1-palmitoyl-2-arachidonoyl-sn-phosphatidylcholine (PAPC), is a naturally occuring phospholipid containing polyunsaturated arachidonic acid, which is a common lipid in mammalian cell membranes and lipoproteins. PAPC can be used as an unoxidized control in experiments utilizing oxidized PAPC (OxPAPC; cat. # HC4035/HC4036). OxPAPC, is a prototypic biologically active oxidized phospholipid first isolated from LDL minimally modified by oxidation (MM-LDL). OxPAPC is an active principle of MM-LDL and mimicks several pro- and anti-inflammatory effects induced by oxidized lipoproteins. Oxidation of PAPC generates two groups of oxidized phospholipids containing either fragmented or oxygenated sn-2 residues. The best-characterized fragmented species contain a five-carbon sn-2 residue bearing omega-aldehyde or omega-carboxyl groups. Oxygenation of arachidonic acid residue produces phospholipids containing esterified isoprostanes. Both fragmented and oxygenated species can regulate immune reactions. Pro-inflammatory effects of OxPAPC induce stimulation of endothelial cells to bind monocytes and induction of tissue clotting factor, IL-8, MCP-1, G-CSF and other mediators of atherothrombosis. Anti-inflammatory effects of OxPAPC are mediated by induction of protective enzymes such as heme oxygenase-1 and suppression of innate immune responses to bacterial lipopolysaccharide (LPS) due to inhibition of LPS recognition by LPS-binding protein (LBP) and CD14. OxPAPC is active in vivo and was shown to protect mice from lethal endotoxin shock. Biological activities of OxPAPC are mediated by a variety of signal transduction mechanisms, including elevation of cAMP and Ca2+ levels, activation of MAP kinases, PI-3-kinase and small GTPases Rac-1 and Cdc42. OxPAPC-induced protein synthesis is mediated by transcription factors such as Egr-1, NFAT, CREB, PPAR-alpha, PPAR-gamma, but does not involve NFkB-dependent transcription.
1. For use of total amount in once: Add buffer or medium used in the experiment and resuspend lipids by vigorous vortexing for at least 30 seconds. Optimal working concentrations are up to 100 µg/ml. Do not exceed concentrations of 0.5 mg/ml since PAPC is poorly soluble in water. Sonicate if necessary to ensure better resuspension of PAPC. PAPC is used as negative control for OxPAPC. The concentration range in which PAPC can be used is dependent on the cell type and should be equal to OxPAPC, usually below 100 µg/ml. Please note that PAPC can be oxidized by cells.
2. For partially use of amount: Add chloroform to the vial to obtain lipid concentration of 1 to 10 mg/ml and vortex. Aliquot PAPC solution into sterile glass (optimal) or polypropylene cell culture tubes. Before use check if the tubes are resistant to chloroform. Evaporate chloroform under a stream of nitrogen or argon gas with simultaneous vortexing in order to obtain a thin film of lipid on the tube walls. Continue according to 1.