Overview

Lipid Second Messengers and Phospholipases

Characterization of Phospholipase A2

Our goal is to identify and characterize in vitro all of the individual phospholipases involved in a given cell’s regulation and to also characterize that regulation in the intact cell and tissue. To that end, our laboratory has focused initially on phospholipase A2 [Review: 1] where we obtained three distinct types of PLA in pure form and studied their in vitro activities. This includes several Ca2+-dependent secretory enzymes (sPLA2), the Ca2+-dependent cytosolic enzyme (cPLA2) and a Ca2+-independent PLA2 (iPLA2) [Review: 2] which we were the first to identify, purify and characterize (3) and study its inhibition (4). This Group VI enzyme has been cloned (5). We were the first to find that the Group V sPLA2 is expressed and secreted in response to stimuli (6) and we have identified critical residues in the Group IV cPLA2 (7) and have shown that it contains a binding site for phosphatidylinositol 4,5-bisphosphate (PIP2) which activates the enzyme (8 + 43).

Inhibitors and Cellular Studies

Membrane Phenomenon and Surface Dilution Kinetics

Other Novel Enzymes

Oxidized Lipids

Significant References

1. Dennis, E.A., Diversity of Group Types, Regulation, and Function of Phospholipase A2, J.Biol.Chem., 269, 13057-13060 (1994).
2. Balsinde, J. and Dennis, E.A., Function and Inhibition of Intracellular Calcium-Independent Phospholipase A2, J.Biol.Chem., 272, 16069-16072 (1997).
3. Ackermann, E.J., Kempner, E.S., and Dennis, E.A., Ca2+-Independent Cytosolic Phospholipase A2 from Macrophage-Like P388D1 Cells. Isolation and Characterization, J.Biol.Chem., 269, 9227-9233 (1994).
4. Ackermann, E.J., Conde-Frieboes, K., and Dennis, E.A., Inhibition of Macrophage Ca2+-Independent Phospholipase A2 by Bromoenol Lactone and Trifluoromethyl Ketones, J.Biol.Chem., 270 , 445-450 (1995).
5. Balboa, M.A., Balsinde, J., Jones, S.S., and Dennis, E.A., Identity Between the Ca2+-Independent Phospholipase A2 Enzymes from P388D1 Macrophages and CHO Cells, J.Biol.Chem., 272, 8576-8580 (1997).
6. Balboa, M.A., Winstead, M.V., Balsinde, J., Tischfield, J.A., and Dennis, E.A., Novel Group V Phospholipase A2 Involved in Arachidonic Acid Mobilization in Murine P388D1 Macrophages, J.Biol.Chem., 271, 32381-32384 (1996).
7. Pickard, R.T., Chiou, X.G., Strifler, B.A., DeFelippis, M.R., Hyslop, P.A., Tebbe, A.L., Yee, Y.K., Reynolds, L.J., Dennis, E.A., Kramer, R.M., and Sharp, J.D., Identification of essential residues for the catalytic function of 85-kDa cytosolic phospholipase A2. Probing the role of histidine, aspartic acid, cysteine, and arginine, J.Biol.Chem., 271, 19225-19231 (1996).
8. Mosior, M., Six, D.A., and Dennis, E.A., Group IV Cytosolic Phospholipase A2 Binds with High Affinity and Specificity to Phosphatidylinositol 4,5-Bisphosphate Resulting in Dramatic Increases in Activity, J.Biol.Chem., 273, 2184-2191 (1998).
9. Six,D.A. and Dennis,E.A., The Expanding Superfamily of Phospholipase A2 Enzymes: Classification and characterization, Biochim.Biophys.Acta, 1488, 1-19 (2000).
10. Canne,L., Botti,P., Simon,R., Chen,Y., Dennis,E.A., and Kent,S., Chemical Protein Synthesis by Solid Phase Ligation of Unprotected Peptide Segments, J.Am.Chem.Soc., 121, 8720-8727 (1999).

43. Six, D.A., Dennis, E.A., Essential Ca2+-independent role of the group IV A cytosolic phospholipase A2 C2 domain for interfacial activity, J.Biol.Chem., ( Apr 2 2003, epub ahead of print).