Abstract
Platelet shape and volume changes are early mechanical events contributing to platelet activation and thrombosis. Here, we identify single-nucleotide polymorphisms in leucine-rich repeat-containing 8 (LRRC8) protein subunits that form the volume-regulated anion channel (VRAC), which are independently associated with altered mean platelet volume. LRRC8A is required for functional VRAC in megakaryocytes (MKs) and regulates platelet volume; adhesion; and agonist-stimulated activation, aggregation, adenosine triphosphate (ATP) secretion, and calcium mobilization. MK-specific LRRC8A conditional knockout mice have reduced laser injury-induced cremaster arteriolar thrombus formation and prolonged FeCl3 induced carotid arterial thrombosis without prolonged bleeding times. Mechanistically, platelet LRRC8A mediates swell-induced cytosolic ATP release to amplify agonist-stimulated calcium-phosphoinositide 3-kinase-protein kinase B signaling. Small-molecule LRRC8 channel inhibitors recapitulate defects observed in LRRC8A-null platelets in vitro and in vivo. These studies identify the mechanoresponsive LRRC8 channel complex as an ATP release channel in platelets, which positively regulates platelet function and thrombosis, providing a proof of concept for a novel antithrombotic drug target.