Defects in auxiliary fuel oxidation and mitochondrial pyruvate transport mark transition to overt heart failure in Tgαq*44 mice

Defective catabolism of alternative and glucose-sparing fuel sources has recently been implicated in the development of cardiovascular and metabolic diseases, including heart failure (HF), but the molecular mechanisms and a causal relationship linking them to altered glucose metabolism are unknown. Herein, alterations in cardiac protein expression in an established HF model (Tgαq*44 mice) were explored at different ages (4−14 months) in relation to changes in energy substrate preference, high-energy phosphate metabolism, and a snapshot of plasma metabolites. A small cohort of HF cases (n = 20) and non-failing controls (n = 18) was also used to confirm translational value of the findings. The progression of HF in Tgαq*44 mice was characterised by an increased reliance on glucose along with reduced mitochondrial oxidative metabolism that was associated with impaired MPC (mitochondrial pyruvate carrier)−mediated pyruvate utilisation and redirection of glycolytic intermediates into the hexose monophosphate shunt, glycogenesis, and serine biosynthetic pathway. Defects in fatty acid (FA), pyruvate, branched-chain amino acid (BCAA), and ketone body (KB) oxidation, alongside prominent elevation of lactate, represented major features of altered cardiac metabolism in end-stage HF. Chronic accumulation of BCAAs next to suppressed KB and disrupted glucose oxidation were also found in patients with advanced HF, underlying the clinical relevance of the observed alterations. This study provides the comprehensive pattern of metabolic evolution of HF, highlighting several possible avenues to rescue from the HF-prone phenotype, such as promoting BCAA and KB catabolism, or normalising glucose utilisation by overexpressing MPC.