2-guanidine-4-methylquinazoline inhibits platelet activation and thrombosis by targeting the acid-sensing ion channel 3

Platelets are key mediators of hemostasis and thrombosis. Acid-sensing ion channel 3 (ASIC3), a proton-gated cation channel, can be directly activated at pH 7.4 by the synthetic compound 2-guanidine-4-methylquinazoline (GMQ). However, the role of GMQ in platelet activation and its potential dependence on ASIC3 remain unclear. This study investigated whether GMQ modulates platelet function at physiological pH (7.4), whether this regulation is mediated by ASIC3, and what the underlying molecular mechanisms are. We found that GMQ significantly suppressed platelet activation in both human and murine platelets at pH 7.4 and attenuated thrombus formation and hemostatic function in mice. ASIC3 was confirmed to be functionally expressed in human and murine platelets. Although ASIC3 deficiency did not affect basal platelet characteristics or platelet activation at pH 7.4, it markedly diminished GMQ-mediated suppression of platelet activation, thrombosis, and hemostasis. Mechanistically, GMQ enhanced cyclic adenosine monophosphate (cAMP) production and promoted protein kinase A (PKA) Thr197 phosphorylation through interaction with ASIC3-cyclase-associated protein 1 (CAP1), thereby suppressing platelet function. Overall, this study demonstrates, for the first time, that GMQ inhibits platelet activation and thrombosis under physiological pH by targeting ASIC3 and activating the CAP1/cAMP/PKA signaling pathway. These findings suggest that targeting the non-proton domain of ASIC3 at physiological pH may represent a novel and promising antiplatelet therapeutic strategy.