Sirtuin1 mitigates hypoxia-induced cardiomyocyte apoptosis in myocardial infarction via PHD3/HIF-1α

BackgroundAcute myocardial infarction (AMI) is a leading cause of mortality, characterized by myocardial ischemia that induces cardiomyocyte apoptosis and subsequent cardiac dysfunction. Sirtuin 1 (Sirt1) has emerged as a key regulator of cell survival and apoptosis, particularly under hypoxic conditions.MethodsAn AMI animal model was established via ligation of the left anterior descending (LAD) coronary artery. Gene expression in the infarcted region was evaluated at various time points. Sirt1 overexpression and control lentivirus were administered to the peri-infarct region of mice heart. After LAD ligation, assessment on myocardial infarct size, cardiac function, and cardiomyocyte apoptosis were performed. In vitro, primary mouse cardiomyocytes subjected to hypoxia were analyzed for gene expression, while interactions among Sirt1, Phd3, and Hif-1 alpha were explored using diverse treatment approaches.ResultsA significant reduction in Sirt1 and Phd3 expression, along with an increase in Hif-1 alpha and cleaved caspase-3, was observed in a time-dependent manner post-myocardial infarction (MI). In vitro findings revealed that hypoxia decreased nuclear Sirt1 and cytoplasmic Phd3 levels while promoting a time-dependent increase in Hif-1 alpha and cleaved caspase-3. Furthermore, Sirt1 overexpression enhanced Phd3 expression in cardiomyocytes, suppressed Hif-1 alpha and cleaved caspase-3 levels, and alleviated hypoxia-induced cardiomyocyte apoptosis. Notably, knockdown of Phd3 negated Sirt1's inhibitory effect on Hif-1 alpha, whereas Hif-1 alpha knockdown promoted Sirt1 expression. Sirt1 overexpression reduced infarct size, decreased cardiomyocyte apoptosis, and improved cardiac function.ConclusionsSirt1 effectively reduces cardiomyocyte apoptosis and myocardial infarction size while enhancing cardiac function post-MI, primarily through the Phd3/Hif-1 alpha signaling pathway.