PKCα regulates platelet granule secretion and thrombus formation in mice

Abstract

Platelets are central players in atherothrombosis development in coronary artery disease. The PKC family provides important intracellular mechanisms for regulating platelet activity, and platelets express several members of this family, including the classical isoforms PKCα and PKCβ and novel isoforms PKCδ and PKCθ. Here, we used a genetic approach to definitively demonstrate the role played by PKCα in regulating thrombus formation and platelet function. Thrombus formation in vivo was attenuated in Prkca -/-mice, and PKCα was required for thrombus formation in vitro, although this PKC isoform did not regulate platelet adhesion to collagen. The ablation of in vitro thrombus formation in Prkca -/-platelets was rescued by the addition of ADP, consistent with the key mechanistic finding that dense-granule biogenesis and secretion depend upon PKCα expression. Furthermore, defective platelet aggregation in response to either collagen-related peptide or thrombin could be overcome by an increase in agonist concentration. Evidence of overt bleeding, including gastrointestinal and tail bleeding, was not seen in Prkca -/-mice. In summary, the effects of PKCα ablation on thrombus formation and granule secretion may implicate PKCα as a drug target for antithrombotic therapy.

Multiple alterations of platelet functions dominated by increased secretion in mice lacking Cdc42 in platelets

“…This notion would be in line with studies from other groups demonstrating the significance of degranulation-dependent release of platelet agonists, such as ADP and ATP, for thrombus formation under physiologic conditions. 3,41,42 Furthermore, our results clearly show that effective thrombus formation can still take place under conditions of decreased circulating platelet numbers. 43 In contrast to these observations, Cdc42-deficient mice displayed variable but significantly prolonged bleeding times, indicating impaired platelet plug formation ( Figure 6C).…”

A novel and essential role for FcγRIIa in cancer cell–induced platelet activation

“…16 Mouse WPs were drawn and prepared as previously described. 17,18 Platelet aggregation assay Platelet aggregation was monitored at 37°C with continuous stirring in a PAP-4/8 aggregometer (Bio-Data Corporation). All aggregation experiments were measured against Tyrode buffer as the blank.…”

The kinetics of αIIbβ3 activation determines the size and stability of thrombi in mice: implications for antiplatelet therapy

“…16 DAG is a well-established activator of protein kinase C (PKC) and therefore granule release in platelets. 17,18 PKC-dependent integrin activation depends on positive feedback by the Gi-coupled P2Y12 receptor, 19 which again leads to the activation of Rap1. 11,12,20 Importantly, CalDAG-GEFI-mediated Rap1 activation is rapid but reversible, while P2Y12-mediated Rap1 activation occurs with a delay but is more stable.…”

“…16 DAG is a well-established activator of protein kinase C (PKC) and therefore granule release in platelets. 17,18 PKC-dependent integrin activation depends on positive feedback For personal use only. on May 9, 2018. by guest www.bloodjournal.org From by the Gi-coupled P2Y12 receptor, 19 which again leads to the activation of Rap1.…”