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The P2Y 12 receptor induces platelet aggregation through weak activation of the α IIb β 3 integrin – a phosphoinositide 3‐kinase‐dependent mechanism
Author(s) -
Kauffenstein G.,
Bergmeier W.,
Eckly A.,
Ohlmann P.,
Léon C.,
Cazenave J.P.,
Nieswandt B.,
Gachet C.
Publication year - 2001
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/s0014-5793(01)02824-1
Subject(s) - wortmannin , apyrase , signal transduction , protein kinase c , phosphoinositide 3 kinase , integrin , ly294002 , phosphorylation , microbiology and biotechnology , receptor , platelet activation , chemistry , p2y receptor , biology , phosphatidylinositol , biochemistry , platelet , protein kinase b , purinergic receptor , immunology
High concentrations of adenosine‐5′‐diphosphate ADP are able to induce partial aggregation without shape change of P2Y 1 receptor‐deficient mouse platelets through activation of the P2Y 12 receptor. In the present work we studied the transduction pathways selectively involved in this phenomenon. Flow cytometric analyses using R‐phycoerythrin‐conjugated JON/A antibody (JON/A‐PE), an antibody which recognizes activated mouse α IIb β 3 integrin, revealed a low level activation of α IIb β 3 in P2Y 1 receptor‐deficient platelets in response to 100 μM ADP or 1 μM 2MeS‐ADP. Adrenaline induced no such activation but strongly potentiated the effect of ADP in a dose‐dependent manner. Global phosphorylation of 32 P‐labeled platelets showed that P2Y 12 ‐mediated aggregation was not accompanied by an increase in the phosphorylation of myosin light chain (P 20 ) or pleckstrin (P 47 ) and was not affected by the protein kinase C (PKC) inhibitor staurosporine. On the other hand, two unrelated phosphoinositide 3‐kinase inhibitors, wortmannin and LY294002, inhibited this aggregation. Our results indicate that (i) the P2Y 12 receptor is able to trigger a P2Y 1 receptor‐independent inside‐out signal leading to α IIb β 3 integrin activation and platelet aggregation, (ii) ADP and adrenaline use different signaling pathways which synergize to activate the α IIb β 3 integrin, and (iii) the transduction pathway triggered by the P2Y 12 receptor is independent of PKC but dependent on phosphoinositide 3‐kinase.