Phosphoinositide 3‐kinase and integrin signalling are involved in activation of Bruton tyrosine kinase in thrombin‐stimulated platelets

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Abstract
Bruton tyrosine kinase (Btk) plays a crucial role in the differentiation of B lymphocytes and belongs to the group of Tec kinases, which are characterised by the presence of a pleckstrin homology domain. Here we show that Btk is activated and undergoes tyrosine phosphorylation upon challenge of platelet thrombin receptor, these responses requiring engagement of αIIb/β3 integrin and phosphoinositide 3‐kinase activity. These data unravel a novel signalling pathway involving Btk downstream of an adhesive receptor via a complex regulation implicating the products of phosphoinositide 3‐kinase, which might act to anchor Btk at the membrane.