Abstract

MI (myocardial infarction) often triggers severe heart failure and is one of the leading causes of death worldwide. Receptor expression-enhancing protein 5 (REEP5), a member of REEPs, acts as regulators of endoplasmic reticulum (ER) affecting cardiac functions. Based on GSE114695 profile data, REEP5 was decreased in the left ventricle of MI mice. However, its role and potential mechanism in MI remain to be investigated. In the present study, the mouse MI model was established by ligation of the left anterior descending artery. REEP5 expression was downregulated in the infarct penumbra area of MI mice. Next, its role during MI was explored by gain-of-function. Interestingly, REEP5 overexpression improved left ventricular function of mice with MI, accompanied with reduced infarct size. In cardiomyocytes, REEP5 overexpression inhibited ER stress, accompanied with repressive phosphorylation of PERK and IRE1α, and the decreased nuclear translocation of ATF6. Subsequently, REEP5 overexpression downregulated the levels of Chop and cleaved caspase-12, further alleviating ER stress-induced apoptosis, which was consistent with the in vivo results. Moreover, REEP5 was found to bind to C-type lectin member 5 A (CLEC5A), a protein that triggers cardiac dysfunction. CLEC5A, whose expression was elevated in hypoxia-induced cell models, led to cardiomyocyte apoptosis. Noteworthily, REEP5 overexpression markedly abolished the effects of CLEC5A on ER stress-induced apoptosis. Taken together, REEP5 mediated the function of CLEC5A to relieve MI via inhibiting ER stress-induced apoptosis in vivo and in vitro. REEP5 may be a promising target for treating MI.