出版社：American Society for Biochemistry and Molecular Biology
摘要：Platelet activation initiates an upsurge in polyunsaturated (18:2 and 20:4) lysophosphatidic acid (LPA) production. The biochemical pathway(s) responsible for LPA production during blood clotting are not yet fully understood. Here we describe the purification of a phospholipase A1 (PLA1) from thrombin-activated human platelets using sequential chromatographic steps followed by fluorophosphonate (FP)-biotin affinity labeling and proteomics characterization that identified acyl-protein thioesterase 1 (APT1), also known as lysophospholipase A-I (LYPLA-I; accession code O75608 ) as a novel PLA1. Addition of this recombinant PLA1 significantly increased the production of sn -2-esterified polyunsaturated LPCs and the corresponding LPAs in plasma. We examined the regioisomeric preference of lysophospholipase D/autotaxin (ATX), which is the subsequent step in LPA production. To prevent acyl migration, ether-linked regioisomers of oleyl- sn -glycero-3-phosphocholine (lyso-PAF) were synthesized. ATX preferred the sn -1 to the sn -2 regioisomer of lyso-PAF. We propose the following LPA production pathway in blood: 1 ) Activated platelets release PLA1; 2 ) PLA1 generates a pool of sn-2 lysophospholipids; 3 ) These newly generated sn-2 lysophospholipids undergo acyl migration to yield sn-1 lysophospholipids, which are the preferred substrates of ATX; and 4 ) ATX cleaves the sn-1 lysophospholipids to generate sn-1 LPA species containing predominantly 18:2 and 20:4 fatty acids.
关键词：lysophospholipid ; acyl protein thioesterase ; autotoxin ; lysophosphatidic acid
