Phosphatidic and lysophosphatidic acid production in phospholipase C-and thrombin-treated platelets. Possible involvement of a platelet lipase.
Incubation of 32P-labelled platelets with Clostridium welchii phospholipase C greatly stimulates 32P-incorporation into phosphatidic and lysophosphatidic acids. A net synthesis is demonstrated for both phospholipids, which exhibit identical specific radioactivities. Phosphatidic acid production roughly parallels the phospholipase C-induced aggregation, whereas lysophosphatidic acid appears secondarily during cell lysis. The same qualitative variations are observed during thrombin-induced aggregation. At the physiological pH used throughout the incubations, platelets display no phospholipase A activity towards phosphatidic acid, whereas diglycerides are deacylated by platelet lysates. On the basis of these findings, a mechanism for phosphatidic and lysophosphatidic acid production is proposed, involving a phosphorylation of the di- and monoglycerides formed upon phospholipase C and lipase action. The possible role of such a pathway in regulating arachidonic acid release from phospholipids during platelet activation is discussed.
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D003016:Clostridium perfringens / Q000201:enzymology; D006801:Humans; D066298:In Vitro Techniques; D008049:Lipase / Q000378:metabolism*; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D010740:Phospholipases / Q000378:metabolism / Q000494:pharmacology*; D013552:Swine; D013917:Thrombin / Q000494:pharmacology*
D010712:Phosphatidic Acids; D010740:Phospholipases; D008049:Lipase; D013917:Thrombin