Protein kinase C inhibitors enhance G‐protein induced phospholipase A2 activation in intact human platelets

FEBS Letters

Nucciarelli, Fabio¹  Stasi, Mario¹  Gresele, Paolo²  Iorio, Paolo¹  Vezza, Roberta²  Nenci, Giuseppe G.²  Goracci, Gianfrancesco¹ 

[1] Institute of Medical Biochemistry, University of Perugia, Via del Giochetto, 06100 Perugia, Italy;Institute of Internal and Vascular Medicine, University of Perugia, Via E. Dal Pozzo, 06100 Perugia, Italy

关键词: Phospholipase A2 activation (human platelets);    Protein kinase C inhibitors;    G-Protein;    β-Thromboglobulin release;    Protein phosphatase;    AA;    arachidonic acid;    H-7;    1-(5-isoquinolinylsulfonyl)-2-methylpiperazine;    MAPK;    mitogen-activated protein kinase;    PA;    phosphatidic acid;    PGI2;    prostacyclin;    PKC;    protein kinase C;    PLC;    phospholipase C;    PMA;    phorbol 12-myristate 13-acetate;    cPLA2;    cytosolic phospholipase A2;    sPLA2;    secretable phospholipase A2;    β-TG;    β-thromboglobulin;    TxB2;    thromboxane B2;    WLP;    washed labelled platelets;   

DOI  :  10.1016/0014-5793(96)00117-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Washed intact human platelets were prelabelled with [³H]arachidonic acid ([³H]AA) and stimulated with thrombin or with AIF₄ ⁻, a known unspecific activator of G-proteins. Both stimuli induced the liberation of [³H]AA, the release of β-thromboglobulin (β-TG) and platelet aggregation. PMA did not induce liberation of [³H]AA although it induced β-TG release and aggregation; preincubation with PMA did not modify significantly the amounts of [³H]AA and β-TG released by thrombin or AlF₄ ⁻. Different inhibitors of PKC (staurosporine, H-7 and calphostin C) increased the release of [³H]AA and inhibited β-TG release and aggregation induced by AlF₄ ⁻ but they had no effect when platelets were stimulated with thrombin (0.5 U/ml). Calphostin C was able to release [³H]AA by itself without inducing aggregation or β-TG release. Okadaic acid (a serine/threonine phosphoprotein phosphatase inhibitor) greatly inhibited the release of [³H]AA, β-TG and aggregation in AlF₄ ⁻-stimulated platelets. These results indicate the presence of a G-protein mediated mechanism for the activation of a platelet phospholipase A₂ 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.

【 授权许可】

Unknown