Activation of ASIC3 attenuates thrombogenesis: a self-protective mechanism of the body
P Zhang, K D Zhang, H W Yu, Y Y Su, T T Zhang, J F ZhangAbstract
Background and aims
Platelets serve as central regulators of hemostasis and thrombogenesis. While low pH has long been known to suppress platelet activation, the underlying molecular mechanism has not been fully elucidated. Notably, local pH markedly declines following myocardial infarction (MI). Acid-sensing ion channel 3 (ASIC3) detects extracellular acidification and regulates associated pathophysiological responses. In this study, we aimed to establish ASIC3 as a primary platelet pH-sensing receptor and investigate its potential protective role in post-MI thrombogenesis.
Methods
Platelet-specific ASIC3-deficient mice (Asic3-/-) were employed to assess the role of ASIC3 in low pH-induced platelet activation through functional assays. The contribution of ASIC3 in low pH-induced thrombogenesis was evaluated using transgenic mice subjected to established respiratory or metabolic (RA or MA) acidosis models and thrombosis assays. ASIC3-dependent regulatory mechanisms were investigated via mass spectrometry, co-immunoprecipitation, immunofluorescence, molecular docking/dynamics simulations, enzyme-linked immunosorbent assay, and western blotting. MI was induced by permanent left anterior descending coronary artery ligation to evaluate the role of ASIC3 in post-ischemic cardiac pathology. Platelet ASIC3 expression in patients with MI was quantified across mRNA and protein dimensions.
Results
Our findings confirmed that extracellular low pH significantly suppresses the activation of human and murine platelets and low pH attenuates carotid arterial and pulmonary or hepatic thrombogenesis in mouse models with RA or MA. Furthermore, ASIC3 is expressed in human and mouse platelets and serves as a dominant acid-sensing receptor on platelets. In vivo studies established that ASIC3 is essential for acid-mediated thrombosis inhibition. Mechanistically, low pH enhanced cyclic adenosine monophosphate (cAMP) production and promoted protein kinase A (PKA) phosphorylation at Thr-197 via ASIC3-adenylyl cyclase (AC6) interaction, thereby suppressing platelet activation. In addition, ASIC3 deficiency in platelets aggravated post-MI microthrombosis and worsened cardiac dysfunction in mice. Clinically, reduced ASIC3 expression was detected in platelets from MI patients with high thrombus burden, indicating a potentially important protective role of platelet ASIC3.
Conclusions
Our study demonstrates that low pH activates ASIC3 to attenuate platelet activation and thrombogenesis via the AC6-cAMP-PKA signaling axis. Our findings position ASIC3 as a molecular rheostat attenuating thrombogenesis during acidotic stress. Diverse pathological states—including MI, stroke, acidosis, and inflammation—feature a significant pH decrease. This pathway constitutes an endogenous protective mechanism that downregulates platelet reactivity in acidic environments, thereby restricting the progression of pathological thrombosis.Graphic AbstractResults