Dr. Woulfe's research interests focus primarily on the intracellular signaling mechanisms of platelet activation and how signaling in platelets contributes to thrombosis in vivo. Agonists that extend formation of the platelet plug generally bind to G protein-coupled receptors on the platelet surface. Dr. Woulfe's previous studies have focused on how platelets become activated by agonists that bind to G protein-coupled receptors and how platelet signaling stabilizes platelet aggregates as they grow. A key finding from these studies was that platelets from mice lacking certain isoforms of the serine/threonine kinase Akt (particularly Akt2) have defects in platelet secretion, fibrinogen binding, and stable aggregate formation. Akt2-/- mice are also resistant to thrombosis in an arterial injury model. In contrast, the Akt substrate, Glycogen synthase kinase (GSK)3beta, is a negative regulator of platelet signaling and thrombosis. Platelets from mice lacking one allele of GSK3beta are hyperresponsive to agonists and the mice are more susceptible to thrombosis than their wildtype counterparts. We have more recently shown that arrestin-2 regulates the function of PI3K and Akt signaling and function in platelets and have new collaborative projects centered on understanding the influence of hyperglycemia/diabetes on platelet function in vitro and in vivo.

Our newest work focuses on understanding novel interactions of platelet surface molecules and how they contribute to platelet signaling and thrombosis.  In this regard, we are focusing on the agonist-dependent interaction of the thrombin receptor PAR4 with the ADP receptor P2Y12.  We are also working to understand the stoichiometry and function of P2Y12 in resting and activated platelets and how two mutations in P2Y12 identified in patients with bleeding disorders may alter the interactions of P2Y12 with itself, G protein, or other receptors.  Finally, we are exploring the role of a novel Ca++-dependent Ca++ channel, termed TMEM16f or anoctamin 6, in the shedding of small platelet fragments called microparticles.  Preliminary data suggest that these platelet-derived microparticles may contribute to thrombosis and understanding the mechanism by which pro-coagulant microparticles are generated may suggest novel ways to inhibit their generation, function and ultimately, reduce cardiovascular risk.