeywordsArachidonic Acid Human Neutrophil Arachidonic Acid Release U937 Cell Line Cytosolic Phospholipase
Unable to display preview. Download preview PDF.
- 2.Berridge, MJ (1987) Ann. Rev. Biochem., 56, 159–193.Google Scholar
- 3.Hanahan, DJ (1986) Ann. Rev. Biochem., 55, 483–509.Google Scholar
- 8.Nigam et al. (1992) Biochim. Biophys. Acta, 1135, 301–308.Google Scholar
- 10.Nigam, S. et al. (1995) Adv. Prostagl. Thr. Leukotr. Res., 23, 471–475.Google Scholar
- 12.Sharp, JD et al. (1991) J. Biol. Chem., 266, 14850–14853Google Scholar