Metrnl activates the LKB1/AMPK signaling in cardiomyocytes. (A) Heatmap showing the effects of Metrnl on the components of AMPK array. (B) Top ten signaling protein induced by Metrnl. (C) Metrnl dose- and time-dependently induced AMPK phosphorylation. (D) Effects of Metrnl on HG-induced downregulation of phosphorylated AMPK. (E) Effects of Metrnl shRNA on HG-induced downregulation of phosphorylated AMPK. (F) Cardiomyocytes were pretreated with STO-609 (0.8 μM) or Takinib (10 mM) for 30 min, and challenged by Metrnl (0.2 μg/ml) for 30 min, and then stimulated for HG for 48 h. Cardiomyocytes were pretreated with LKB1 siRNA (100 nM) for 6 h, and challenged by Metrnl (0.2 μg/ml) for 30 min, and then stimulated for HG for 48 h. Western blot was used to determine phosphorylated AMPK. (G) Effects of Metrnl on HG-induced downregulation of phosphorylated LKB1. (H) Effects of Metrnl shRNA on HG-induced downregulation of phosphorylated LKB1. n = 4. *P < 0.05 versus 0 μg/ml, 0 min, NG, Con, Con shRNA, †P < 0.05 versus HG + Con shRNA, Metrnl or HG.