Unveiling the Cardioprotective Potential of HY-021068: Dual Modulation of Calcium Homeostasis and Endoplasmic Reticulum Stress in Myocardial Infarction in Mice

Abstract

Acute myocardial infarction (AMI) remains a leading cause of death worldwide and is characterized by abrupt coronary occlusion and subsequent ischemic cardiomyocyte injury. Increasing evidence implicates endoplasmic reticulum (ER) stress and disordered calcium handling as central drivers of post-infarction dysfunction. Here, we investigated whether HY-021068 (HY), a thromboxane synthase inhibitor under clinical evaluation, confers cardioprotection by restoring sarco/endoplasmic reticulum Ca²?-ATPase 2a (SERCA2a)-dependent calcium homeostasis and suppressing ER stress. AMI was induced in C57BL/6 mice by left anterior descending coronary artery ligation, and an oxygen–glucose deprivation/reperfusion (OGD/R) model was established in AC16 cardiomyocytes. Infarct size and tissue injury were assessed by TTC staining, H&E and Masson staining, and cardiac function was quantified by echocardiography. Intracellular reactive oxygen species (ROS) and Ca²? levels were measured using DCFH-DA and Fluo-4 AM, respectively. Mitochondrial ultrastructure and function were evaluated by transmission electron microscopy, JC-1 membrane potential assays, and ATP quantification. Key proteins involved in calcium cycling, ER stress, and thromboxane signaling were analyzed by immunoblotting and immunostaining.HY treatment reduced infarct size, attenuated myocardial fibrosis, and improved left ventricular systolic function. In vitro, HY decreased OGD/R-induced cytosolic Ca²? overload, lowered ROS accumulation, and restored mitochondrial membrane potential and ATP production. Mechanistically, HY increased SERCA2a expression and shifted the calcium-handling program toward SR Ca²? reuptake, accompanied by reduced expression of IP3R and NCX-1 and suppression of ER stress markers (GRP78, ATF6, and CHOP). Consistent with its pharmacological class, HY inhibited platelet aggregation and modulated thromboxane-related proteins, including COX-1, TBXAS-1, and PGD.Collectively, these data indicate that HY exerts cardioprotective effects in AMI by dual modulation of calcium homeostasis and ER stress, with SERCA2a as a key molecular node. HY therefore represents a promising multi-target candidate for ischemic heart disease.