Faculty

EDWARD A. DENNIS

• Professor of Pharmacology and Chemistry & Biochemistry
• Director of LIPID MAPS Consortium

TEL: 858-534-3055

FAX: 858-534-7390

email: edennis@ucsd.edu

website: http://cobra.ucsd.edu/

Key Words: Biochemistry: phospholipase A₂, singal transduction in macrophages, mechanism, prostaglandin regulation, mass spec of lipids and proteins.

Our laboratory is focused on understanding the regulation of lipid second messengers and signal transduction processes and especially the role of various phospholipases in their generation. Special attention is paid to the cytosolic, secreted, and membrane-bound phospholipase A2s (PLA2) responsible for the control of prostaglandin and leukotriene biosynthesis in macrophage cells. These are produced from arachidonic acid released by PLA2 upon cell stimulation. Our goal is to characterize and elucidate the regulatory mechanisms of various phospholipase A2s both in vitro and in the intact cell.

In our studies on the regulation and detailed mechanism of action of PLA2 at membrane and other lipid-water interfaces, we have developed in vitro systems for studying their detailed mechanism of action. PLA2s from various sources are currently receiving a great deal of attention because they represent the smallest (molecular weight 13,000) and perhaps the simplest enzymes of complex lipid metabolism known and are ideally suited for mechanistic studies. PLA2s have several kinds of phospholipid binding sites including activator sites, interfacial sites, and catalytic sites. It is important to define the precise role of the amino acid residues involved in these interactions as well as elucidating the conformation and physical state of the phospholipid in mixed micelles and membranes. The laboratory is now carrying out site-directed mutagenesis on various PLA2s derived from human genes and mass spectrometric analysis of surface interactions.

Our laboratory also designs and synthesizes chemical inhibitors of phospholipase A2. Many different inhibitor classes have been developed and are being studied using in vitro, ex vivo and in vivo animal models. We are also studying synthetic oxidized phospholipids and their role in LDL scavenger receptor uptake, autoantibody formation, and apoptosis all of which are processes that lead to atherosclerosis. In summary, our laboratory utilizes organic synthetic approaches, enzyme kinetics, molecular biology, site-specific mutagenesis, cell and tissue culture, and mass spectometric techniques as well as traditional biochemical approaches in attacking phospholipase and membrane problems.
SELECTED PUBLICATIONS

Correlation of Antiphospholipid Antibody Recognition with the Structure of Synthetic Oxidized Phospholipds: Importance of Schiff Base Formation and Aldo Condensation. With P. Friedman, S. Horkko, D. Steinberg, and J. L. Witztum. J. Biol. Chem. 277, 7010 (2002).

Novel 2-Oxo Amide Inhibitors of Human Group IVA Phospholipase A2. With G. Kokotos, S. Kotsovolou, D. A. Six, V. Constantinou-Kokotou, and C. C. Beltzner. J. Med. Chem. 45, 2891 (2002).

Essential Ca2+ -Independent Role of the Group IVA Cytosolic Phospholipase A2C2 Domain for Interfacial Activity. With D.A. Six. J. Biol. Chem. 278, 23842 (2003).

Handbook of Cell Signalling, with R.A. Bradshaw. Academic Press/Elsevier, Vol. 1, pp 1-747; Vol. 2, pp 1-899; Vol. 3, pp 1-709. Also, CD-Rom Version, (2003).

Protection from Cytotoxicity of ExoU-expressing Pseudomonas Aeruginosa by Phospholipase A2 Inhibitors.With. R. Phillips, D.A. Six, and P. Ghosh. J. Biol. Chem. 278 41326-41332 (2003).

Localization of Group V Phospholipase A2 in Caveolin-enriched Granules in Activated P388D1 Macrophage-like Cells. With M.A. Balboa, G. Gaietta, Y. Shirai, M.H. Ellisman, and J. Balsinde. J. Biol. Chem. 278, 48059-48065 (2003).

Phospholipid Binding and the Activation of Group IA Secreted Phospholipase A2. With S.C. Boegeman and R.A. Deems. Biochemistry. 43, 3907-3916 (2004).