Inhibition of phosphatidic acid production and lysophospholipid formation in collagen-stimulated human platelets by staurosporine, a protein kinase inhibitor.
To investigate a possible regulatory role of protein kinase C (PKC) on collagen-induced phospholipase activity, human platelets were prelabelled with either [3H] arachidonic acid or [14C]stearic acid and stimulated with collagen (2 micrograms/ml) in the presence or absence of the protein kinase inhibitor, staurosporine (1 microM). The collagen-induced release of [3H]arachidonic acid and formation of [14C]stearoyl-labelled lysophospholipids was inhibited by prior incubation with staurosporine, as was the formation of 3H-labelled thromboxane B2, thereby suggesting inhibition of the collagen-induced phospholipase A2 activity. The degradation of phosphatidylinositol (PI) and elevation of phosphatidic acid (PA) in platelets prelabelled with either radiotracer were also completely blocked by staurosporine pretreatment, indicating a suppression of collagen-stimulated phospholipase C activity. Suppressed phospholipase C activity may have been due to diminished thromboxane A2 formation since treatment with the dual cyclo-oxygenase/lipoxygenase inhibitor, BW755C, also resulted in an inhibition of the collagen-stimulated loss of 14C-labelled PI and rise in PA by 75-80%. Our results suggest that protein kinase, possible PKC, may be involved in the regulation of these phospholipases in collagen-stimulated human platelets.
Thomas
L M
LM
Department of Nutritional Sciences, University of Guelph, Ontario, Canada.
Holub
B J
BJ
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D015772:4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; D000470:Alkaloids / Q000494:pharmacology*; D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000032:analysis; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D003094:Collagen / Q000037:antagonists & inhibitors*; D006801:Humans; D008246:Lysophospholipids / Q000096:biosynthesis*; D010712:Phosphatidic Acids / Q000096:biosynthesis*; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D015398:Signal Transduction / Q000502:physiology; D019311:Staurosporine; D013229:Stearic Acids / Q000378:metabolism*; D013929:Thromboxane B2 / Q000032:analysis; D010738:Type C Phospholipases / Q000378:metabolism*
D000470:Alkaloids; D001095:Arachidonic Acids; D008246:Lysophospholipids; D010712:Phosphatidic Acids; D011450:Prostaglandin Endoperoxides, Synthetic; D047428:Protein Kinase Inhibitors; D013229:Stearic Acids; D016718:Arachidonic Acid; D013929:Thromboxane B2; D015772:4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyrazol-3-amine; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D003094:Collagen; D010741:Phospholipases A; D054467:Phospholipases A2; D010738:Type C Phospholipases; D019311:Staurosporine