Abstract
Peroxisome proliferator-activated receptor α (PPARα), a ligand-activated nuclear receptor critical for systemic lipid homeostasis, has been shown closely related to cardiac remodeling. However, the roles of cardiomyocyte PPARα in pressure overload-induced cardiac remodeling remains unclear because of lacking a cardiomyocyte-specific Ppara-deficient (PparaΔCM) mouse model. This study aimed to determine the specific role of cardiomyocyte PPARα in transverse aortic constriction (TAC)-induced cardiac remodeling using an inducible PparaΔCM mouse model. PparaΔCM and Pparafl/fl mice were randomly subjected to sham or TAC for 2 weeks. Cardiomyocyte PPARα deficiency accelerated TAC-induced cardiac hypertrophy and fibrosis. Transcriptome analysis showed that genes related to fatty acid metabolism were dramatically downregulated, but genes critical for glycolysis were markedly upregulated in PparaΔCM hearts. Moreover, the hypertrophy-related genes, including genes involved in extracellular matrix (ECM) remodeling, cell adhesion, and cell migration, were upregulated in hypertrophic PparaΔCM hearts. Western blot analyses demonstrated an increased HIF1α protein level in hypertrophic PparaΔCM hearts. PET/CT analyses showed an enhanced glucose uptake in hypertrophic PparaΔCM hearts. Bioenergetic analyses further revealed that both basal and maximal oxygen consumption rates and ATP production were significantly increased in hypertrophic Pparafl/fl hearts; however, these increases were markedly blunted in PparaΔCM hearts. In contrast, hypertrophic PparaΔCM hearts exhibited enhanced extracellular acidification rate (ECAR) capacity, as reflected by increased basal ECAR and glycolysis but decreased glycolytic reserve. These results suggest that cardiomyocyte PPARα is crucial for the homeostasis of both energy metabolism and ECM during TAC-induced cardiac remodeling, thus providing new insights into potential therapeutics of cardiac remodeling-related diseases.