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Genome-wide maps of H3K9me3 and H3K4me3 state in failing heart with or without chaetocin in animal model

ABSTRACT: Epigenetic status has been linked to cardiac hypertrophy and heart failure. Histone deacetylase inhibitors are promising drugs for preventing cardiac remodeling. We previously demonstrated very different patterns of histone H3 lysine 9 trimethylation (H3K9me3) and histone H3 lysine 4 trimethylation (H3K4me3) in failing hearts compared to control hearts in both animal models and clinical heart specimens. Here, we focused on a heart failure-specific histone modification, H3K9me3, and investigated the prognostic efficacy of administering a histone H3K9 methyltransferase inhibitor, chaetocin, to Dahl salt-sensitive rats, an animal model of heart failure. Chaetocin delayed the timing of transition from cardiac hypertrophy to heart failure, and prolonged survival in this animal model. Mitochondrial dysfunction was improved with inhibitor use in the failing heart. ChIP-seq analysis demonstrated that heart failure caused an increase in H3K9me3 alignments in thousands of repetitive elements, including regions neighboring mitochondrial genes, and a corresponding reduction of this effect with inhibitor use. However, at 35 loci, heart failure was conversely associated with a reduction in H3K9me3 alignments, and inhibitor use reversed this effect. These data suggest that excessive heterochromatinization of repetitive elements in the failing heart might impair pumping function with mitochondrial gene silencing. H3K9 methyltransferase inhibitors may be a promising novel therapy for chronic heart failure.

ORGANISM(S): Rattus norvegicus

PROVIDER: GSE69194 | GEO | 2015/05/31

SECONDARY ACCESSION(S): PRJNA284798

REPOSITORIES: GEO

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Project description:Background: Heart failure involves metabolic alterations including increased glycolysis despite unchanged or decreased glucose oxidation. The mitochondrial pyruvate carrier (MPC) regulates pyruvate entry into the mitochondrial matrix, and cardiac deletion of the MPC in mice causes heart failure. How MPC deletion results in heart failure is unknown. Methods: We performed targeted metabolomics and isotope tracing in wildtype (fl/fl) and cardiac-specific Mpc2-/- (CS-Mpc2-/-) hearts after in vivo injection of 13C-glucose. Cardiac glycogen was measured biochemically and by transmission electron microscopy. Cardiac glucose uptake of 2-deoxyglucose was measured and western blotting performed to analyze insulin signaling and enzymatic regulators of glycogen synthesis and degradation. Isotope tracing and glycogen analysis was also performed in hearts from mice fed either low-fat diet or a ketogenic diet previously shown to reverse the heart failure in CS-Mpc2-/- mice. Cardiac glycogen was also assessed in mice infused with angiotensin-II that were fed either low-fat or ketogenic diet. Results: Failing CS-Mpc2-/- hearts contained normal levels of ATP and phosphocreatine, suggesting their heart failure is not caused by energetic stress. These hearts displayed increased enrichment from 13C-glucose and increased glycolytic metabolite pool sizes. 13C enrichment and pool size was also increased for the glycogen intermediate UDP-glucose, as well as increased enrichment of the glycogen pool. Glycogen levels were increased ~6-fold in the failing CS-Mpc2-/- hearts, and glycogen granules were easily detected by electron microscopy. This increased glycogen synthesis occurred despite enhanced inhibitory phosphorylation of glycogen synthase and reduced expression of the priming enzyme glycogenin-1. In young, non-failing CS-Mpc2-/- hearts, increased glycolytic 13C enrichment occurred, but glycogen levels remained low and unchanged compared to fl/fl hearts. Feeding a ketogenic diet to CS-Mpc2-/- mice reversed the heart failure and normalized the cardiac glycogen and glycolytic metabolite accumulation. Cardiac glycogen levels were also elevated in mice infused with angiotensin II, and both the cardiac hypertrophy and glycogen levels were improved by ketogenic diet. Conclusions: Our results indicate that loss of MPC in the heart increases glycolytic metabolism and ultimately glycogen accumulation and heart failure, while a ketogenic diet can reverse both the glycogen accumulation and heart failure. We conclude that maintaining mitochondrial pyruvate import and metabolism is critical for the heart, unless cardiac pyruvate metabolism is dramatically reduced by consumption of a ketogenic diet.

Project description:To identify a novel target for the treatment of heart failure, we examined gene expression in the failing heart. Among the genes analyzed, 12/15 lipoxygenase (12/15-LOX) was markedly up-regulated in heart failure. To determine whether increased expression of 12/15-LOX causes heart failure, we established transgenic mice that overexpressed 12/15-LOX in cardiomyocytes. Echocardiography showed that 12/15-LOX transgenic mice developed systolic dysfunction. Cardiac fibrosis increased in 12/15-LOX transgenic mice with advancing age, and was associated with the infiltration of macrophages. Consistent with these observations, cardiac expression of monocyte chemoattractant protein-1 (Mcp-1) was up-regulated in 12/15-LOX transgenic mice compared with wild-type mice. Treatment with 12-hydroxy-eicosatetraenotic acid, a major metabolite of 12/15-LOX, increased MCP-1 expression in cardiac fibroblasts and endothelial cells, but not in cardiomyocytes. Inhibition of Mcp-1 reduced the infiltration of macrophages into the myocardium and prevented both systolic dysfunction and cardiac fibrosis in 12/15-LOX transgenic mice. Likewise, disruption of 12/15-LOX significantly reduced cardiac Mcp-1 expression and macrophage infiltration, thereby improving systolic dysfunction induced by chronic pressure overload. Our results suggest that cardiac 12/15-LOX is involved in the development of heart failure and that inhibition of 12/15-LOX could be a novel treatment for this condition. Heart failure is still one of the leading causes of death worldwide. Therefore, it is important to elucidate the underlying mechanisms of heart failure and develop more effective treatments for this condition. To clarify the molecular mechanisms of heart failure, we performed microarray analysis using cardiac tissue samples obtained from a hypertensive heart failure model (Dahl salt-sensitive rats). ~300 genes showed significant changes of expression in the failing hearts compared with control hearts. Among the genes analyzed, 12/15-lipoxygenase (12/15-LOX) was most markedly up-regulated in failing hearts compared with control hearts .

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Genome-wide maps of H3K9me3 and H3K4me3 state in failing heart with or without chaetocin in animal model

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