title: Procoagulant and prothrombotic activation of human erythrocytes by phosphatidic acid.
abstract: Increased phosphatidic acid (PA) and phospholipase D (PLD) activity are frequently observed in various disease states including cancers, diabetes, sepsis, and thrombosis. Previously, PA has been regarded as just a precursor for lysophosphatidic acid (LPA) and diacylglycerol (DAG). However, increasing evidence has suggested independent biological activities of PA itself. In the present study, we demonstrated that PA can enhance thrombogenic activities in human erythrocytes through phosphatidylserine (PS) exposure in a Ca(2+)-dependent manner. In freshly isolated human erythrocytes, treatment of PA or PLD induced PS exposure. PA-induced PS exposure was not attenuated by inhibitors of phospholipase A(2) or phosphatidate phosphatase, which converts PA to LPA or DAG. An intracellular Ca(2+) increase and the resultant activation of Ca(2+)-dependent PKC-alpha appeared to underlie the PA-induced PS exposure through the activation of scramblase. A marginal decrease in flippase activity was also noted, contributing further to the maintenance of exposed PS on the outer membrane. PA-treated erythrocytes showed strong thrombogenic activities, as demonstrated by increased thrombin generation, endothelial cell adhesion, and erythrocyte aggregation. Importantly, these procoagulant activations by PA were confirmed in a rat in vivo venous thrombosis model, where PA significantly enhanced thrombus formation. In conclusion, these results suggest that PA can induce thrombogenic activities in erythrocytes through PS exposure, which can increase thrombus formation and ultimately contribute to the development of cardiovascular diseases.
authors.affiliation: College of Pharmacy, Seoul National Univ., Seoul 151-742, Korea.
authors.forename: Ji-Yoon
authors.initials: JY
authors.lastname: Noh
authors.forename: Kyung-Min
authors.initials: KM
authors.lastname: Lim
authors.forename: Ok-Nam
authors.initials: ON
authors.lastname: Bae
authors.forename: Seung-Min
authors.initials: SM
authors.lastname: Chung
authors.forename: Sang-Wook
authors.initials: SW
authors.lastname: Lee
authors.forename: Kyung-Mi
authors.initials: KM
authors.lastname: Joo
authors.forename: Sin-Doo
authors.initials: SD
authors.lastname: Lee
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Chung
mesh_terms: D000818:Animals; D001777:Blood Coagulation / Q000187:drug effects; D002118:Calcium / Q000097:blood; D002448:Cell Adhesion; D002478:Cells, Cultured; D004195:Disease Models, Animal; D042783:Endothelial Cells / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004903:Erythrocyte Aggregation; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D008297:Male; D010711:Phosphatidate Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism; D010712:Phosphatidic Acids / Q000097:blood*; D010718:Phosphatidylserines / Q000097:blood; D064801:Phospholipase A2 Inhibitors; D010739:Phospholipase D / Q000097:blood; D054467:Phospholipases A2 / Q000097:blood; D049294:Phospholipid Transfer Proteins / Q000378:metabolism; D051571:Protein Kinase C-alpha / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D013917:Thrombin / Q000378:metabolism; D013925:Thromboplastin; D013927:Thrombosis / Q000097:blood* / Q000139:chemically induced; D013997:Time Factors
chemical_list: D004791:Enzyme Inhibitors; D010712:Phosphatidic Acids; D010718:Phosphatidylserines; D064801:Phospholipase A2 Inhibitors; D049294:Phospholipid Transfer Proteins; D013925:Thromboplastin; C496628:PRKCA protein, human; D051571:Protein Kinase C-alpha; D054467:Phospholipases A2; D010711:Phosphatidate Phosphatase; D010739:Phospholipase D; D013917:Thrombin; D002118:Calcium