β-Arrestin-1 reduces acute myocardial infarction via promoting autophagy in cardiomyocytes

Abstract

Background and purpose: β-Arrestins are key regulators of G protein–coupled receptor (GPCR) signaling. Through their function as scaffolding proteins, β-arrestins mediate a range of cellular signaling events. However, the role of β-arrestins during myocardial ischemia remains incompletely understood. In this study, we explored the regulatory effects of β-arrestin-1 on autophagy following myocardial infarction and sought to identify the underlying mechanism. Methods: Acute myocardial infarction was induced by permanent left anterior descending coronary artery ligation. Cardiac function was assessed using echocardiography. β-Arrestin-1, autophagy-related 5 (ATG5), and liver kinase B1 (LKB1) were overexpressed or knocked down using lentivirus-mediated transduction of the gene or short hairpin RNA (shRNA) in cultured primary cardiomyocytes. Oxygen-glucose deprivation (OGD) in cardiomyocytes was used to simulate cardiac ischemia in vitro. Autophagy and apoptosis were assessed by western blot, flow cytometry, and transmission electron microscopy. Cell survival and lactate dehydrogenase (LDH) release were evaluated using the respective kits. Results: β-Arrestin-1 knockout (KO) increased myocardial infarction size, an effect that was associated with decreased autophagy and deterioration of cardiac function. The overexpression of β-arrestin-1 significantly increased autophagy levels and decreased cell apoptosis in cardiomyocytes exposed to OGD, whereas the knockdown of β-arrestin-1 exerted the opposite effect. The protective effect of β-arrestin-1 overexpression was abrogated by ATG5 knockdown. β-Arrestin-1 KO attenuated the myocardial infarction–induced phosphorylation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). In cultured myocytes, the blockade of AMPK or the knockdown of LKB1 inhibited the β-arrestin-1–induced increase in the LC3-II/LC3-I ratio and beclin 1 expression levels and attenuated β-arrestin-1–mediated cardioprotective effects. Conclusions: Collectively, our findings suggested that β-arrestin-1 promotes cardiomyocyte survival under ischemic conditions via the regulation of LKB1/AMPK-dependent autophagy. These findings may be helpful in designing novel therapeutic strategies for myocardial ischemia.