Ablation of Cardiac TIGAR Preserves Myocardial Energetics and Cardiac Function in the Pressure Overload Heart Failure Model

Despite the advances in medical therapy, the morbidity and mortality of heart failure (HF) remain unacceptably high. HF results from reduced metabolism-contraction coupling efficiency, so the modulation of cardiac metabolism may be an effective strategy for therapeutic interventions. Tumor suppressor p53 and its downstream target TP53-induced glycolysis and apoptosis regulator (TIGAR) are known to modulate cardiac metabolism and cell fate. In order to investigate TIGAR's function in HF, we compared myocardial metabolic and functional outcomes between TIGAR knockout (TIGAR-/-) mice and wild-type (TIGAR+/+) mice subjected to chronic thoracic transverse aortic constriction (TAC), a pressure-overload HF model. In wild-type mice hearts, p53 and TIGAR increased markedly during HF development. Eight weeks after TAC surgery, the left ventricular (LV) dysfunction, fibrosis, oxidative damage, and myocyte apoptosis were significantly advanced in wild-type than in TIGAR-/- mouse heart. Further, cardial high-energy phosphates in wild-type hearts were significantly decreased compared to those of TIGAR-/- mouse heart. lucose oxidation and glycolysis rates were also reduced in isolated perfused wild-type hearts following TAC than those in TIGAR-/- hearts, which suggest that the upregulation of TIGAR in HF causes impaired myocardial energetics and function. The effects of TIGAR knockout on LV function were also replicated in tamoxifen (TAM)-inducible cardiac-specific TIGAR knockout mice (TIGARflox/flox/ Tg(Myh6-cre/Esr1) mice). The ablation of TIGAR during pressure-overload HF preserves myocardial function and energetics. Thus, cardiac TIGAR targeted therapy to increase glucose metabolism will be a novel strategy for HF.