title: Selective secretion of protein kinase C isozymes by thrombin-stimulated human platelets.
abstract: The protein kinase C (PKC) was secreted from thrombin-stimulated human platelets in a time- and dose-dependent manner. The PKC specific inhibitors Ro31-8220 (0.05 microM) and GF 109203X (0.5 microM) totally inhibited the secreted kinase activity. Western blot analysis of the secretory components showed reactivity to PKCalpha, PKCbetaII, and PKCdelta antibodies, but not to PKCbetaI, and p42/44 MAPK, although they were present in lysed platelets. The fractionation of platelets secreted components showed that PKC activity increased in both soluble and microparticle fractions after thrombin treatments. This is the first report demonstrating that activated human platelets selectively secrete protein kinase C isozymes. Protein kinase C secreted by platelets in this unique manner may have an extracellular role in the plasma, and may regulate cellular functions, including remodeling of vascular endothelial cells.
authors.affiliation: Department of Pharmacology, School of Medicine, University of Missouri-Columbia, Columbia, MO 65212, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Hillen
authors.forename: A R
authors.initials: AR
authors.lastname: Aroor
authors.forename: S D
authors.initials: SD
authors.lastname: Shukla
mesh_terms: D001792:Blood Platelets / Q000187:drug effects / Q000201:enzymology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007211:Indoles / Q000494:pharmacology; D007527:Isoenzymes / Q000097:blood; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000097:blood*; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D011494:Protein Kinases / Q000097:blood; D013917:Thrombin / Q000494:pharmacology*
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; D007527:Isoenzymes; D008301:Maleimides; D007770:L-Lactate Dehydrogenase; D011494:Protein Kinases; C496628:PRKCA protein, human; C497258:PRKCD protein, human; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051571:Protein Kinase C-alpha; D051745:Protein Kinase C-delta; D013917:Thrombin; C070515:bisindolylmaleimide I; C064758:Ro 31-8220