title: Differential regulation of P-selectin expression by protein kinase A and protein kinase G in thrombin-stimulated human platelets.
abstract: P-selectin is rapidly translocated from platelet alpha-granules following activation. Intracellular cyclic AMP (cAMP) is a potent inhibitory pathway that results in global downregulation of platelet activation. While cAMP-dependent protein kinase (PKA) has long been considered as the main mediator of cAMP-dependent effects, no study has yet evaluated its effect on P-selectin expression in human platelets. Pretreatment of thrombin-stimulated platelets with forskolin resulted in a concentration- dependent inhibition of P-selectin expression that correlated with adenylyl cyclase activity. Inhibition of PKA with H-89 reversed cAMP-induced inhibition of P-selectin while cGMP-dependent protein kinase (PKG) inhibition with KT5823 significantly potentiated cAMP-dependent inhibition of P-selectin. Similar results were also observed in a platelet/neutrophil binding assay. In conclusion, cAMP-induced inhibition of P-selectin expression is, in large part, mediated through activation of PKA. PKG appears to be solicited for P-selectin expression when cAMP levels are elevated which suggest a cAMP/PKG-dependent pathway of platelet activation.
authors.affiliation: Montreal Heart Institute, Montreal, Quebec, Canada.
authors.forename: Danielle
authors.initials: D
authors.lastname: Libersan
authors.forename: Guy
authors.initials: G
authors.lastname: Rousseau
authors.forename: Yahye
authors.initials: Y
authors.lastname: Merhi
mesh_terms: D000262:Adenylyl Cyclases / Q000187:drug effects / Q000378:metabolism; D000470:Alkaloids / Q000494:pharmacology; D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002227:Carbazoles; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000502:physiology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D006152:Cyclic GMP / Q000502:physiology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D007211:Indoles; D007546:Isoquinolines / Q000494:pharmacology; D009504:Neutrophils / Q000378:metabolism; D019007:P-Selectin / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation; D015539:Platelet Activation / Q000187:drug effects*; D011499:Protein Processing, Post-Translational; D015290:Second Messenger Systems / Q000502:physiology*; D013449:Sulfonamides; D013917:Thrombin / Q000494:pharmacology*
chemical_list: D000470:Alkaloids; D002227:Carbazoles; D004791:Enzyme Inhibitors; D007211:Indoles; D007546:Isoquinolines; D019007:P-Selectin; D013449:Sulfonamides; C073601:KT 5823; D005576:Colforsin; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D013917:Thrombin; D000262:Adenylyl Cyclases; D006152:Cyclic GMP; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide