Increased Glycolysis and ATP Production Are Not Prerequisites for Cardiomyocytes Cell Cycle Induction

BACKGROUND: It has been reported that metabolic switch from fatty acid oxidation to glycolysis is associated with cardiomyocyte cell cycle induction. However, it is unknown if increased glycolysis and ATP production are indispensable for cardiomyocyte cell cycle induction. Here, we aim to address this question. METHODS: Cell cycle was induced by overexpression of CCND2 gene or treatment of FGF1 (100 ng/mL) and CHIR99021 (5 µM) on human induced pluripotent stem cells-derived cardiomyocytes (hiPSC-CMs). Contraction inhibition was induced by treatment of verapamil (0.5 μM). Cell cycle was evaluated by immunostaining using antibodies against cell cycle markers. Real-time ATP production and mitochondrial oxidative phosphorylation were determined by Seahorse assay. Metabolic profile was assessed by liquid chromatography-mass spectrometry. RESULTS: Treatment of FGF1 and CHIR99021 induces cell cycle of hiPSC-CMs, reduced carbohydrate metabolism and real-time ATP production from both mitochondria and cytoplasm. Data from RNA Sequencing showed this treatment increased expression of CCND2 and CDK4 and decreased expression of sarcomeric contractile related genes. Overexpression of CCND2 in hiPSC-CMs also induces cell cycle, increased aerobic glycolysis (Warburg effect) and no change of real-time ATP production. Inhibition of contraction via treatment of verapamil resulted in reduced overall metabolism and real-time ATP production. CONCLUSION: Our data suggest that cardiomyocyte cell cycle may be induced without increased glycolysis or real-time ATP production. © FASEB.