Premium
Protein kinase C inhibitors enhance G‐protein induced phospholipase A 2 activation in intact human platelets
Author(s) -
Iorio Paolo,
Gresele Paolo,
Stasi Mario,
Nucciarelli Fabio,
Vezza Roberta,
Nenci Giuseppe G.,
Goracci Gianfrancesco
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(96)00117-2
Subject(s) - okadaic acid , protein kinase c , calphostin c , thrombin , chemistry , phospholipase c , arachidonic acid , staurosporine , phosphatase , biochemistry , protein kinase a , activator (genetics) , platelet , liberation , phospholipase a2 , platelet activation , phospholipase , calphostin , kinase , phosphorylation , enzyme , biology , receptor , immunology , in vitro
Washed intact human platelets were prelabelled with [ 3 H]arachidonic acid ([ 3 H]AA) and stimulated with thrombin or with AIF 4 − , a known unspecific activator of G‐proteins. Both stimuli induced the liberation of [ 3 H]AA, the release of β‐thromboglobulin (β‐TG) and platelet aggregation. PMA did not induce liberation of [ 3 H]AA although it induced β‐TG release and aggregation; preincubation with PMA did not modify significantly the amounts of [ 3 H]AA and β‐TG released by thrombin or AlF 4 − . Different inhibitors of PKC (staurosporine, H‐7 and calphostin C) increased the release of [ 3 H]AA and inhibited β‐TG release and aggregation induced by AlF 4 − but they had no effect when platelets were stimulated with thrombin (0.5 U/ml). Calphostin C was able to release [ 3 H]AA by itself without inducing aggregation or β‐TG release. Okadaic acid (a serine/threonine phosphoprotein phosphatase inhibitor) greatly inhibited the release of [ 3 H]AA, β‐TG and aggregation in AlF 4 − ‐stimulated platelets. These results indicate the presence of a G‐protein mediated mechanism for the activation of a platelet phospholipase A 2 which is negatively affected by a protein kinase, sensible to putative inhibitors of protein kinase C, and it is activated by a protein phosphatase, sensible to okadaic acid.