Vascular Piezo1 in Thrombosis - Thrombotic complications are responsible for one in four deaths. Current anticoagulation strategies directly target coagulation factors, thereby mitigating thrombosis systemically, but at the cost of increased bleeding risk. However, the distribution of coagulation factors and thrombotic propensity varies across the vascular tree. An improved mechanistic understanding of how thrombus forms locally could inform a new generation of therapeutic targets. Mechanical forces vary across vascular beds; yet, how these heterogeneous forces translate into thrombosis remains unresolved. Mechanosensitive ion channels, particularly Piezo1, transduce mechanical stimuli into cellular responses. In studying Piezo1 and coagulation, we found that endothelial Piezo1 activation counters the prothrombotic shift during inflammation by inducing KLF2/4, increasing thrombomodulin, and reducing tissue factor. Piezo1 protein levels increase from static conditions to laminar flow conditions, yet enhanced agonist concentrations are required to potentiate an anti-coagulant response in the laminar flow conditions. Together, these data support the tuning of Piezo1 sensitivity by shear forces. We propose that Piezo1 is a crucial mediator of thrombotic responses to mechanical forces, and that its influence varies significantly across distinct vascular beds. We will evaluate this overarching hypothesis using a combination of pharmacological and genetic tools to modulate Piezo1 channels in both in vitro mechanical activation models, such as flow chambers and strain models, as well as murine models. We will systematically link heterogeneous mechanical forces to distinct Piezo1 signatures across multiple cell types by monitoring Piezo1 protein levels, calcium transduction properties, and the resulting coagulation-associated changes. In vivo we will evaluate the effect of Piezo1 activation on thrombosis across veins, venules, capillaries, arterioles, and arteries. These findings will initiate discovery at the interface of biochemical signaling and mechanotransduction, identifying endothelial pathways that can be targeted locally to stem thrombosis. This proposal outlines a five-year mentored research training program designed to support Dr. Sack’s career development. The applicant has a strong background in endothelial biology and mechanotransduction. This proposal will expand Dr. Sack’s skill set through didactics, workshops, mentoring sessions, and an investigation into Piezo1 mechanotransduction and thrombosis. Dr. Robert Flaumenhaft, the primary mentor, has a distinguished record of mentorship and innovation in the field of thrombosis research. Dr. Sack will receive additional feedback, mentorship, and training through a scientifically relevant and experienced advisory committee that will critically assess the applicant’s progress. In summary, Dr. Sack has created an outstanding environment that fosters success in her career as an independent physician-scientist, dedicated to investigating how mechanical factors contribute to critical illness-associated hemostatic and thrombotic pathologies.
