2024 AIChE Annual Meeting
Effects of Protac Mediated BTK Degradation on Platelet Function
Platelets are small, anucleate cell fragments in human blood that function to regulate hemostasis and thrombosis. Bruton’s tyrosine kinase (BTK) regulates platelet signaling and activation, and small molecule BTK inhibitors like Ibrutinib act by irreversibly binding to BTK active sites and blocking signal propagation, where scaffolding activities of BTK remain intact. In contrast, proteolysis targeting chimeras (PROTACs) target specific proteins of interest for ubiquitination, resulting in near-complete proteasomal degradation. The PROTAC DD-03-171 specifically targets BTK for degradation to eliminate BTK signaling and scaffolding activities. We compared the effects of DD-03-171 and ibrutinib on platelet adhesion and spreading as well as platelet aggregation. Western blot analysis confirmed a loss of BTK expression in platelets following 2 h incubation with DD-03-171. Loss of BTK expression inhibited platelet aggregation as well as platelet spreading on surfaces of fibrinogen. These observations were comparable to inhibition of platelet BTK ibrutinib, which was used as a control. This study demonstrates that DD-03-171 effectively promotes the targeted degradation of BTK in platelets and highlights the potential of PROTACs experimental as well as therapeutic tools to specifically manipulate platelet signaling and platelet physiological responses.