The glycoprotein VI-phospholipase Cgamma2 signaling pathway controls thrombus formation induced by collagen and tissue factor in vitro and in vivo.

OBJECTIVE: Both collagen and tissue factor can be initiating factors in thrombus formation. We investigated the signaling pathway of collagen-induced platelet activation in interaction with tissue factor-triggered coagulation during the thrombus-forming process. METHODS AND
RESULTS: In murine blood flowing over collagen, platelet exposure of phosphatidylserine and procoagulant activity, but not adhesion, completely relied on each of the following signaling modules: glycoprotein VI (GPVI), FcR gamma-chain, Src kinases, adaptor protein LAT, and phospholipase Cgamma2 (PLCgamma2). On flow in the presence of tissue factor, these signaling components were essential for platelet aggregation and greatly enhanced fibrin clot formation. Collagen-stimulated thrombin generation relied on the presence and activity of GPVI, FcR gamma-chain, Src kinase, LAT, and PLCgamma2. The physiological importance of this GPVI pathway was shown in a FeCl3-induced in vivo murine thrombosis model. In both venules and arterioles, signaling through GPVI, FcR gamma-chain, and Src kinases enhanced the formation of phosphatidylserine-exposing and fibrin-rich thrombi.
CONCLUSIONS: The GPVI-PLCgamma2 activation pathway regulates collagen-dependent coagulation in venous and arterial thrombus formation.