The STING-IRF3 signaling pathway, mediated by endoplasmic reticulum stress, contributes to impaired myocardial autophagic flux following ischemia/reperfusion.

This study aimed to determine whether endoplasmic reticulum (ER) stress is involved in impaired autophagy after myocardial ischemia/reperfusion I/R (M-I/R) and elucidate the underlying mechanisms. The expression levels of STING and IRF3 phosphorylation increased in M-I/R heart tissues and hypoxia/reoxygenation (H/R)-treated H9c2 cells. The ER stress inhibitor 4-phenylbutyric acid (4-PBA)significantly suppressed the stimulation of STING-IRF3 transcription and alleviatedcardiac dysfunction caused by M-I/R injury. In addition, 4-PBA reversed I/R-induced autophagic flux dysfunction, as demonstrated by a decrease in p62 and LC3 levels. Similarly, the protective effect of STING deficiency on myocardial cell damage was achieved by the recovery of autophagic flux. Conversely, the protective effect of 4-PBA against H/R injury in cardiomyocytes was offset by STING overexpression, wherein the activated STING-IRF3 pathway promoted the expression of Rubicon (a negatively-regulated autophagic molecule) by binding to the Rubicon promoter. Rubicon ablation effectively counteracts the adverse effects of STING overexpression in cardiomyocytes. The data showed that STING-IRF3 signaling of ER stress receptors is particularly important in the progression of physiological M-I/R caused by the inhibition of autophagic flow in vivo and in vitro.