Up-regulated miR-223-3p regulated expressions of autophagy-related genes by targeting FOXO3 that was low-expressed in AF myocardial tissues. (a). MiR-223-3p expression in myocardial tissues was determined by RT-qPCR, U6 was used as an internal control. (b). FOXO3 expression in myocardial tissues was determined by RT-qPCR, β-actin was used as an internal control. (c) The correlation of miR-223-3p with FOXO3 was analyzed by Pearson correlation analysis. (d-f) The expressions of ATG7, LC3B-I, LC3B-II, and p62/SQSTM1 in the myocardial tissues were determined by Western blot, β-actin was used as an internal control. (^^^P < 0.001, vs. AF). (g). FOXO3-3'-UTR containing binding sites of miR-223-3p was predicted by TargetScan. (h). Luciferase assay validated that miR-223-3p targeted FOXO3 in 293 T cells, (^^^P < 0.001, vs. MC). All the experiments were conducted three times. (AF: atrial fibrillation, SR: sinus rhythm, M: miR-223-3p mimic, MC: mimic control)