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Aims Heart failure with reduced ejection fraction (HFrEF) is a leading cause of mortality worldwide, requiring novel therapeutic and lifestyle interventions. Metabolic alterations and energy production deficit are hallmarks and thereby promising therapeutic targets for this complex clinical syndrome. We aim to study the molecular mechanisms and effects on cardiac function in rodents with HFrEF of a designer diet in which free essential amino acids—in specifically designed percentages—substituted for protein. Methods and results Wild-type mice were subjected to transverse aortic constriction (TAC) to induce left ventricle (LV) pressure overload or sham surgery. Whole-body glucose homeostasis was studied with glucose tolerance test, while myocardial dysfunction and fibrosis were measured with echocardiogram and histological analysis. Mitochondrial bioenergetics and morphology were investigated with oxygen consumption rate measurement and electron microscopy evaluation. Circulating and cardiac non-targeted metabolite profiles were analyzed by ultrahigh performance liquid chromatography-tandem mass spectroscopy, while RNA-sequencing was used to identify signalling pathways mainly affected. The amino acid-substituted diet shows remarkable preventive and therapeutic effects. This dietary approach corrects the whole-body glucose metabolism and restores the unbalanced metabolic substrate usage—by improving mitochondrial fuel oxidation—in the failing heart. In particular, biochemical, molecular, and genetic approaches suggest that renormalization of branched-chain amino acid oxidation in cardiac tissue, which is suppressed in HFrEF, plays a relevant role. Beyond the changes of systemic metabolism, cell-autonomous processes may explain at least in part the diet’s cardioprotective impact. Conclusion Collectively, these results suggest that manipulation of dietary amino acids, and especially essential amino acids, is a potential adjuvant therapeutic strategy to treat systolic dysfunction and HFrEF in humans.

Heart failure (HF) is accompanied by cardiac hypertrophy (CH) and myocardial tissue remodeling. Epigenetic mechanisms regulate cardiomyocyte (CM) gene expression during CH: the DNA methylation profile and several histone modification marks are profoundly modulated in mouse models of HF and in the human disease. UHRF1 is an epigenetic cofactor connecting DNA methylation to histone methylation. By screening for epigenetic genes upregulated during the early phase of HF, Uhrf1 emerged as a “hit”. We found that UHRF1 is highly expressed in the endothelial cell (EC) compartment under basal conditions in comparison to other myocardial cellular components, and its expression surges in the acute phase of CH induced through transverse aortic constriction (TAC). In vitro studies on HUVECs and H5V cells revealed that silencing of Uhrf1 is associated with defects in cell cycle progression, migration and tube formation. To gain further insight on the role of UHRF1, we generated an EC-specific conditional knockout (cKO) mouse line, Cdh5-CreERT2; Uhrf 1 fl/fl . Compared to control, Uhrf1 -cKO mice subjected to TAC exhibit a worsening of cardiac function associated with increased left ventricular dimension, suggesting a more rapid transition toward HF. Transcriptomic analysis of ECs revealed a robust correlation between UHRF1 depletion and alteration of cell cycle and angiogenesis, in agreement with in vitro results. These results were further corroborated in vivo through EdU injection, matrigel plug and retinal angiogenesis assays, and provided robust evidence for a key role for UHRF1 in the EC response to stress, linking the latter to neo-angiogenesis. We then defined whether the crosstalk between CMs and ECs during stress was altered by the absence of UHRF1. We found that, among other angiocrines, neuregulin-1 (Nrg-1) was strongly downregulated in ECs of Uhrf1 fl/fl mice subjected to TAC. In line with this evidence, ErbB2 and ERK pathways were significantly downregulated in the left ventricle of Uhrf1 fl/fl TAC mice, leading to increased tissue apoptosis.Our study identifies UHRF1 as a critical epigenetic regulator of stress-induced angiogenesis and, more broadly, underlines the relevance of epigenetics in modulating EC gene expression during myocardial stress.