Effects of oxidized phospholipids on smooth muscle cells

Research project P 14714 Effects of oxidized phospholipids on smooth muscle cells Albin HERMETTER 09.10.2000 OxLDL plays a role not only in atherogenesis but also more extensively in the development of the structure typical of the atherosclerotic lesion, with focal excessive growth alternating with necrosis. Cellular uptake and biological properties of oxLDL largely depend on the type and degree of lipoprotein modification. Mildly oxidized LDL has undergone antioxidant depletion and oxidation of polyunsaturated phospholipids with little or no protein modification. It has been demonstrated that the oxidized lipids are entirely responsible for the observed biological activity of this particle. The submitted project is aimed at elucidating the biophysical and biochemical mechanisms determining the effects of oxidized phospholipids on proliferation and death of aortic smooth muscle cells as pertinent to their role in the development of atherosclerosis. This goal implies knowledge of the import of oxidized phospholipids into the cells, the physical and chemical modifications of the cellular membranes, and the signal transduction pathways that are activated as a consequence of the physical and/or chemical activity of the respective compounds. To attain the project goals as outlined above we propose the following program: 1. Synthesize chemically defined diacyl, alkylacyl, and alkenylacyl glycerophospholipids containing short polar and apolar sn-2-acyl chains, and suitably labeled fluorescent analogs. 2. Study the import of these lipids from lipoproteins, lipid-albumin complexes and protein-free lipid vesicles into the plasma membrane of SMCs and their further partition between subcellular compartments eventuelly followed by biochemical modification. 3. Determine the physical effects (lipid mobility) and chemical modifications (of reactive amino and sulfhydryl groups of proteins and lipids) in the plasma membrane as induced by the above compounds. 4. Study cell proliferation and cell death depending on the type and concentration of the short chain phospholipids. 5. Identify representative signal transduction components and pathways that are activated by the different types of short-chain phospholipids under defined conditions of cell growth or death.